CRRI, Orissa, India develops soft rice
A rice variety sourced from Assam may soon change the cooking pattern of rice in the country. Termed as soft rice or komal chawl, this rice has low starch content. It does not need boiling, and becomes eatable after being soaked in water for less than an hour.
Scientists have studied the rice named Aghonibora and has found that it retains quality. “It takes 140-145 days to mature; measured 90 cm in height and per hectare yield is about 4.5 tonne in preliminary testing. According to the CRRI, a number of rice varieties of Assamese origin--Aghonibora, Bhogalibora, Chakua and Misiri--classified as ‘soft’ rices or komal chawl, are low in amylose (a kind of starch) content. Grains of these varieties do not require cooking in boiled water, as they become fit to eat just after being soaked in normal water for less than an hour (One has only to soak the rice in warm water for 15 minutes and in cold water for around 40 minutes) to render it fit for consumption.
The CRRI has also introduced a flood-resistant paddy variety, Swarna Sub1, with a gene sourced from Philippines-based International Rice Research Institute (IRRI). Swarna Sub1 can withstand floodwater for close to two weeks.
Thursday, October 1, 2009
Classification of Fungicides
FUNGICIDES
Definitions –
1.Fungicide - is a chemical, which is capable of killing fungi.
2. Antibiotic- is a chemical produced by a microorganism, which is inhibitory to other organisms. Fungicides can be classified as protectants, eradicants & systemic fungicides.
a. Protectant- Fungicide which is effective only if applied prior to fungal infection is called Protectant. Example – Mancozeb, Zineb.
b. Eradicant – is the one, which removes fungi from an infection court. An Eradicant can penetrate the host tissues to a limited extent & eliminate an established infection. Example – Lime Sulpher.
c. Systemic Fungicides- Systemic fungicides are the compounds, which are transported over a considerable distance in plant system after-penetration. They kill fungi, which are found remote from the point of application.
I) SULPHER FUNGICIDES
a) Inorganic Sulpher fungicides - includes elemental Sulpher, wettable Sulpher & lime Sulpher. Sulpher fungicides effectively control powdery mildew of different crops such as chilli, okra, grape, rubber, mango, citrus, black gram & green gram. Sulpher controls tikka leaf spot of groundnut & Diplocapron black spot of rose. Sulpher dust is used as seed treatment also.
b) Organic Sulpher fungicides- Dithiocarba mates are the organic Sulpher fungicides. They are divided into-
(i) Dialkyldithiocarbamtes- Thiram, Ziram & ferban & Ziram is used as Protectant & sprayed before the outbreak of the disease. It controls early blight of potato & tomato and anthracnose disease of cucurbits & beans. Thiram is commonly used for seed treatment. Thiram seed treatment controls seed-borne pathogens as well as soil born pathogens. It controls seed borne infection of colletotrichum capsici of chilli, root rot of groundnut, sorghum grain smut & Helminthosporium leaf spot of rice. As seed treatment it controls soil-borne infection of Phthium spp. of tomato, tobacco & brinjal (Damping off) Rhizoctonia solani of cotton & Sheath blight of rice. Ferban control diseases of apple. It controls leaf spot of banana, leaf mould of tomato & leaf spot of coffee.
(ii) Monoalkyldithio carbamates- maneb, Zineb, Mancozeb, vapam & nabam. Zineb controls anthracnose disease of bean, chilli, & cucurbits, rust disease of wheat, sorghum & bajra, downy mildew of grapevine, cucurbits, Onion & cabbage, cercospora leaf spot of groundnut, cabbage, cauliflower, Alternaria leaf spot of potato, tomato singer. Mancozeb is widely used for the control of late blight of potato, cercospora leaf spot of groundnut, cucurbits & sugar beet. Helminthosporium leaf spot of rice, ragi, maize & sorghum, downy mildew of grapevine & tobacco, rust disease of wheat groundnut, bajra & sorghum, Alternaria leaf spot of ginger, potato, tomato & wheat anthracnose of chilli, grapevine, sorghum, bean & cucurbits.
Vapam controls cotton wilt & damping off of papaya, tobacco & tomato. It controls nematodes also.
(II) Copper Fungicides
(a) Copper Sulphate Preparations – It include Bordeaux mixture, Bordeaux Paste, Burgundy mixture, & chestnut compound. Bordeaux mixture is highly effective against late blight of potato, downy mildew of grapevine, coffee rust, betel vine wilt, pepper wilt, tomato early & late blights & coconut will & bud rot.
(b) Copper Carbonate Preparations- It controls many fungal diseases of apple, pear, peach, plums & apricot.
c) Copper Oxychloride Preparations – Some formulations available in the market are Fytolan, Blue copper, Blitox etc. They are generally effective against all diseases against which Bordeaux mixture has been found effective.
Mercury Fungicides-
Various mercury fungicides sold in the market are ceresan, aretan, agallol, wet ceresan, Dry ceresan etc. They are effective as seed treatment.
IV Heterocylic nitrogen compounds-
a) Captan- It is commercially marketed as Captan, orthocide, vancide etc. It is Protectant fungicide. It controls maize helminthosporiose, chilli fruit rot & apple scab. It is mostly used as seed treatment.
b) Folpet – It is commercially marketed as Phaltan. It controls rose black spot & apple scab.
(c) Captofol – It is marketed as Difolotan, Foltaf etc.
It effectively controls sheath rot of rice & mango anthracnose.
V) Quinone Fungicides-
a) Chloranil – It is commercially marketed as spergon. It is good seed dressing fungicide. It controls grain smut of sorghum & damping off of beans & cotton.
b) Dichlone- The commercial name of the fungicide is phygon. It controls peach leaf curl, apple scab & bean anthracnose.
Miscellaneous Fungicides-
a) Quintozene - Commercial names of the fungicide are Brassicol, Terraclor, PCNB & Tritisan. It is used to control soil borne pathogens. It is effective against Rhizoctonia Solani, Macrophomina Phaseolina & Sclerotiana Sclerotiorum.
b) Dinocap - It is marketed in the name of karthane, Arathane, Mildex etc. Dinocap is effective in controlling powdery mildews.
c) Fenaminsosulph- it is commercially known as Dexon. It is highly effective against phycomycetes like pythium phytophthora & Aphanomyces.
d) Dicloran_ Its trade name is Botran. It controls Botrytis infection in several crops.
e) Chlorothalonil- It is marketed as Daconil & Kavach. It controls both tikka leaf spot & rust disease of groundnut & betelvine wilt.
SYSTEMIC FUNGICIDES-
Some of the systemic fungicides are-
a) Carbendazim – It is marketed as Bavistin, Derosal, B-Sten etc. It controls Powdery Mildews, smut diseases & bunts.
b) Benomyl- Benomyl is effective against Fusarium , Rhizoctonia, Macrophomina, Cercospora, Colletotrichum, Puricularia, Verticillium, Phomopsis, Septoria, Erysiphe, Plasmodiophora, Botrytis, Ustilago, Urocystis & Tilletia Spp.
c) Thiabendazole – It is commercially available as Tecto & Mertect. It controls wheat bunt.
d) Carboxin- it is commercially available as vitavax. It is the most effective fungicide to control internally seed borne loose smuts of cereals.
e) Oxycarboxin- it is commercially marketed as Plantvax. It is specifically effective against rust pathogens.
f) Pyracarbolid- it is commercially available as sicarol. It is effective against rust & smut & Rhizoctonia Spp.
g) Metalaxyl- it is marketed as Ridomil & Apron. Metalaxyl is highly effective against phycomyces fungi like Phytophthrora, Pythium, Scierospora, Pseudopernospora, Plasmopara, Sclerophthora & Albugo.
h) Tride morph- its trade name is calixin. It is mainly used against powdery mildews as foliar sprays
i) Pyroquilon- it is commercially available as Fongorene. It effectively controls rice blast.
j) Kitazin- it is commercially marketed as Kitazin. It is highly effective against rice blast.
k) Tricyclazole – it is commercially marketed as Beam. It is highly specific for the control of rice blast.
l) Probenazole- its commercial name is oryzemate. It is also specific against rice blast.
m) Triadimefon- it is commercially market as Bayleton. It is highly effective against powdery mildews. It also controls rust diseases.
n) Biloxazole- it is marketed as Baycor. It is effective against cercospora diseases & rusts.
o) Triademenol- The commercial name of the fungicide is Bayton. As seed treatment it controls smut & powdery mildews.
Definitions –
1.Fungicide - is a chemical, which is capable of killing fungi.
2. Antibiotic- is a chemical produced by a microorganism, which is inhibitory to other organisms. Fungicides can be classified as protectants, eradicants & systemic fungicides.
a. Protectant- Fungicide which is effective only if applied prior to fungal infection is called Protectant. Example – Mancozeb, Zineb.
b. Eradicant – is the one, which removes fungi from an infection court. An Eradicant can penetrate the host tissues to a limited extent & eliminate an established infection. Example – Lime Sulpher.
c. Systemic Fungicides- Systemic fungicides are the compounds, which are transported over a considerable distance in plant system after-penetration. They kill fungi, which are found remote from the point of application.
I) SULPHER FUNGICIDES
a) Inorganic Sulpher fungicides - includes elemental Sulpher, wettable Sulpher & lime Sulpher. Sulpher fungicides effectively control powdery mildew of different crops such as chilli, okra, grape, rubber, mango, citrus, black gram & green gram. Sulpher controls tikka leaf spot of groundnut & Diplocapron black spot of rose. Sulpher dust is used as seed treatment also.
b) Organic Sulpher fungicides- Dithiocarba mates are the organic Sulpher fungicides. They are divided into-
(i) Dialkyldithiocarbamtes- Thiram, Ziram & ferban & Ziram is used as Protectant & sprayed before the outbreak of the disease. It controls early blight of potato & tomato and anthracnose disease of cucurbits & beans. Thiram is commonly used for seed treatment. Thiram seed treatment controls seed-borne pathogens as well as soil born pathogens. It controls seed borne infection of colletotrichum capsici of chilli, root rot of groundnut, sorghum grain smut & Helminthosporium leaf spot of rice. As seed treatment it controls soil-borne infection of Phthium spp. of tomato, tobacco & brinjal (Damping off) Rhizoctonia solani of cotton & Sheath blight of rice. Ferban control diseases of apple. It controls leaf spot of banana, leaf mould of tomato & leaf spot of coffee.
(ii) Monoalkyldithio carbamates- maneb, Zineb, Mancozeb, vapam & nabam. Zineb controls anthracnose disease of bean, chilli, & cucurbits, rust disease of wheat, sorghum & bajra, downy mildew of grapevine, cucurbits, Onion & cabbage, cercospora leaf spot of groundnut, cabbage, cauliflower, Alternaria leaf spot of potato, tomato singer. Mancozeb is widely used for the control of late blight of potato, cercospora leaf spot of groundnut, cucurbits & sugar beet. Helminthosporium leaf spot of rice, ragi, maize & sorghum, downy mildew of grapevine & tobacco, rust disease of wheat groundnut, bajra & sorghum, Alternaria leaf spot of ginger, potato, tomato & wheat anthracnose of chilli, grapevine, sorghum, bean & cucurbits.
Vapam controls cotton wilt & damping off of papaya, tobacco & tomato. It controls nematodes also.
(II) Copper Fungicides
(a) Copper Sulphate Preparations – It include Bordeaux mixture, Bordeaux Paste, Burgundy mixture, & chestnut compound. Bordeaux mixture is highly effective against late blight of potato, downy mildew of grapevine, coffee rust, betel vine wilt, pepper wilt, tomato early & late blights & coconut will & bud rot.
(b) Copper Carbonate Preparations- It controls many fungal diseases of apple, pear, peach, plums & apricot.
c) Copper Oxychloride Preparations – Some formulations available in the market are Fytolan, Blue copper, Blitox etc. They are generally effective against all diseases against which Bordeaux mixture has been found effective.
Mercury Fungicides-
Various mercury fungicides sold in the market are ceresan, aretan, agallol, wet ceresan, Dry ceresan etc. They are effective as seed treatment.
IV Heterocylic nitrogen compounds-
a) Captan- It is commercially marketed as Captan, orthocide, vancide etc. It is Protectant fungicide. It controls maize helminthosporiose, chilli fruit rot & apple scab. It is mostly used as seed treatment.
b) Folpet – It is commercially marketed as Phaltan. It controls rose black spot & apple scab.
(c) Captofol – It is marketed as Difolotan, Foltaf etc.
It effectively controls sheath rot of rice & mango anthracnose.
V) Quinone Fungicides-
a) Chloranil – It is commercially marketed as spergon. It is good seed dressing fungicide. It controls grain smut of sorghum & damping off of beans & cotton.
b) Dichlone- The commercial name of the fungicide is phygon. It controls peach leaf curl, apple scab & bean anthracnose.
Miscellaneous Fungicides-
a) Quintozene - Commercial names of the fungicide are Brassicol, Terraclor, PCNB & Tritisan. It is used to control soil borne pathogens. It is effective against Rhizoctonia Solani, Macrophomina Phaseolina & Sclerotiana Sclerotiorum.
b) Dinocap - It is marketed in the name of karthane, Arathane, Mildex etc. Dinocap is effective in controlling powdery mildews.
c) Fenaminsosulph- it is commercially known as Dexon. It is highly effective against phycomycetes like pythium phytophthora & Aphanomyces.
d) Dicloran_ Its trade name is Botran. It controls Botrytis infection in several crops.
e) Chlorothalonil- It is marketed as Daconil & Kavach. It controls both tikka leaf spot & rust disease of groundnut & betelvine wilt.
SYSTEMIC FUNGICIDES-
Some of the systemic fungicides are-
a) Carbendazim – It is marketed as Bavistin, Derosal, B-Sten etc. It controls Powdery Mildews, smut diseases & bunts.
b) Benomyl- Benomyl is effective against Fusarium , Rhizoctonia, Macrophomina, Cercospora, Colletotrichum, Puricularia, Verticillium, Phomopsis, Septoria, Erysiphe, Plasmodiophora, Botrytis, Ustilago, Urocystis & Tilletia Spp.
c) Thiabendazole – It is commercially available as Tecto & Mertect. It controls wheat bunt.
d) Carboxin- it is commercially available as vitavax. It is the most effective fungicide to control internally seed borne loose smuts of cereals.
e) Oxycarboxin- it is commercially marketed as Plantvax. It is specifically effective against rust pathogens.
f) Pyracarbolid- it is commercially available as sicarol. It is effective against rust & smut & Rhizoctonia Spp.
g) Metalaxyl- it is marketed as Ridomil & Apron. Metalaxyl is highly effective against phycomyces fungi like Phytophthrora, Pythium, Scierospora, Pseudopernospora, Plasmopara, Sclerophthora & Albugo.
h) Tride morph- its trade name is calixin. It is mainly used against powdery mildews as foliar sprays
i) Pyroquilon- it is commercially available as Fongorene. It effectively controls rice blast.
j) Kitazin- it is commercially marketed as Kitazin. It is highly effective against rice blast.
k) Tricyclazole – it is commercially marketed as Beam. It is highly specific for the control of rice blast.
l) Probenazole- its commercial name is oryzemate. It is also specific against rice blast.
m) Triadimefon- it is commercially market as Bayleton. It is highly effective against powdery mildews. It also controls rust diseases.
n) Biloxazole- it is marketed as Baycor. It is effective against cercospora diseases & rusts.
o) Triademenol- The commercial name of the fungicide is Bayton. As seed treatment it controls smut & powdery mildews.
Wednesday, August 19, 2009
MASS COMMUNICATION AND METHODS OF MASS COMMUNICATION’S
Importance:
Mass media enable extension workers to greatly increase their teaching efficiency. Publications, news papers articles, circular letters, radio, television, exhibits, posters etc., provide helpful repetition for those contacted personally or through groups. They also facilitate dissemination of information to a much larger & different clientele. Even though the intensity of the teaching contact, through mass media is less, the large number of people reached and the low cost per unit of coverage more than off-set the lack of intensity. The extension teaching plan which neglects the communication possibility through mass media fails to fully capitalize on what has already been invested in the more intensive contact methods.
Definitions of Communication
Leagans says, “It is a process by which two or more people exchange ideas, facts, feelings or impressions in a way that each gains a common understanding of message. In essence it is the act of getting a sender and a receiver tuned together for a particular message or series of messages.”
Communication is the imparting or interchange of thoughts, opinions or information by speech, writing or science. (American College Dictionary)
According to Rogers & Shoemaker (1970) Communication is the process by which messages are transferred from a source to receiver.
Van de Ban & Hawkins (1988) defined Communication as the process of sending & receiving messages through channels which establishes common meanings between a source and a receiver.
Communication is the process by which the message is transmitted from the source to the receiver (Rogers, 1983)
Communication is a mutual interchange of ideas by any effective means (Thayer 1968)
Communication is anything that conveys meaning that carries a message from one person to another (Brooker 1949)
Communication Methods
A method is a procedure or process for attaining an objective. The choice of channels or method of communication, also known as extension teaching method, generally depends on the number and location of the target audience, and the time available for communication.
Selection of effective combination of extension method
A combination of extension teaching methods or that of mass media and inter personal sources is perhaps the most effective way of reaching people with new ideas and persuading them to utilize these innovations.
The basic idea behind this is:
The more the senses of the learner are involved in the learning process, the greater the learning.
To ensure action on the part of learner, several exposures may be necessary in order to motivate, remind and persuade them.
It will depend on the situation as well as knowledge and experience of the extension agent.
Basically Communication Methods Are Classified As:-
1. Interpersonal Communication
2. Mass media Communication
Interpersonal Communication
It consists of a face to face exchange between two or more individuals. The message flow is from one to a few individuals. Feed back is immediate and usually plentiful, and the messages are often relatively high in socio-emotional content
Mass media Communication
It involves some type of hardware equipment that enables a source of one or a few individuals to reach a large audience. Feedback is limited and delayed and the messages are often relatively low in socio-emotional content.
[A]. Interpersonal Methods
In this method, the extension agent communicates with the people individually, maintaining separate identity of each person. This method is followed when the number of people to be contacted are few, are conveniently located close to the communicator and sufficient time is available for communication. eg. Farm & Home visit, Farmers call etc
Advantages
1. Helps in selecting demonstrators & local leaders
2. Helps in changing attitudes of people
3. Helps in teaching complex practices.
4. Facilitates transfer of technology
5. Getting feedback information
Limitations
1. This method is time consuming & relatively expensive
2. Has low coverage of audience
3. Extension agent may develop favoritism or bias towards some persons
[B]. Group Methods
It may be defined as an aggregate of small number of people in reciprocal communication and interaction around some common interest. In this method extension agent communicates with the people in groups and not as individual persons. eg. Result demonstration, Method demonstration, group meeting etc.
Objectives
1. It helps for selection of village leaders.
2. It gives the idea for the need of people.
3. Less expensive than individual method due to more coverage
4. More effective than mass method in stimulating action.
Limitations
1. Wide diversity of interest of people may create a difficulty to learning situation
2. Every body wants for their individual development.
[C].Mass Methods
In this method, extension agent communicates with vast & heterogeneous mass of peoples, without taking into consideration their individual identity. This method is followed where a large & widely dispersed audience is to be communicated within a short period of time. The size of audience may be a few hundred in mass meeting, few thousands in campaign & exhibition and millions in newspaper, radio & TV.
Advantage:
1. Suitable for creating general awareness amongst the people.
2. Helps in transferring knowledge, forming & changing opinion.
3. Large number of people can be communicated within short time
Limitations:-
1. Less intensive method.
2. Cannot be held frequently
3. Little scope for personal contact with the audience.
4. Little control over the responses of audience.
5. Difficult in getting feedback information & evaluation of results
Means of Mass Communication:
Newspaper:
Newspaper is a bunch of loose printed papers properly folded, which contains news, views, advertisements etc and is offered for sale at regular intervals, particularly daily or weekly. Newspapers are usually printed on a special type of paper known as newsprint.
Daily newspapers are resource strong and are published from national/ state capitals or big cities. Their approach is cosmopolite and the circulation may range from about a lack to several lakhs. Some of the daily newspaper are quite big and are published simultaneously from several cities.
Selection of matter for writing in news paper
Prepare a draft write up on the topic in simple language, furnishing current and important information. The lead i.e. the opening sentence or paragraph is important and should be comprehensive. Give a suitable caption
1. The draft should contain information on what, who, when, where and why.
2. Revise the draft and produce a brief, lucid, interesting and informative write up.
3. In required, enclose photographs on glossy paper with the write up.
Advantages:
1- Large circulation.
2- Cheaper than any other mass communication device.
Limitations:
1. Only literate people generally can take advantage of this medium.
2. Increase in the price of newspapers may restrict their circulation.
Television
Television is an electronic audio-visual medium which provides pictures with synchronized sound. This medium is cosmopolite in approach and can be used to create instant mass awareness. Television combines the immediacy of radio with the mobility of Cinema and can carry messages over long distance at a relatively low unit cost.
Television is multi media equipment as it can include motion picture, recording, slide, photograph, drawing, poster etc. Television can show recorded as well as live programmes.
Both recording and playback equipments are transportable, allowing flexibility of use
Purpose:
1. People learn through the eye, & will remember things better if they see them.
2. The message on the tv screen are presented in the simplest manner possible.
Advantages
1. To create a general awareness amongst the people about agricultural and rural development.
2. To provide need based programmes to the rural audience.
3. To show the rural people in general & the farmer in particular what to do,how to do,& when to do.
Limitations
1. Requires lots of planning, preparation, trained personal and availability of equipments.
2. Audience participation depends on costly receiving sets and availability of electricity.
3. TV is an electronic audio visual medium,which provides pictures with synchronize sound.
4. Seldom goes beyond creating general awareness of audience
Video Films:
Video films are really a series of still pictures on a long strip of film. Each picture is flashed momentarily on the screen and the rapid succession of still pictures-(each of which shows the subject in a slightly different position) – gives an illusion of movements. Usually 70 mm and 35 mm. films are used for commercial entertainment, 16 mm. Film for educational movies, and 8 mm. Film for domestic pictures.
Advantages:
1. A complete process involving motion can be shown in a short time.
2. People identify themselves with those in the films.
3. Compel attention.
4. Heighten reality.
5. Speed or slow down time.
6. Bring the distant past and the distant present into learning situation.
7. Enlarge or reduce actual size of objects.
Limitations:
1. Special equipment is necessary.
2. The equipment is costly.
3. Some sort of power is required to operate the projectors.
4. Transportation maintenance & storage of equipment & materials require special consideration & skill.
5. Suitable halls for showing motion picture are not available in many places.
6. Bring the distant past and the distant present into learning situation.
7. Enlarge or reduce actual size of objects.
Purpose:
1. To present facts in an interesting way.
2. To attract audience.
3. To arouse interest.
4. To change attitudes.
5. To bring new practices to village In a short time.
6. To reach illiterate as well as literate people.
Points to remember:
1. Be thoroughly familiar with the subject you plan to teach and how exactly the film supports the ideas you want to get across.
2. Preview the film
3. before showing the film, explain the subject, tell why it is important and stimulate viewers to look for certain thing in the film.
4. At the end of the show, have a forum
5. Follow up (capitalise the enthusiasm generated)
Mass Meeting:
Mass meeting is held to communicate interesting and useful information to a large audience at a time. The size of the audience for mass meeting may be a few hundreds, but at the time of fairs or festivals it may be few thousands
Objectives
1. To focus attention of the people on some important topic.
2. To enlist people’s participation in community work.
3. To appear personally before a large audience
Advantage
1. Reaches many who read little or none at all.
2. A means of informing non farm people (tax payers) about agricultural matters.
3. Reaches people who are unable to attend extension meetings.
4. Builds interest in other extension media.
Limitations
1. In-depth discussion of the topic not possible.
2. Can’t be held frequently.
3. Difficult to get feed back information.
Radio:
Radio is an electronic audio-medium for broadcasting programmes to the audience. This medium is cosmopolite in approach and is suitable for communication to millions of people widely dispersed and situated in remote areas. Radio is suitable for creating general awareness amongst the people, help change their attitude and reinforces learning. It reaches a large number of people at a very low cost.
Purpose:
1. To reach large numbers of people quickly & inexpensively.
2. To reach people not reach by other means.
3. To stimulate participation in extension through all other media.
4. To build enthusiasm & maintain interest.
Advantages:
1. Can reach more quickly than any other means of communication.
2. Specially suited to give emergency & timely information(e.g. weather,pest-out-break etc.)
3. Relatively cheap.
4. Reaches many who read little or none at all.
5. Reaches people who are unable to attend extension meetings.
6. A means of informing non farm people( tax payers) about agricultural matters.
7. Builds interest in other extension media.
8. Possible to do other things while listening.
Limitations:
1. Limited number of broadcasting stations.
2. Not within reach of all farmers.
3. Recommendations may not apply to individual needs.
4. No turning back if not needed.
5. Frequently loses out in competition with entertainment.
6. Difficult to check on results.
PROJECTORS:
The lantern slides is one of the most popular & versatile visual in extension education. It is a transparent picture on glass or film) which is projected by focusing light through it from electric bulb, petromax or lantern.
Reasons for the popularity of lantern slides are:
1. They can be made by the individual worker at low cost.
2. They can be made either in natural colour in black and white.
3. Both the slides and projections equipment are relatively light and can be easily transported.
4. Slide sequence can be readily changed to keep them timely and localized.
5. We can use the full set of slides or select only a few slides required for our subject.
6. Each slide can be retained for any length of time according to the teaching situation.
Limitations:
1. They do not show action.
2. They normally require live narration, unless synchronized with tape recorder.
3. They require close co-operation within a projections throughout the presentation if the speaker desires to be in front of his audience.
Mass media enable extension workers to greatly increase their teaching efficiency. Publications, news papers articles, circular letters, radio, television, exhibits, posters etc., provide helpful repetition for those contacted personally or through groups. They also facilitate dissemination of information to a much larger & different clientele. Even though the intensity of the teaching contact, through mass media is less, the large number of people reached and the low cost per unit of coverage more than off-set the lack of intensity. The extension teaching plan which neglects the communication possibility through mass media fails to fully capitalize on what has already been invested in the more intensive contact methods.
Definitions of Communication
Leagans says, “It is a process by which two or more people exchange ideas, facts, feelings or impressions in a way that each gains a common understanding of message. In essence it is the act of getting a sender and a receiver tuned together for a particular message or series of messages.”
Communication is the imparting or interchange of thoughts, opinions or information by speech, writing or science. (American College Dictionary)
According to Rogers & Shoemaker (1970) Communication is the process by which messages are transferred from a source to receiver.
Van de Ban & Hawkins (1988) defined Communication as the process of sending & receiving messages through channels which establishes common meanings between a source and a receiver.
Communication is the process by which the message is transmitted from the source to the receiver (Rogers, 1983)
Communication is a mutual interchange of ideas by any effective means (Thayer 1968)
Communication is anything that conveys meaning that carries a message from one person to another (Brooker 1949)
Communication Methods
A method is a procedure or process for attaining an objective. The choice of channels or method of communication, also known as extension teaching method, generally depends on the number and location of the target audience, and the time available for communication.
Selection of effective combination of extension method
A combination of extension teaching methods or that of mass media and inter personal sources is perhaps the most effective way of reaching people with new ideas and persuading them to utilize these innovations.
The basic idea behind this is:
The more the senses of the learner are involved in the learning process, the greater the learning.
To ensure action on the part of learner, several exposures may be necessary in order to motivate, remind and persuade them.
It will depend on the situation as well as knowledge and experience of the extension agent.
Basically Communication Methods Are Classified As:-
1. Interpersonal Communication
2. Mass media Communication
Interpersonal Communication
It consists of a face to face exchange between two or more individuals. The message flow is from one to a few individuals. Feed back is immediate and usually plentiful, and the messages are often relatively high in socio-emotional content
Mass media Communication
It involves some type of hardware equipment that enables a source of one or a few individuals to reach a large audience. Feedback is limited and delayed and the messages are often relatively low in socio-emotional content.
[A]. Interpersonal Methods
In this method, the extension agent communicates with the people individually, maintaining separate identity of each person. This method is followed when the number of people to be contacted are few, are conveniently located close to the communicator and sufficient time is available for communication. eg. Farm & Home visit, Farmers call etc
Advantages
1. Helps in selecting demonstrators & local leaders
2. Helps in changing attitudes of people
3. Helps in teaching complex practices.
4. Facilitates transfer of technology
5. Getting feedback information
Limitations
1. This method is time consuming & relatively expensive
2. Has low coverage of audience
3. Extension agent may develop favoritism or bias towards some persons
[B]. Group Methods
It may be defined as an aggregate of small number of people in reciprocal communication and interaction around some common interest. In this method extension agent communicates with the people in groups and not as individual persons. eg. Result demonstration, Method demonstration, group meeting etc.
Objectives
1. It helps for selection of village leaders.
2. It gives the idea for the need of people.
3. Less expensive than individual method due to more coverage
4. More effective than mass method in stimulating action.
Limitations
1. Wide diversity of interest of people may create a difficulty to learning situation
2. Every body wants for their individual development.
[C].Mass Methods
In this method, extension agent communicates with vast & heterogeneous mass of peoples, without taking into consideration their individual identity. This method is followed where a large & widely dispersed audience is to be communicated within a short period of time. The size of audience may be a few hundred in mass meeting, few thousands in campaign & exhibition and millions in newspaper, radio & TV.
Advantage:
1. Suitable for creating general awareness amongst the people.
2. Helps in transferring knowledge, forming & changing opinion.
3. Large number of people can be communicated within short time
Limitations:-
1. Less intensive method.
2. Cannot be held frequently
3. Little scope for personal contact with the audience.
4. Little control over the responses of audience.
5. Difficult in getting feedback information & evaluation of results
Means of Mass Communication:
Newspaper:
Newspaper is a bunch of loose printed papers properly folded, which contains news, views, advertisements etc and is offered for sale at regular intervals, particularly daily or weekly. Newspapers are usually printed on a special type of paper known as newsprint.
Daily newspapers are resource strong and are published from national/ state capitals or big cities. Their approach is cosmopolite and the circulation may range from about a lack to several lakhs. Some of the daily newspaper are quite big and are published simultaneously from several cities.
Selection of matter for writing in news paper
Prepare a draft write up on the topic in simple language, furnishing current and important information. The lead i.e. the opening sentence or paragraph is important and should be comprehensive. Give a suitable caption
1. The draft should contain information on what, who, when, where and why.
2. Revise the draft and produce a brief, lucid, interesting and informative write up.
3. In required, enclose photographs on glossy paper with the write up.
Advantages:
1- Large circulation.
2- Cheaper than any other mass communication device.
Limitations:
1. Only literate people generally can take advantage of this medium.
2. Increase in the price of newspapers may restrict their circulation.
Television
Television is an electronic audio-visual medium which provides pictures with synchronized sound. This medium is cosmopolite in approach and can be used to create instant mass awareness. Television combines the immediacy of radio with the mobility of Cinema and can carry messages over long distance at a relatively low unit cost.
Television is multi media equipment as it can include motion picture, recording, slide, photograph, drawing, poster etc. Television can show recorded as well as live programmes.
Both recording and playback equipments are transportable, allowing flexibility of use
Purpose:
1. People learn through the eye, & will remember things better if they see them.
2. The message on the tv screen are presented in the simplest manner possible.
Advantages
1. To create a general awareness amongst the people about agricultural and rural development.
2. To provide need based programmes to the rural audience.
3. To show the rural people in general & the farmer in particular what to do,how to do,& when to do.
Limitations
1. Requires lots of planning, preparation, trained personal and availability of equipments.
2. Audience participation depends on costly receiving sets and availability of electricity.
3. TV is an electronic audio visual medium,which provides pictures with synchronize sound.
4. Seldom goes beyond creating general awareness of audience
Video Films:
Video films are really a series of still pictures on a long strip of film. Each picture is flashed momentarily on the screen and the rapid succession of still pictures-(each of which shows the subject in a slightly different position) – gives an illusion of movements. Usually 70 mm and 35 mm. films are used for commercial entertainment, 16 mm. Film for educational movies, and 8 mm. Film for domestic pictures.
Advantages:
1. A complete process involving motion can be shown in a short time.
2. People identify themselves with those in the films.
3. Compel attention.
4. Heighten reality.
5. Speed or slow down time.
6. Bring the distant past and the distant present into learning situation.
7. Enlarge or reduce actual size of objects.
Limitations:
1. Special equipment is necessary.
2. The equipment is costly.
3. Some sort of power is required to operate the projectors.
4. Transportation maintenance & storage of equipment & materials require special consideration & skill.
5. Suitable halls for showing motion picture are not available in many places.
6. Bring the distant past and the distant present into learning situation.
7. Enlarge or reduce actual size of objects.
Purpose:
1. To present facts in an interesting way.
2. To attract audience.
3. To arouse interest.
4. To change attitudes.
5. To bring new practices to village In a short time.
6. To reach illiterate as well as literate people.
Points to remember:
1. Be thoroughly familiar with the subject you plan to teach and how exactly the film supports the ideas you want to get across.
2. Preview the film
3. before showing the film, explain the subject, tell why it is important and stimulate viewers to look for certain thing in the film.
4. At the end of the show, have a forum
5. Follow up (capitalise the enthusiasm generated)
Mass Meeting:
Mass meeting is held to communicate interesting and useful information to a large audience at a time. The size of the audience for mass meeting may be a few hundreds, but at the time of fairs or festivals it may be few thousands
Objectives
1. To focus attention of the people on some important topic.
2. To enlist people’s participation in community work.
3. To appear personally before a large audience
Advantage
1. Reaches many who read little or none at all.
2. A means of informing non farm people (tax payers) about agricultural matters.
3. Reaches people who are unable to attend extension meetings.
4. Builds interest in other extension media.
Limitations
1. In-depth discussion of the topic not possible.
2. Can’t be held frequently.
3. Difficult to get feed back information.
Radio:
Radio is an electronic audio-medium for broadcasting programmes to the audience. This medium is cosmopolite in approach and is suitable for communication to millions of people widely dispersed and situated in remote areas. Radio is suitable for creating general awareness amongst the people, help change their attitude and reinforces learning. It reaches a large number of people at a very low cost.
Purpose:
1. To reach large numbers of people quickly & inexpensively.
2. To reach people not reach by other means.
3. To stimulate participation in extension through all other media.
4. To build enthusiasm & maintain interest.
Advantages:
1. Can reach more quickly than any other means of communication.
2. Specially suited to give emergency & timely information(e.g. weather,pest-out-break etc.)
3. Relatively cheap.
4. Reaches many who read little or none at all.
5. Reaches people who are unable to attend extension meetings.
6. A means of informing non farm people( tax payers) about agricultural matters.
7. Builds interest in other extension media.
8. Possible to do other things while listening.
Limitations:
1. Limited number of broadcasting stations.
2. Not within reach of all farmers.
3. Recommendations may not apply to individual needs.
4. No turning back if not needed.
5. Frequently loses out in competition with entertainment.
6. Difficult to check on results.
PROJECTORS:
The lantern slides is one of the most popular & versatile visual in extension education. It is a transparent picture on glass or film) which is projected by focusing light through it from electric bulb, petromax or lantern.
Reasons for the popularity of lantern slides are:
1. They can be made by the individual worker at low cost.
2. They can be made either in natural colour in black and white.
3. Both the slides and projections equipment are relatively light and can be easily transported.
4. Slide sequence can be readily changed to keep them timely and localized.
5. We can use the full set of slides or select only a few slides required for our subject.
6. Each slide can be retained for any length of time according to the teaching situation.
Limitations:
1. They do not show action.
2. They normally require live narration, unless synchronized with tape recorder.
3. They require close co-operation within a projections throughout the presentation if the speaker desires to be in front of his audience.
AQUATIC WEEDS AND THEIR CONTROL
INTRODUCTION
Aquatic weed are those unwanted plants which grow in water and complete at least a part of their life cycle in water. Many aquatic plants are desirable since they may play temporarily a beneficial role in reducing agricultural, domestic and industrial pollution. Letting a crop of plants grow in a lake or pond and then killing it over a period of time, and consequently releasing nutrients back into the water, may help in fish production. However, many aquatic plans are considered weeds when they deprive human beings of all facets of efficient use of water and cause harmful effects, some of which are discussed below.
Submersed, immersed, emerged and marginal weeds in and along irrigation canals, ditches, and drainage channels impede water flow, increase evaporation, cause damage to canals and structures, and clog gates, siphons, valves, sprinkler heads bridge piers, pumps, etc.
Floating and deep-rooted submersed weeds interfere with navigation. Some of the tougher and densely growing weeds, e.g. water hyacinth and alligator weed become impenetrable and prevent boats and even steamers moving through. Submersed and floating aquatic weeds in farm ponds, village tanks and water reservoirs reduce their utility for water storage and irrigation.
Aquatic weed growth also prevents or impairs the use of inland waters for fishing. The weed assimilates large quantities of nutrients from water, thus reducing their availability for desirable planktonic algae. They cause oxygen deficiency and prevent gaseous exchange with atmosphere, resulting in an adverse effect on fish production. Excessive growth of these weeds may provide excessive cover, resulting in an overpopulation of small fish and interference with fish harvesting.
Aquatic weeds provide a suitable habitat for development of mosquitoes in impounded waters, causing malaria, filariasis and encephalitis. These weeds serve as the primary vector for the disease-causing organisms.
Aquatic weeds reduce the recreational values of lakes, tanks, streams, etc. as the water is made turbid or dirty with an undesirable odour
TYPES OF AQUATIC WEED
There are two types of aquatic plants: algae and hydrophytes.
ALGAE-Algae normally inhabit the surface of fresh and saline waters exposed to sunlight. While some kinds of algae are found in solid and on terrestrial surfaces exposed to air, the majority aquatic and adapted to live in ponds, lakes, reservoirs, steams, swimming pools and oceans.
Freshwater algae are of two types: planktonic and filamentous. planktonic algae, called phytoplankton, include the truly aquatic single-celled algae and the simplest filamentous or colonial forms. A heavy growth of algae may colour the water shades of green, yellow, red and black. Hey may also form water blooms or scums. They convert solar energy into food, remove CO2 from water during photosynthesis (in day time) and produce oxygen as a by product. During the night or in cloudy water, they release co2 in the water through respiration as consume O2.
Certain planktonic algae are beneficial as they can maintain biotic balance in natural aquatic environment because of their ability to produce oxygen and maintain an aerobic condition. They are the original sources of food for most fish and aquatic animals. Although planktonic algae are beneficial, their overabundance may be undesirable for many domestic and commercial water uses.
Excessive phytoplanktonic blooms often result in zooplanktonic (the microscopic animal forms) development that may deplete result in zooplanktonic the water of oxygen and lead to over fertilization or eutrophication and destruction of fish and other aquatic wild life. Dense growth of planktonic algae will shade bottom muds sufficiently to prevent germination of seeds and growth of many species of rooted submersed weeds, thus affecting the stability of the habitat
Generally, planktonic algae do not interfere with the use of surface waters or irrigation purposes. But some of them, the blue-green algae and green algae produce odours and scums that make unfit for swimming. Several of the blue-algae produce toxic substances that kill fish, birds and domestic animals.
Another group of algae called filametous algae (nanoplankton) consists of single celled joined end to end which may form single thread, branched filaments, nets, or erect stem like whorled branches or forked leaf like forms. They don’t have roots, stems or leaf as do higher plants. The important genera of the filamentous algae are: Chara, Nitella, Spirogyra, Hydrodictyon, Cladophora, Pithophora.
HYDROPHYTES-The hydrophytes, which represent more than 100 families, are vascular plants. They grow wholly or partially submersed in either fresh or saline water or in plaustrine areas. They are structurally different from mesophytes and xerophytes that grow in moisture-deficient situations. The protecting and conducting tissues of hydrophytes are less developed. They have extensive provision for aeration and buoyancy, particularly in the leaf mesophyll, ground tissue of the petiole and the cortex of the stem and root. Buoyancy is provided by aerenchyma or by air chambers. The air chambers may be either schiogenous or lysigenous, or both. Hydrophytes weeds can be grouped as submersed, emersed, marginal and floating weeds.
1- SUBMERSED WEEDS
Submersed weeds are mostly vascular plants the produce all or most of their vegetative growth beneath the water surface. Most submerged vascular weeds are seed plants and have true roots, stems and leaves. Abundance and density of these weeds is primarily dependent on depth and turbidity of water and physical characteristics of the bottom. A maximum depth of 3.5-4 m in clear waters is the limit for most of the submersed plants. They are capable of absorbing nutrients and herbicides through the leaves and stems as well as roots. They compete for nutrients with planktonic algae and decrease their production and a corresponding decrease in fish production.
The submersed weeds belong to the following genera: Potamogeton, Elodea, Myriophyllum, Ceratophyllum, Utricularia, Ranunculus, Heteratheral Alisma, Zannichellia, Lemna, etc.
2- EMERSED WEEDS
Emersed weeds are those plants rooted in the bottom muds with serial stems and leaves at or above the water surface. They grow in situations where the water level ranges from just below ground level to about half the maximum height of the plant. They differ in leaf shape, size and pint of attachment. Some of the weeds of this group have broad leaves, 5-50cm in diameter, and others have ling narrow leaves like grasses, less than 3-15cm or more in width; the latter are commonly called reeds. The leaves of emersed weeds do not rise and fall with water level as in the case of attached floating weeds. Some of the emersed weeds belong to the genera Nuphar, Nelumbo, Jussiaea, Myriophllum, etc.
3-MARGINAL WEEDS
Most marginal weeds are emersed weeds that can grow on saturated soil above the water surface; they grow from moist shoreline areas into water up to 60-90cm in depth. Marginal weed vary in size, shape and habitat species of this group are the most widely distributed rooted aquatic plant. Plants of this group are broad leaves herbs, shrubs, trees and some grasses. The important genera to which they belong are : Phragmitis, typha, Polygonum, Alternanthera, Populus, Tamarix, Cephalanthus, Juncus etc.
4-FLOATING WEEDS
Many water plants have leave that float on the water surface either singly or in rosettes .They have true root and leaves .Some are free floating and others rooted in bottom mud have floating leaves that rise or fall with the water level .They reproduce very rapidly under favorable conditions and are among the most troublesome of aquatic weed .Floating weed belong to the genera Eichhornia, Pistia, Salvinia , Lemna , Nymphaea and brasenia.
MAJOR AQUATIC WEEDS OF INDIA
Common Name Botanical Name
Water hyacinth Eichhornia crassipes
Cattails Typha angustata
Pond weed Potamogeton spp.
Hydrilla Hydrilla verticillata
Water lettuce Psitia stratiotes
Salvinia Salvinia molesta
Swamp morning glory Ipomea aquatic
Alligator weed Alternanthera spp.
Arrow head Sagittaria spp.
Spatter dock or Yellow lily Nuphar spp.
Pickerel weed Ponterdenia cordata
Reed weed Pharagmites communis
Swamp morning glory Ipomea aquatica
METHODS OF CONTROL OF AQUATIC WEEDS
Mechanical & Manual Methods
These methods employ physical forces to remove weeds:
1. Dredging- It is most common way of cleaning weeds in ponds and ditches.A dragline dredge may be equipped with a bucket or with a weed fork or other special tools. The bucket dreadge will also remove mud along with weeds while the weed fork will leave the mud. This method is labour expensive and slow.
2. Draining - Draining is an offseason weed management normally in drainage ditches by which weeds are cut manually or mechanically or spraying with a total weed killer or bottom ploughed to kill vegetative structures and root stock
3. Drying- Simple and inexpensive. The tops of under water weeds are exposed to sun by draining the water from ditches and ponds are allowed to dry. This method is effective in areas where the ponds are seasonal in use and remain dry during summers and rainy seasons. Drying is ineffective against emersed weeds and some of floating species.
4. Burning- It is used to control weeds in the banks above the water line. For obtaining the best results first searing the green vegetation and secondly after 10 -12 days with complete burning. In searing a hot flame is passed over the vegetation at such a rate that the plants wilt but are not charred. Mowing followed by burning the dried weeds may increase the effectiveness of mowing.
5. Chaining- This is relatively inexpensive method which is widely used. A heavy chain is attached between two tractors or teams on the opposite banks of ditch. As they move the chain drags over the weeds and breaks them off. Chaining is generally done only when the ditch is severely clogged. Chaining is primarily to ditches of uniform width and accessible from both sides with tractors. It is effective for cattails, tules, bur reed, arrow head and other emersed weeds.
The major disadvantages of chaining are its too laborious has to be repeated at regular intervals reverse chaining cannot be done.
6. Cutting- A mechanical weed cutter is used to cut the submersed weeds at 1 to 1.5 m deep in water. It consists of a sharp cutter bar operated hydraulically from a boat. The harvested weeds float to the water surface and removed manually or by sieve buckets.
Disadvantages of Mechanical Control Methods- They do not provide effective and economical weed control because of which repetitive operations are required. The weed fragment remaining proves as a source of new infestation.
HERBICIDES USED FOR CONTROLLING AQUATIC WEEDS
Asulam-Docks and bracken on banks.
Dalapon-Effective against grasses and cattails when applied on foliage. Draining of water before application is advisable. It is used in irrigation and drainage channels, lakes, ponds & ditch banks. Applied @ 15-20 Kg/ha for surface area. It is normally harmless to fish. However treated water is unsuitable for potable & irrigation purposes.
Dichlobenil-Effective on Elodea, watermilfoil, chara and potamageton species and is applied before weed starts growing. This is applied at the rate of 5 to 10 Kg/ha to the exposed bottom after draining water. This pre emergence application inhibits regeneration from roots and rhizomes. Water is let in after a month of treatment.
Diquat & Paraquat-These are generally used for control of floating weeds like water hyacinth and water lettuce with foliar application at 1 to 2 Kg/ha. There application in muddy water is ineffective. Efficiency is increased by combining with copper sulphate and triethanolamine.
Aqualin-The compound acrolein or acrylaldehyde has been named as aqualin. It is an active chemical attacks plant cells and kills them. It has lachrymatory effect on man and has to be sold by licensed operators.
Endothall-Aquatic weeds including algae without harming fish or aquatic life. It can be used for both submerged as well as emersed aquatic weeds. Granular formulation is Aquathall.
Copper sulphate-It is effective against many kinds of algae including chara and other species that causes scum. It is either applied as crystals or by placing crystals in a bag or towed behind a boat until the chemical is dissolved. This is applied at the rate of 0.5-1 ppm W. A concentration upto 2.5 ppm W is considered safe for human consumption while above 1 ppm W is considered unsafe for fish, but can be used for irrigation purpose.
Silvex-Effective for control of surface and emersed weeds like alligator weed, water lily, arrow head etc. prevalent in standing waters. Treated water is unsuitable for any purpose.
Method of application
Application is done by pumping the liquid into the water and allowing it to move as a blanket over and through the aquatic weeds. The herbicide may be introduced over a time period ranging from 45 min to 5 hrs. Temperature of water is important consideration. At 150C the dosage must be twice that at 28 0C. Hence the dosage must be adjusted with the plant population and temperature. In fast flowing streams, contact is not so thorough as in slow and hence, dosage must be increased when flow is greater than 10 cumec.
For proper control of weeds of wider water bodies power sprayers are mounted on motor boats. The spray range in this case will be 10 to 20 mts. With a discharge rate of 20 to 200 lts per min. For injection in stable water a hard pipe with several small holes is fitted. In flowing water the herbicide is injected from the shore itself. The herbicide is carried down the stream. During spraying the boats should maintain a speed of 2-5 Km/hr.
Biological control-
Name of Bioagent Weed controlled
Congo tilapia & Jawa tilapia Algae (chara & Nitella) & saw weeds (Najas)
Chinese grass carp or white amur
(Ctenopharyngodon idella) Aquatic plants
Common carp It is mud bottom feeder and it controls submersed aquatic weeds due to its uprooting plants and breaking up mats of algae in its search for food.
Marasmiellus inoderma Thread blight in water hyacinth
Flea beetles (Agasiches hydrophilla) Water hyacinth and Salvinia
Aquatic weed are those unwanted plants which grow in water and complete at least a part of their life cycle in water. Many aquatic plants are desirable since they may play temporarily a beneficial role in reducing agricultural, domestic and industrial pollution. Letting a crop of plants grow in a lake or pond and then killing it over a period of time, and consequently releasing nutrients back into the water, may help in fish production. However, many aquatic plans are considered weeds when they deprive human beings of all facets of efficient use of water and cause harmful effects, some of which are discussed below.
Submersed, immersed, emerged and marginal weeds in and along irrigation canals, ditches, and drainage channels impede water flow, increase evaporation, cause damage to canals and structures, and clog gates, siphons, valves, sprinkler heads bridge piers, pumps, etc.
Floating and deep-rooted submersed weeds interfere with navigation. Some of the tougher and densely growing weeds, e.g. water hyacinth and alligator weed become impenetrable and prevent boats and even steamers moving through. Submersed and floating aquatic weeds in farm ponds, village tanks and water reservoirs reduce their utility for water storage and irrigation.
Aquatic weed growth also prevents or impairs the use of inland waters for fishing. The weed assimilates large quantities of nutrients from water, thus reducing their availability for desirable planktonic algae. They cause oxygen deficiency and prevent gaseous exchange with atmosphere, resulting in an adverse effect on fish production. Excessive growth of these weeds may provide excessive cover, resulting in an overpopulation of small fish and interference with fish harvesting.
Aquatic weeds provide a suitable habitat for development of mosquitoes in impounded waters, causing malaria, filariasis and encephalitis. These weeds serve as the primary vector for the disease-causing organisms.
Aquatic weeds reduce the recreational values of lakes, tanks, streams, etc. as the water is made turbid or dirty with an undesirable odour
TYPES OF AQUATIC WEED
There are two types of aquatic plants: algae and hydrophytes.
ALGAE-Algae normally inhabit the surface of fresh and saline waters exposed to sunlight. While some kinds of algae are found in solid and on terrestrial surfaces exposed to air, the majority aquatic and adapted to live in ponds, lakes, reservoirs, steams, swimming pools and oceans.
Freshwater algae are of two types: planktonic and filamentous. planktonic algae, called phytoplankton, include the truly aquatic single-celled algae and the simplest filamentous or colonial forms. A heavy growth of algae may colour the water shades of green, yellow, red and black. Hey may also form water blooms or scums. They convert solar energy into food, remove CO2 from water during photosynthesis (in day time) and produce oxygen as a by product. During the night or in cloudy water, they release co2 in the water through respiration as consume O2.
Certain planktonic algae are beneficial as they can maintain biotic balance in natural aquatic environment because of their ability to produce oxygen and maintain an aerobic condition. They are the original sources of food for most fish and aquatic animals. Although planktonic algae are beneficial, their overabundance may be undesirable for many domestic and commercial water uses.
Excessive phytoplanktonic blooms often result in zooplanktonic (the microscopic animal forms) development that may deplete result in zooplanktonic the water of oxygen and lead to over fertilization or eutrophication and destruction of fish and other aquatic wild life. Dense growth of planktonic algae will shade bottom muds sufficiently to prevent germination of seeds and growth of many species of rooted submersed weeds, thus affecting the stability of the habitat
Generally, planktonic algae do not interfere with the use of surface waters or irrigation purposes. But some of them, the blue-green algae and green algae produce odours and scums that make unfit for swimming. Several of the blue-algae produce toxic substances that kill fish, birds and domestic animals.
Another group of algae called filametous algae (nanoplankton) consists of single celled joined end to end which may form single thread, branched filaments, nets, or erect stem like whorled branches or forked leaf like forms. They don’t have roots, stems or leaf as do higher plants. The important genera of the filamentous algae are: Chara, Nitella, Spirogyra, Hydrodictyon, Cladophora, Pithophora.
HYDROPHYTES-The hydrophytes, which represent more than 100 families, are vascular plants. They grow wholly or partially submersed in either fresh or saline water or in plaustrine areas. They are structurally different from mesophytes and xerophytes that grow in moisture-deficient situations. The protecting and conducting tissues of hydrophytes are less developed. They have extensive provision for aeration and buoyancy, particularly in the leaf mesophyll, ground tissue of the petiole and the cortex of the stem and root. Buoyancy is provided by aerenchyma or by air chambers. The air chambers may be either schiogenous or lysigenous, or both. Hydrophytes weeds can be grouped as submersed, emersed, marginal and floating weeds.
1- SUBMERSED WEEDS
Submersed weeds are mostly vascular plants the produce all or most of their vegetative growth beneath the water surface. Most submerged vascular weeds are seed plants and have true roots, stems and leaves. Abundance and density of these weeds is primarily dependent on depth and turbidity of water and physical characteristics of the bottom. A maximum depth of 3.5-4 m in clear waters is the limit for most of the submersed plants. They are capable of absorbing nutrients and herbicides through the leaves and stems as well as roots. They compete for nutrients with planktonic algae and decrease their production and a corresponding decrease in fish production.
The submersed weeds belong to the following genera: Potamogeton, Elodea, Myriophyllum, Ceratophyllum, Utricularia, Ranunculus, Heteratheral Alisma, Zannichellia, Lemna, etc.
2- EMERSED WEEDS
Emersed weeds are those plants rooted in the bottom muds with serial stems and leaves at or above the water surface. They grow in situations where the water level ranges from just below ground level to about half the maximum height of the plant. They differ in leaf shape, size and pint of attachment. Some of the weeds of this group have broad leaves, 5-50cm in diameter, and others have ling narrow leaves like grasses, less than 3-15cm or more in width; the latter are commonly called reeds. The leaves of emersed weeds do not rise and fall with water level as in the case of attached floating weeds. Some of the emersed weeds belong to the genera Nuphar, Nelumbo, Jussiaea, Myriophllum, etc.
3-MARGINAL WEEDS
Most marginal weeds are emersed weeds that can grow on saturated soil above the water surface; they grow from moist shoreline areas into water up to 60-90cm in depth. Marginal weed vary in size, shape and habitat species of this group are the most widely distributed rooted aquatic plant. Plants of this group are broad leaves herbs, shrubs, trees and some grasses. The important genera to which they belong are : Phragmitis, typha, Polygonum, Alternanthera, Populus, Tamarix, Cephalanthus, Juncus etc.
4-FLOATING WEEDS
Many water plants have leave that float on the water surface either singly or in rosettes .They have true root and leaves .Some are free floating and others rooted in bottom mud have floating leaves that rise or fall with the water level .They reproduce very rapidly under favorable conditions and are among the most troublesome of aquatic weed .Floating weed belong to the genera Eichhornia, Pistia, Salvinia , Lemna , Nymphaea and brasenia.
MAJOR AQUATIC WEEDS OF INDIA
Common Name Botanical Name
Water hyacinth Eichhornia crassipes
Cattails Typha angustata
Pond weed Potamogeton spp.
Hydrilla Hydrilla verticillata
Water lettuce Psitia stratiotes
Salvinia Salvinia molesta
Swamp morning glory Ipomea aquatic
Alligator weed Alternanthera spp.
Arrow head Sagittaria spp.
Spatter dock or Yellow lily Nuphar spp.
Pickerel weed Ponterdenia cordata
Reed weed Pharagmites communis
Swamp morning glory Ipomea aquatica
METHODS OF CONTROL OF AQUATIC WEEDS
Mechanical & Manual Methods
These methods employ physical forces to remove weeds:
1. Dredging- It is most common way of cleaning weeds in ponds and ditches.A dragline dredge may be equipped with a bucket or with a weed fork or other special tools. The bucket dreadge will also remove mud along with weeds while the weed fork will leave the mud. This method is labour expensive and slow.
2. Draining - Draining is an offseason weed management normally in drainage ditches by which weeds are cut manually or mechanically or spraying with a total weed killer or bottom ploughed to kill vegetative structures and root stock
3. Drying- Simple and inexpensive. The tops of under water weeds are exposed to sun by draining the water from ditches and ponds are allowed to dry. This method is effective in areas where the ponds are seasonal in use and remain dry during summers and rainy seasons. Drying is ineffective against emersed weeds and some of floating species.
4. Burning- It is used to control weeds in the banks above the water line. For obtaining the best results first searing the green vegetation and secondly after 10 -12 days with complete burning. In searing a hot flame is passed over the vegetation at such a rate that the plants wilt but are not charred. Mowing followed by burning the dried weeds may increase the effectiveness of mowing.
5. Chaining- This is relatively inexpensive method which is widely used. A heavy chain is attached between two tractors or teams on the opposite banks of ditch. As they move the chain drags over the weeds and breaks them off. Chaining is generally done only when the ditch is severely clogged. Chaining is primarily to ditches of uniform width and accessible from both sides with tractors. It is effective for cattails, tules, bur reed, arrow head and other emersed weeds.
The major disadvantages of chaining are its too laborious has to be repeated at regular intervals reverse chaining cannot be done.
6. Cutting- A mechanical weed cutter is used to cut the submersed weeds at 1 to 1.5 m deep in water. It consists of a sharp cutter bar operated hydraulically from a boat. The harvested weeds float to the water surface and removed manually or by sieve buckets.
Disadvantages of Mechanical Control Methods- They do not provide effective and economical weed control because of which repetitive operations are required. The weed fragment remaining proves as a source of new infestation.
HERBICIDES USED FOR CONTROLLING AQUATIC WEEDS
Asulam-Docks and bracken on banks.
Dalapon-Effective against grasses and cattails when applied on foliage. Draining of water before application is advisable. It is used in irrigation and drainage channels, lakes, ponds & ditch banks. Applied @ 15-20 Kg/ha for surface area. It is normally harmless to fish. However treated water is unsuitable for potable & irrigation purposes.
Dichlobenil-Effective on Elodea, watermilfoil, chara and potamageton species and is applied before weed starts growing. This is applied at the rate of 5 to 10 Kg/ha to the exposed bottom after draining water. This pre emergence application inhibits regeneration from roots and rhizomes. Water is let in after a month of treatment.
Diquat & Paraquat-These are generally used for control of floating weeds like water hyacinth and water lettuce with foliar application at 1 to 2 Kg/ha. There application in muddy water is ineffective. Efficiency is increased by combining with copper sulphate and triethanolamine.
Aqualin-The compound acrolein or acrylaldehyde has been named as aqualin. It is an active chemical attacks plant cells and kills them. It has lachrymatory effect on man and has to be sold by licensed operators.
Endothall-Aquatic weeds including algae without harming fish or aquatic life. It can be used for both submerged as well as emersed aquatic weeds. Granular formulation is Aquathall.
Copper sulphate-It is effective against many kinds of algae including chara and other species that causes scum. It is either applied as crystals or by placing crystals in a bag or towed behind a boat until the chemical is dissolved. This is applied at the rate of 0.5-1 ppm W. A concentration upto 2.5 ppm W is considered safe for human consumption while above 1 ppm W is considered unsafe for fish, but can be used for irrigation purpose.
Silvex-Effective for control of surface and emersed weeds like alligator weed, water lily, arrow head etc. prevalent in standing waters. Treated water is unsuitable for any purpose.
Method of application
Application is done by pumping the liquid into the water and allowing it to move as a blanket over and through the aquatic weeds. The herbicide may be introduced over a time period ranging from 45 min to 5 hrs. Temperature of water is important consideration. At 150C the dosage must be twice that at 28 0C. Hence the dosage must be adjusted with the plant population and temperature. In fast flowing streams, contact is not so thorough as in slow and hence, dosage must be increased when flow is greater than 10 cumec.
For proper control of weeds of wider water bodies power sprayers are mounted on motor boats. The spray range in this case will be 10 to 20 mts. With a discharge rate of 20 to 200 lts per min. For injection in stable water a hard pipe with several small holes is fitted. In flowing water the herbicide is injected from the shore itself. The herbicide is carried down the stream. During spraying the boats should maintain a speed of 2-5 Km/hr.
Biological control-
Name of Bioagent Weed controlled
Congo tilapia & Jawa tilapia Algae (chara & Nitella) & saw weeds (Najas)
Chinese grass carp or white amur
(Ctenopharyngodon idella) Aquatic plants
Common carp It is mud bottom feeder and it controls submersed aquatic weeds due to its uprooting plants and breaking up mats of algae in its search for food.
Marasmiellus inoderma Thread blight in water hyacinth
Flea beetles (Agasiches hydrophilla) Water hyacinth and Salvinia
Cultivation or Package of practise for Fodder Sorghum (Sorghum bicolor (L)) Moench
Botany-
Annual, erect, single stalked or tillering; leaves alternate, ligules short membranous, inflorescence a panicle, contracted or loose, spikelets in clusters of 2 or 3 one sessile and hermaphrodite and the other/(s) pedicelled staminate or sterile; stamens three; stigmas two; styles terminal; fruit is a caryopsis.
Growth Stages-
Sorghum has five distinct growth stages:
1. Seedling Stage- Germination takes place in 4-5DAS. Emergence of coleoptiles indicates seedling stage.
2. Flag Leaf Stage-3-4 leaves with fully expended leaf area. Stage reaches in 40-55 DAS.
3. Boot Stage-Ear head covered within sheath i.e. under flag leaf stage reaches in 45-60 DAS.
4. Soft Dough-Endosperm filled with watery fluid. It’s called milky stage. Stage reaches in 70-85DAS.
5. Physiological Maturity- Grain with maximum accumulation of dry matter. Stage reaches in 85-95DAS.
Climate:-
It is a plant of warm climate. It remains dormant under unfavorable conditions, leaves posses waxy coating and presence of motor cells in leaves rolls the leaves under moisture deficit conditions. It is also posses more no of secondary roots/ unit of primary roots. Thus crop can withstand drought better than maize. Crop is grown in areas receiving 800-1000mm annual rainfall isohyets. High rainfall is undesirable though crop can withstand water logging. It is a Short day plant and a 10 hr photoperiod enhances early flowering. Increase in day length delay flowering and benefit dry matter production. During drought the cyanide content remains high.
Minimum temperature required for germination 7-10 degree C
Optimum temperature for growth 25-30 degree C
Soil Requirement-
The crop grows on every type of soil except very sandy soil. It is predominantly grown in vertisols. As a rainfed crop it is better suited to heavier soils retentive of moisture. It grows best in deep alluvial soils with irrigation. Black cotton soils of central India are considered as best soils for its cultivation. It can withstand moderate salinity.
Field Preparation-
Sorghum is a shallow rooted crop and does not require deep cultivation. 2 to 4 operations by desi plough or blade harrow, alternatively 2 to 4 times harrowing to pulverize the soil to a fine tith OR deep summer ploughing with mould board plough and two ploughings by country plough with the onset of monsoon are enough to prepare the land for sowing. Crop is grown in pH range of 7 to 8.5.
Manures & Fertilizers
The application of FYM @ 10 t/ha for drylands and 25 t/ha in irrigated areas plus 50 Kg Ammonium Sulphate at the time of planting and remaining 50 Kg at knee height stage (30-35 DAS) proves beneficial (Top dressing only when moisture is adequate). Nitrogenous fertilizers increased forage yields significantly. Forage yield is good when N coupled with P and K is supplied. Hence fertilization with balanced N, P & K is very important.
In irrigated are 100:80:50 Kg NPK/ha is applied. Source of fertilizer’s are urea, SSP & MOP. For multicut varieties 75-100 Kg urea along with 20 Kg P2O5 and 20 Kg MOP is applied after every cut.
Under dry farming conditions 50:40-80:40 Kg NPK/ha is applied. Instead of fertilizer dressing, 15 to 20 kg urea dissolved in 750 to 1000 lts of water may be sprayed every fortnight after establishment of crop for quick utilization of fertilizers and better succulence of crop. Care is taken not to apply excess of N fertilizers for free accumulation of nitrates.
In case of Zinc deficiency apply 10-15 kg of ZnSO4 or 0.2 % ZnSO4 with half quantity of lime to prevent burning of leaves. Iron chlorosis is a common problem is sorghum as it is very sensitive to iron deficiency. Spraying ferrous sulphate with lime is efficient to overcome deficiency.
Bio Fertilizers- Seed inoculation with Azospirillum brasilense.
Sowing Time-
Sorghum can be grown in Kharif (June-September), Maghi (late Kharif) September - December), Rabi (October-January) and in summer (January - May). Summer crops can be multicut in nature. Sowing of seed crop is so adjusted that it flowers at a time when there is no rains.
Seed Rate-
Since close spacing is necessary seed rate is usually higher 20-25 kg/ha for bold seeded varieties & 10-15 kg/ha small seeded varieties. Sometimes more than 100 kg/ha seed rate is used for producing thin stalked stems for hay making or to feed it without chaffing. In mixtures 25 kg sorghum and 20 Kg of cowpea or guar seeds/ha may be sown either in crosswise lines or 2 lines of sorghum alternated with 2 lines of legumes.
Spacing- For fodder crop spacing is kept Row to row: 25 to 30cm &Plant to plant: 10 to 15 cm.
Plant population-3.33 lakh plants /ha for fodders are considered optimum while for grain sorghum a plant population of 1.5-2.0 lakh plants /ha is considered optimum.
Method of Sowing-
Generally seeds are sown by broadcasting and covered with desi plough or harrow to achieve quick sowing in accordance with monsoon. The seeds must not be sown at 2-5cm depth. If germination is gappy seedlings from thick patches can be uprooted and transplanted in the evening.
Irrigation-
Sorghum is drought tolerant. An irrigated fodder crop of sorghum needs about 50 to 70cm of water in 5 to 7 irrigations. In hot and dry summers the crop requires irrigation every fortnight, but during rains excess water should be drained out of the field. During the post monsoon season irrigation water may be required every 3 weeks. Early seedling stage and flower primordial stages are considered most critical for moisture stress. Depth of irrigation is generally 6-8cm and water requirement of crop is around 80-480mm. Crop should be irrigated after each cut for better regeneration.
Cutting Management-
At the flowering stage the herbage contains low to moderate amounts of HCN. In young herbage, the HCN content may be as high as 750 ppm or more which is dangerous to animals. The plants at heading stage can be safely grazed or fed. So harvesting is to be done after 50 % flowering. After this stage crude protein content, digestibility, Ca & P content decreases sharply however crude fibre content increases. The stems become hard and woody with maturity. In multicut varieties, the first cut is taken after 2 months and subsequent cuts after 35 to 40 days. A long duration variety cut 2 to 3 times at 15 cm, better yields of quality forage then cut once at flowering. Crop should be cut 5-8 cm above the ground level for fast sprouting.
Sorghum Poisoning-
Young sorghum plants (30-40 days old) contain poisonous chemical cynogenic glucoside ‘Dhurrin’. ‘Dhurrin’ in the stomach of animals is converted to hydrocyanic acid. Thus when cattle, sheep and goats graze such green and growing sorghum crop (about 5 Kg) may result in hydrocyanic acid (HCN) or Prussic acid poisoning leading to carcinogenic death of animal. HCN content is more in leaves. Concentration of HCN is more in morning and in summers. Danger of HCN poisoning is greatest at immature stages of sorghum growth and decreases with maturity. The toxic limit of HCN is 200ppm, concentration decreases after 50 days. Hay and silage are generally free from HCN.HCN levels are most potent in:
young plants under 6 weeks old;
young regrowth;
plants stressed due to drought;
high soil nitrogen level;
Imbalance between soil nitrogen and phosphorus.
Generally, cutting the plants and chopping, and sun-curing can reduce HCN levels, because the HCN can evaporate with the loss in forage moisture.
Management to reduce HCN poisoning:
Do not turn hungry livestock out on lush regrowth of sorghum. Feed some dry fodder first, then turn out in the afternoon;
Do not graze until the regrowth is 18 to 24 inches tall;
Drying or ensiling or allowing the forage to mature will reduce its HCN content.
Sorghum or Yellow Effect or Soil Sickness-
The nutrient status of soil is exhausted by growing sorghum. The crop residue of sorghum having wide C: N ratio takes a long time to decompose. During this process of decomposition, part of soil nitrogen is temporarily immobilized affecting the succeeding crop. Such effect is more pronounced in low fertile soil causing to temporary deficiency of nitrogen in the soil for succeeding crop. To reduce sorghum effect, 25% more nitrogen is applied at the time of first fertilizer dose of the succeeding crop. It hastens the process of decomposition and overcomes the immobilized nitrogen. Ragi is the exception because its residue decomposes rapidly resulting in mineralization of soil nitrogen.
Weeds & Weed Control-
Sorghum is badly infested with grassy and broad leaf weeds because of congenial weather. 15-45 DAS of crop growth is critical period of crop weed competition. Sorghum halepense barru mimics with sorghum particularly before appearance of inflorescence.Inter row weeds can be controlled mechanically by running blade harrow, but intra row weeds remain.Striga (Striga lutea) causes 15-100 % loss depending on severity of infestation.
Constraints of Production-
Lack of demand for human consumption, non availability of improved seeds, cultivation of crop on poor soils and low acerage under HYV. Poor emphasis on plant protection and moisture stress are other factors leading to poor yields.
Annual, erect, single stalked or tillering; leaves alternate, ligules short membranous, inflorescence a panicle, contracted or loose, spikelets in clusters of 2 or 3 one sessile and hermaphrodite and the other/(s) pedicelled staminate or sterile; stamens three; stigmas two; styles terminal; fruit is a caryopsis.
Growth Stages-
Sorghum has five distinct growth stages:
1. Seedling Stage- Germination takes place in 4-5DAS. Emergence of coleoptiles indicates seedling stage.
2. Flag Leaf Stage-3-4 leaves with fully expended leaf area. Stage reaches in 40-55 DAS.
3. Boot Stage-Ear head covered within sheath i.e. under flag leaf stage reaches in 45-60 DAS.
4. Soft Dough-Endosperm filled with watery fluid. It’s called milky stage. Stage reaches in 70-85DAS.
5. Physiological Maturity- Grain with maximum accumulation of dry matter. Stage reaches in 85-95DAS.
Climate:-
It is a plant of warm climate. It remains dormant under unfavorable conditions, leaves posses waxy coating and presence of motor cells in leaves rolls the leaves under moisture deficit conditions. It is also posses more no of secondary roots/ unit of primary roots. Thus crop can withstand drought better than maize. Crop is grown in areas receiving 800-1000mm annual rainfall isohyets. High rainfall is undesirable though crop can withstand water logging. It is a Short day plant and a 10 hr photoperiod enhances early flowering. Increase in day length delay flowering and benefit dry matter production. During drought the cyanide content remains high.
Minimum temperature required for germination 7-10 degree C
Optimum temperature for growth 25-30 degree C
Soil Requirement-
The crop grows on every type of soil except very sandy soil. It is predominantly grown in vertisols. As a rainfed crop it is better suited to heavier soils retentive of moisture. It grows best in deep alluvial soils with irrigation. Black cotton soils of central India are considered as best soils for its cultivation. It can withstand moderate salinity.
Field Preparation-
Sorghum is a shallow rooted crop and does not require deep cultivation. 2 to 4 operations by desi plough or blade harrow, alternatively 2 to 4 times harrowing to pulverize the soil to a fine tith OR deep summer ploughing with mould board plough and two ploughings by country plough with the onset of monsoon are enough to prepare the land for sowing. Crop is grown in pH range of 7 to 8.5.
Manures & Fertilizers
The application of FYM @ 10 t/ha for drylands and 25 t/ha in irrigated areas plus 50 Kg Ammonium Sulphate at the time of planting and remaining 50 Kg at knee height stage (30-35 DAS) proves beneficial (Top dressing only when moisture is adequate). Nitrogenous fertilizers increased forage yields significantly. Forage yield is good when N coupled with P and K is supplied. Hence fertilization with balanced N, P & K is very important.
In irrigated are 100:80:50 Kg NPK/ha is applied. Source of fertilizer’s are urea, SSP & MOP. For multicut varieties 75-100 Kg urea along with 20 Kg P2O5 and 20 Kg MOP is applied after every cut.
Under dry farming conditions 50:40-80:40 Kg NPK/ha is applied. Instead of fertilizer dressing, 15 to 20 kg urea dissolved in 750 to 1000 lts of water may be sprayed every fortnight after establishment of crop for quick utilization of fertilizers and better succulence of crop. Care is taken not to apply excess of N fertilizers for free accumulation of nitrates.
In case of Zinc deficiency apply 10-15 kg of ZnSO4 or 0.2 % ZnSO4 with half quantity of lime to prevent burning of leaves. Iron chlorosis is a common problem is sorghum as it is very sensitive to iron deficiency. Spraying ferrous sulphate with lime is efficient to overcome deficiency.
Bio Fertilizers- Seed inoculation with Azospirillum brasilense.
Sowing Time-
Sorghum can be grown in Kharif (June-September), Maghi (late Kharif) September - December), Rabi (October-January) and in summer (January - May). Summer crops can be multicut in nature. Sowing of seed crop is so adjusted that it flowers at a time when there is no rains.
Seed Rate-
Since close spacing is necessary seed rate is usually higher 20-25 kg/ha for bold seeded varieties & 10-15 kg/ha small seeded varieties. Sometimes more than 100 kg/ha seed rate is used for producing thin stalked stems for hay making or to feed it without chaffing. In mixtures 25 kg sorghum and 20 Kg of cowpea or guar seeds/ha may be sown either in crosswise lines or 2 lines of sorghum alternated with 2 lines of legumes.
Spacing- For fodder crop spacing is kept Row to row: 25 to 30cm &Plant to plant: 10 to 15 cm.
Plant population-3.33 lakh plants /ha for fodders are considered optimum while for grain sorghum a plant population of 1.5-2.0 lakh plants /ha is considered optimum.
Method of Sowing-
Generally seeds are sown by broadcasting and covered with desi plough or harrow to achieve quick sowing in accordance with monsoon. The seeds must not be sown at 2-5cm depth. If germination is gappy seedlings from thick patches can be uprooted and transplanted in the evening.
Irrigation-
Sorghum is drought tolerant. An irrigated fodder crop of sorghum needs about 50 to 70cm of water in 5 to 7 irrigations. In hot and dry summers the crop requires irrigation every fortnight, but during rains excess water should be drained out of the field. During the post monsoon season irrigation water may be required every 3 weeks. Early seedling stage and flower primordial stages are considered most critical for moisture stress. Depth of irrigation is generally 6-8cm and water requirement of crop is around 80-480mm. Crop should be irrigated after each cut for better regeneration.
Cutting Management-
At the flowering stage the herbage contains low to moderate amounts of HCN. In young herbage, the HCN content may be as high as 750 ppm or more which is dangerous to animals. The plants at heading stage can be safely grazed or fed. So harvesting is to be done after 50 % flowering. After this stage crude protein content, digestibility, Ca & P content decreases sharply however crude fibre content increases. The stems become hard and woody with maturity. In multicut varieties, the first cut is taken after 2 months and subsequent cuts after 35 to 40 days. A long duration variety cut 2 to 3 times at 15 cm, better yields of quality forage then cut once at flowering. Crop should be cut 5-8 cm above the ground level for fast sprouting.
Sorghum Poisoning-
Young sorghum plants (30-40 days old) contain poisonous chemical cynogenic glucoside ‘Dhurrin’. ‘Dhurrin’ in the stomach of animals is converted to hydrocyanic acid. Thus when cattle, sheep and goats graze such green and growing sorghum crop (about 5 Kg) may result in hydrocyanic acid (HCN) or Prussic acid poisoning leading to carcinogenic death of animal. HCN content is more in leaves. Concentration of HCN is more in morning and in summers. Danger of HCN poisoning is greatest at immature stages of sorghum growth and decreases with maturity. The toxic limit of HCN is 200ppm, concentration decreases after 50 days. Hay and silage are generally free from HCN.HCN levels are most potent in:
young plants under 6 weeks old;
young regrowth;
plants stressed due to drought;
high soil nitrogen level;
Imbalance between soil nitrogen and phosphorus.
Generally, cutting the plants and chopping, and sun-curing can reduce HCN levels, because the HCN can evaporate with the loss in forage moisture.
Management to reduce HCN poisoning:
Do not turn hungry livestock out on lush regrowth of sorghum. Feed some dry fodder first, then turn out in the afternoon;
Do not graze until the regrowth is 18 to 24 inches tall;
Drying or ensiling or allowing the forage to mature will reduce its HCN content.
Sorghum or Yellow Effect or Soil Sickness-
The nutrient status of soil is exhausted by growing sorghum. The crop residue of sorghum having wide C: N ratio takes a long time to decompose. During this process of decomposition, part of soil nitrogen is temporarily immobilized affecting the succeeding crop. Such effect is more pronounced in low fertile soil causing to temporary deficiency of nitrogen in the soil for succeeding crop. To reduce sorghum effect, 25% more nitrogen is applied at the time of first fertilizer dose of the succeeding crop. It hastens the process of decomposition and overcomes the immobilized nitrogen. Ragi is the exception because its residue decomposes rapidly resulting in mineralization of soil nitrogen.
Weeds & Weed Control-
Sorghum is badly infested with grassy and broad leaf weeds because of congenial weather. 15-45 DAS of crop growth is critical period of crop weed competition. Sorghum halepense barru mimics with sorghum particularly before appearance of inflorescence.Inter row weeds can be controlled mechanically by running blade harrow, but intra row weeds remain.Striga (Striga lutea) causes 15-100 % loss depending on severity of infestation.
Constraints of Production-
Lack of demand for human consumption, non availability of improved seeds, cultivation of crop on poor soils and low acerage under HYV. Poor emphasis on plant protection and moisture stress are other factors leading to poor yields.
Tuesday, April 14, 2009
Aberrant weather situations and Contengency Crop Planning
Dryland Agriculture an Introduction:-
At present there is a talk about second green revolution. The International Food Policy Research Institute, Washington, opined”with the rising demand for food in coming decades, India will have to depend on the rainfed areas to help increase supply”. India contains about 47 mha as drylands out of 108 mha of total rainfed are which amounts nearly 43 %. The semi arid tracts are not only large but also agriculturally important. In India, such tracts cover 84 districts, spreading over 47 mha which is more than one-third net sown area. But their contribution to total food grain production is about a fifth in the country.
WEATHER: MOST VARIABLE FACTOR IN DRYLAND AREAS
Unfavourable deviated weather from the normally expected one is called aberrant weather. Aberrant weather is a common feature of rainfed agriculture. Crop production in dry areas is mainly dependent upon rainfall, which is received during the south west monsoon. The rainfall is seasonal, erratic and highly variable with space & time. Vagaries of monsoon rains and breaks of varying duration are most common in India. Three important aberrations in the rainfall behavior have been commonly observed. These are:
• The commencement of rains may be quite early or considerably delayed.
• There may be prolonged breaks during the southwest monsoon season during which most of the dryland crops are grown
• Rains may terminate earlier than normal cessation date or may continue beyond the normal rainy season.
Anomalies in the distribution of south west monsoon rainfall are well known. Based on the analysis of historical rainfall records, have brought out the following main features of rainfall distribution in India.
• There is large variation in the dates of commencement of the southwest monsoon rainfall from year to year in different parts of the country.
• The monsoon rainfall is of sequential nature with dry spells interspersed with wet spells, dry spells extending from few days to several weeks.
• There is a large year to year variation in the dates of cessation of south west monsoon rainfall in different parts of country.
• There is variation in the quantum of rainfall received from year to year and t he coefficient of variation of rainfall increases with decrease in monsoon rainfall.
• High intensity rainfall occurs in association with the movement of cyclones/depressions resulting in sizeable loss of rain water through run-off and deep drainage.
Weather is the most variable factor in rainfed crop production. It is the one which can be least controlled. However, various approaches, often referred as contingent plans, have been evolved over the years, for efficient weather management. The infrastructure requirements have to be developed and established by the government and other agencies as people themselves will not be in a position to adopt contingency measures more effectively because of their poor resource base. Some of the management options that can be adopted to mellow down the adverse effects of aberrant weather are discussed here.
CONTINGENCY CROP PLANNING
Contingency planning refers to mitigate any unexpected, unusual, unfavourable and hence unwanted accidental weather situations occurring at any time without prior knowledge at any time before the crops are sown or even after the crops are sown. The contingency crop planning therefore is proposed to mitigate such situation through the choice of appropriate crop and varieties, cropping systems or other necessary relevant farm practices. To develop a contingency plan for an area, a detailed study of the rainfall data should be done first. Based on this rainfall data, the planning should be done. In any areas generally following rainfall situation may occur:
1. Early onset of monsoon.
2. Normal onset of monsoon followed by immediate prolonged dry spell.
3. Delayed onset of monsoon.
4. Early cessation of rains.
5. Extended monsoon.
LATE ONSET OF MONSOON
During some of the years the onset of south west monsoon gets delayed so that the crops/varieties which are regularly grown in the region cannot be sown in time. Delayed sowing of the crops can lead to reduced and even uneconomical crop yields. Under these circumstances, two management options are available.
1. Transplantation-This is the surer way of compensating the delay in the commencement of sowing rains, through transplantation is labour intensive operation. Extensive studies carried out indicated that both long and medium duration varieties of finger millet should be transplanted for maintaining yield levels whenever sowing is delayed.
2. Alternate Crops/Varieties-certain crops/varieties can perform better even if sown late in the season. Depending on the receipt of rains, such crops and varieties can be selected. Castor (Aruna) is more remunerative in red soils of telengana (AP) then pigeonpea under late sown conditions. Sunflower, because of its shorter duration, performs better than groundnut when sowings are delayed beyond September first fortnight in relatively deeper red soils. In western Rajasthan, short duration green gram and cowpea are more remunerative than pearl millet when sown late.
DRY SPELL IMMEDIATELY AFTER SOWING
Dry spells are common in dryland agriculture. Due to dry spell after sowing of crop it might result in poor germination due to soil crusting, withering of seedlings and poor establishment of crop stand. The adverse effect of moisture stress should be mitigated to avoid total crop failure. It is necessary to maintain proper plant stand to ensure better yield. Therefore it is better to resow the crop than to continue with inadequate plant stand.
MID SEASON CORRECTION OR DRY SPELLS DURING CROP PERIOD
After sowing of crops and early growth any unexpected or unfavourable weather abnormality like long dry spell of 3 to 6 weeks, drought or early cessation of monsoon may occur. Unexpected or accidental occurrence of unfavourable weather after sowing is contingency and crop planning to overcome this contingency is called contingency crop planning. To mitigate the damaging effects of droughts after sowing of crop following mid season corrections are recommended:
1. Ratooning-The rate of soil moisture depletion increases with increasing leaf area. If drought occurs at 40- 50 DAS, reduction in leaf area either by rationing or thinning plant population can mitigate the adverse effects of drought. Sorghum and pearl millet responds to rationing. 2 % urea sprays after drought period is useful for indeterminate crops like castor, pigeon pea and groundnut.
2. Mulching-If the break in monsoon is very brief, soil mulching was found to be tool in extending the period of storage of water in the soil profile due to reduced heat load on the soil and hence the evaporation losses which in turn leads to extended periods of water availability. Repeated intercultivations in black soils results in formation of soil mulch on the surface. It acts as barrier to evaporation loss from soil profile. Deep cracks formed due to drought increases the loss of stored water by evaporation. Soil mulch minimizes deep cracking leading to reduced evaporation losses.
3. Thinning-If drought occurs during pre-flowering stage thinning is useful. Every third plant or alternate row may be removed to reduce the soil moisture loss and preserve it. Moisture stress of 35-50 days can be lessened by such thinning.
4. Weed Control-Weed control is very essential to save the crop from onslaught of drought as weeds rob soil moisture and nutrients as well.
5. Rain water harvesting and recycling-In situ water harvesting and / or runoff recycling are the potent measures for crop life saving during the periods of moisture stress. There is no control over the receipt of rainwater but it can be managed in a way better what is being done at present after it is received. Supplementary irrigation provided to the crop through rainwater harvesting and recycling particularly during the grain formation stage will be very much rewarding. Run-off recycling holds immense prospects in deep black soil where the seepage losses are very less. High intensity rains are quite common during the rainy season contributing 75% of seasonal rainfall. The inevitable runoff (10-40% of the total rainfall) could be stored in dugout ponds of appropriate sizes and recycled to the donor area, in the event of severe moisture stress.
6. Stripping of crop leaves- Generally, photosynthesis occurs in the upper 3-4 leaves. Hence excluding these leaves, lower leaves from the plant may be removed to reduce transpirational losses.
7. Intercropping and risk distribution-Application of meteorological information in terms of the frequency and probability of breaks in monsoon rains can be made to select a combination of crops of different durations in such a way that there is time lag in the occurrence of their grow for appropriate intercropping systems. The choice of intercrop depends upon the pattern of rainfall. There are 3 possibilities as:
1. Rainfall more uncertain in the early part of season.
2. Rainfall more uncertain in the later part of season.
3. Rainfall more or less uniformly distributed (in other words, the risk is uniformly distributed).
Region System
Hisar Pearlmillet + Cowpea
Agra Pearlmillet+ greengram
Banglore Pigeonpea + Cowpea
Hyderabad Sorghum + pigeonpea
Akola Sorghum + greengram
EARLY WITHDRAWAL OF MONSOON
Early withdrawal of monsoon before rabi seeding leads to problem of crop stand establishment and terminal drought. Therefore, rabi seeding should be as far as possible in early September to avoid the above two problems. All the suggested measures to mitigate the adverse effect of prolonged dry spells during crop period are necessary to overcome the soil moisture stress during the early withdrawal of monsoon.
EXTENDED MONSOON
Extended monsoon is seldom a problem in dryland agriculture. It benefits long duration kharif crops taken as a component crops in intercropping system and is also advantageous for rabi crops.
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References:
1-Principles & Practices of Dryland Agriculture- K. Govindan & V. Thirumurugan
2-Dryland Agriculture- S.C. Panda
3-Sustainable Development of Dryland Agriculture in India- Editor R.P. Singh
4-Principles of Agronomy-S.R. Reddy
5-Handbook of Agriculture- ICAR publications
At present there is a talk about second green revolution. The International Food Policy Research Institute, Washington, opined”with the rising demand for food in coming decades, India will have to depend on the rainfed areas to help increase supply”. India contains about 47 mha as drylands out of 108 mha of total rainfed are which amounts nearly 43 %. The semi arid tracts are not only large but also agriculturally important. In India, such tracts cover 84 districts, spreading over 47 mha which is more than one-third net sown area. But their contribution to total food grain production is about a fifth in the country.
WEATHER: MOST VARIABLE FACTOR IN DRYLAND AREAS
Unfavourable deviated weather from the normally expected one is called aberrant weather. Aberrant weather is a common feature of rainfed agriculture. Crop production in dry areas is mainly dependent upon rainfall, which is received during the south west monsoon. The rainfall is seasonal, erratic and highly variable with space & time. Vagaries of monsoon rains and breaks of varying duration are most common in India. Three important aberrations in the rainfall behavior have been commonly observed. These are:
• The commencement of rains may be quite early or considerably delayed.
• There may be prolonged breaks during the southwest monsoon season during which most of the dryland crops are grown
• Rains may terminate earlier than normal cessation date or may continue beyond the normal rainy season.
Anomalies in the distribution of south west monsoon rainfall are well known. Based on the analysis of historical rainfall records, have brought out the following main features of rainfall distribution in India.
• There is large variation in the dates of commencement of the southwest monsoon rainfall from year to year in different parts of the country.
• The monsoon rainfall is of sequential nature with dry spells interspersed with wet spells, dry spells extending from few days to several weeks.
• There is a large year to year variation in the dates of cessation of south west monsoon rainfall in different parts of country.
• There is variation in the quantum of rainfall received from year to year and t he coefficient of variation of rainfall increases with decrease in monsoon rainfall.
• High intensity rainfall occurs in association with the movement of cyclones/depressions resulting in sizeable loss of rain water through run-off and deep drainage.
Weather is the most variable factor in rainfed crop production. It is the one which can be least controlled. However, various approaches, often referred as contingent plans, have been evolved over the years, for efficient weather management. The infrastructure requirements have to be developed and established by the government and other agencies as people themselves will not be in a position to adopt contingency measures more effectively because of their poor resource base. Some of the management options that can be adopted to mellow down the adverse effects of aberrant weather are discussed here.
CONTINGENCY CROP PLANNING
Contingency planning refers to mitigate any unexpected, unusual, unfavourable and hence unwanted accidental weather situations occurring at any time without prior knowledge at any time before the crops are sown or even after the crops are sown. The contingency crop planning therefore is proposed to mitigate such situation through the choice of appropriate crop and varieties, cropping systems or other necessary relevant farm practices. To develop a contingency plan for an area, a detailed study of the rainfall data should be done first. Based on this rainfall data, the planning should be done. In any areas generally following rainfall situation may occur:
1. Early onset of monsoon.
2. Normal onset of monsoon followed by immediate prolonged dry spell.
3. Delayed onset of monsoon.
4. Early cessation of rains.
5. Extended monsoon.
LATE ONSET OF MONSOON
During some of the years the onset of south west monsoon gets delayed so that the crops/varieties which are regularly grown in the region cannot be sown in time. Delayed sowing of the crops can lead to reduced and even uneconomical crop yields. Under these circumstances, two management options are available.
1. Transplantation-This is the surer way of compensating the delay in the commencement of sowing rains, through transplantation is labour intensive operation. Extensive studies carried out indicated that both long and medium duration varieties of finger millet should be transplanted for maintaining yield levels whenever sowing is delayed.
2. Alternate Crops/Varieties-certain crops/varieties can perform better even if sown late in the season. Depending on the receipt of rains, such crops and varieties can be selected. Castor (Aruna) is more remunerative in red soils of telengana (AP) then pigeonpea under late sown conditions. Sunflower, because of its shorter duration, performs better than groundnut when sowings are delayed beyond September first fortnight in relatively deeper red soils. In western Rajasthan, short duration green gram and cowpea are more remunerative than pearl millet when sown late.
DRY SPELL IMMEDIATELY AFTER SOWING
Dry spells are common in dryland agriculture. Due to dry spell after sowing of crop it might result in poor germination due to soil crusting, withering of seedlings and poor establishment of crop stand. The adverse effect of moisture stress should be mitigated to avoid total crop failure. It is necessary to maintain proper plant stand to ensure better yield. Therefore it is better to resow the crop than to continue with inadequate plant stand.
MID SEASON CORRECTION OR DRY SPELLS DURING CROP PERIOD
After sowing of crops and early growth any unexpected or unfavourable weather abnormality like long dry spell of 3 to 6 weeks, drought or early cessation of monsoon may occur. Unexpected or accidental occurrence of unfavourable weather after sowing is contingency and crop planning to overcome this contingency is called contingency crop planning. To mitigate the damaging effects of droughts after sowing of crop following mid season corrections are recommended:
1. Ratooning-The rate of soil moisture depletion increases with increasing leaf area. If drought occurs at 40- 50 DAS, reduction in leaf area either by rationing or thinning plant population can mitigate the adverse effects of drought. Sorghum and pearl millet responds to rationing. 2 % urea sprays after drought period is useful for indeterminate crops like castor, pigeon pea and groundnut.
2. Mulching-If the break in monsoon is very brief, soil mulching was found to be tool in extending the period of storage of water in the soil profile due to reduced heat load on the soil and hence the evaporation losses which in turn leads to extended periods of water availability. Repeated intercultivations in black soils results in formation of soil mulch on the surface. It acts as barrier to evaporation loss from soil profile. Deep cracks formed due to drought increases the loss of stored water by evaporation. Soil mulch minimizes deep cracking leading to reduced evaporation losses.
3. Thinning-If drought occurs during pre-flowering stage thinning is useful. Every third plant or alternate row may be removed to reduce the soil moisture loss and preserve it. Moisture stress of 35-50 days can be lessened by such thinning.
4. Weed Control-Weed control is very essential to save the crop from onslaught of drought as weeds rob soil moisture and nutrients as well.
5. Rain water harvesting and recycling-In situ water harvesting and / or runoff recycling are the potent measures for crop life saving during the periods of moisture stress. There is no control over the receipt of rainwater but it can be managed in a way better what is being done at present after it is received. Supplementary irrigation provided to the crop through rainwater harvesting and recycling particularly during the grain formation stage will be very much rewarding. Run-off recycling holds immense prospects in deep black soil where the seepage losses are very less. High intensity rains are quite common during the rainy season contributing 75% of seasonal rainfall. The inevitable runoff (10-40% of the total rainfall) could be stored in dugout ponds of appropriate sizes and recycled to the donor area, in the event of severe moisture stress.
6. Stripping of crop leaves- Generally, photosynthesis occurs in the upper 3-4 leaves. Hence excluding these leaves, lower leaves from the plant may be removed to reduce transpirational losses.
7. Intercropping and risk distribution-Application of meteorological information in terms of the frequency and probability of breaks in monsoon rains can be made to select a combination of crops of different durations in such a way that there is time lag in the occurrence of their grow for appropriate intercropping systems. The choice of intercrop depends upon the pattern of rainfall. There are 3 possibilities as:
1. Rainfall more uncertain in the early part of season.
2. Rainfall more uncertain in the later part of season.
3. Rainfall more or less uniformly distributed (in other words, the risk is uniformly distributed).
Region System
Hisar Pearlmillet + Cowpea
Agra Pearlmillet+ greengram
Banglore Pigeonpea + Cowpea
Hyderabad Sorghum + pigeonpea
Akola Sorghum + greengram
EARLY WITHDRAWAL OF MONSOON
Early withdrawal of monsoon before rabi seeding leads to problem of crop stand establishment and terminal drought. Therefore, rabi seeding should be as far as possible in early September to avoid the above two problems. All the suggested measures to mitigate the adverse effect of prolonged dry spells during crop period are necessary to overcome the soil moisture stress during the early withdrawal of monsoon.
EXTENDED MONSOON
Extended monsoon is seldom a problem in dryland agriculture. It benefits long duration kharif crops taken as a component crops in intercropping system and is also advantageous for rabi crops.
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References:
1-Principles & Practices of Dryland Agriculture- K. Govindan & V. Thirumurugan
2-Dryland Agriculture- S.C. Panda
3-Sustainable Development of Dryland Agriculture in India- Editor R.P. Singh
4-Principles of Agronomy-S.R. Reddy
5-Handbook of Agriculture- ICAR publications
Determinate And Indeterminate tomato
What is the difference between "determinate" and "indeterminate" tomatoes?
Determinate varieties of tomatoes, also called "bush" tomatoes, are varieties that are bred to grow to a compact height (approx. 4 feet).
They stop growing when fruit sets on the terminal or top bud, ripen their entire crop at or near the same time (usually over a 2 week period), and then die. Once this first flush of fruit has ripened, the plant will begin to diminish in vigor and will set little to no new fruit.
Determinate tomato varieties are often referred to as “bush” tomatoes, because they do not continue growing in size throughout the growing season. They are generally smaller than indeterminate tomatoes, with most growing to a compact 4-5 feet.
They may require a limited amount of caging and/or staking for support, should NOT be pruned or "suckered" as it severely reduces the crop, and will perform relatively well in a container (minimum size of 5-6 gallon).
Indeterminate varieties of tomatoes are also called "vining" tomatoes. They will grow and produce fruit until killed by frost and can reach heights of up to 10 feet although 6 feet is considered the norm. They will bloom, set new fruit and ripen fruit all at the same time throughout the growing season.
They require substantial caging and/or staking for support and pruning and the removal of suckers is practiced by many but is not mandatory. The need for it and advisability of doing it varies from region to region.. Because of the need for substantial support and the size of the plants, indeterminate varieties are not usually recommended as container plants.
Determinate varieties of tomatoes, also called "bush" tomatoes, are varieties that are bred to grow to a compact height (approx. 4 feet).
They stop growing when fruit sets on the terminal or top bud, ripen their entire crop at or near the same time (usually over a 2 week period), and then die. Once this first flush of fruit has ripened, the plant will begin to diminish in vigor and will set little to no new fruit.
Determinate tomato varieties are often referred to as “bush” tomatoes, because they do not continue growing in size throughout the growing season. They are generally smaller than indeterminate tomatoes, with most growing to a compact 4-5 feet.
They may require a limited amount of caging and/or staking for support, should NOT be pruned or "suckered" as it severely reduces the crop, and will perform relatively well in a container (minimum size of 5-6 gallon).
Indeterminate varieties of tomatoes are also called "vining" tomatoes. They will grow and produce fruit until killed by frost and can reach heights of up to 10 feet although 6 feet is considered the norm. They will bloom, set new fruit and ripen fruit all at the same time throughout the growing season.
They require substantial caging and/or staking for support and pruning and the removal of suckers is practiced by many but is not mandatory. The need for it and advisability of doing it varies from region to region.. Because of the need for substantial support and the size of the plants, indeterminate varieties are not usually recommended as container plants.
Importance of Vegetable production
Importance of Vegetable Production
1. Importance in human nutrition
2. Vegetables are important source of farm income
3. Vegetables have aesthetic value
4. Vegetables production for medicinal purpose
5. Roll of vegetables in national economy
6. Flexibility in production programme-unlike the fruits with vegetables the production programme can be adjusted and changed for better profits according to needs. With fruits it is difficult time taking and also expensive to change the production programme if it turns out to be unprofitable.
7. More yield per unit area-vegetables give higher total yield per unit area per unit time than cereals and other crops. The following table compares the yield per hectare of various crops:
Crops Average total yield per hectare in quintals
Wheat 20-25
Rice 25-30
Cauliflower 125-175
Watermelon 200-225
8. More net return per unit area
Crops Net return per hectare
Wheat 1000-1200
Rice 1000-1500
Cauliflower 1600-2200
Chillies 2500-3000
1. Importance in human nutrition
2. Vegetables are important source of farm income
3. Vegetables have aesthetic value
4. Vegetables production for medicinal purpose
5. Roll of vegetables in national economy
6. Flexibility in production programme-unlike the fruits with vegetables the production programme can be adjusted and changed for better profits according to needs. With fruits it is difficult time taking and also expensive to change the production programme if it turns out to be unprofitable.
7. More yield per unit area-vegetables give higher total yield per unit area per unit time than cereals and other crops. The following table compares the yield per hectare of various crops:
Crops Average total yield per hectare in quintals
Wheat 20-25
Rice 25-30
Cauliflower 125-175
Watermelon 200-225
8. More net return per unit area
Crops Net return per hectare
Wheat 1000-1200
Rice 1000-1500
Cauliflower 1600-2200
Chillies 2500-3000
Turmeric Processing Technology
Turmeric processing technology-Botanical name of turmeric is curcutha longa L. It is an important spice which is used for yellow colour and special flavour. Rhizomes of turmeric are often found in violet yellow colour. Central rhizomes are like tubers and small rhizomes like fingers coming out from the central one. It contains 1.8 to 5.4% curcumin due to this it has yellow colour. Some amount of starch and 2.5 to 7.2% oil is also obtained. It is used in the form of spices for colouration and flavour. In this very form it is used in medicine and cosmetic goods manufacturing. There are two types of turmeric produced in central India. One has solid and dark colour and the other long, soft and light colour.
Washing-At first rhizomes are separated after digging out from the soil and these are washed, so that particles of soil, spray residues and unuseful particles attached with the rhizomes are removed. For this rhizomes are kept soaked in water throughout the night. Later on rhizomes are taken out and water is sprayed. This process can be achieved by soaking and spraying equipment. Spraying is done at low pressure and wide angle jet. At the time of washing rhizomes are divided in two parts. First part from middle is called mother rhizomes. The second part of it which is long and thin is called Doctor Rhizome. Mother rhizome is kept for seed while Daughter rhizomes are further processed and sold.
Boiling/Blanching/Cooking:-The next step of processing is boiling or blanching. Traditionally boiling is done in metal or mud pots alongwith ¾ water. Top of the pots are covered with a lid or dry leaves. Boiling process is continued till foams and white foams start coming out. These come out with a special quality of flavour. Rhizomes are tested by pressing with fingers. If rhizomes are soft and inner colour has become yellow instead of red then this process is said to be complete.
By using developed method of boiling or blanching both colour and quality are improved. Time taken is less. In the developed method bulbs are treated with 0.1% Soda (Sodium Carbonate, Sodium bicarbonate or Ammonium Carbonate) and water solution. The time required for this process is 30 minutes to 6 hours. Boiler is used in the developed method which is metal kettle open from the top. Soda solution is filled in it and it is heated from the bottom by electric heater or fuel oil. Perforated frame loaded with turmeric tubers or bulbs are sunk here. Water from all sides of perforations enters inside making turmeric tubers soft. After 30 or 40 minutes bulbs/tubers are taken up and tested alongwith the frame. Cooking at the optimal level is important as overcooking spoils the colour and undercooking renders the product brittle resulting in breakage of rhizomes during drying and polishing. Once the water in the vessel starts boiling it may take 45-60 minutes to complete the cooking. Cooking at optimal level is indicated by the frothing of the liquid and the release of the characteristic turmeric aroma.
Drying -Cooked rhizomes are cooled first and spread slowly in the yard for drying. It takes at least 10 to 15 days for drying in the sun. Tubers are brought up and down in the middle of drying so that all are dried well. Mother rhizome takes comparatively more time while Doctor rhizome dries up quickly. Therefore these are dried separately also. After drying these become hard and solid. Completely dried turmeric holds 6% moisture content.
Polishing-Dried rhizomes are rubbed against ground or below the foot to take out the hard layer over them and small roots are removed. By this process colour of turmeric becomes bright or shining. Later on removed roots, light garbage and thin layerings are cleaned.
Machine is also used for polishing. For this a drum having 0.9m diameter and 0.6m length is used. It is kept horizontally on a shaft and operated by a handle. Average capacity of this machine comes to 32kg per batch. Dry turmeric 32kg approx.is filled and polishing is done at least for 7 minutes. During this period water is also sprinkled which causes improvement in the colour of turmeric.
Manual polishing consists of rubbing the dried turmeric fingers on a hard surface or trampling them under feet wrapped in gunny bags. The improved method is by using hand operated barrel or drum mounted on a central axis, the sides of which are made by expanded metal mesh. When the drum filled with turmeric is rotated, polishing is effected by abrasion of the 3 surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum. The turmeric is also polished in power operated drums.
Colouring-Exporting turmeric is given special colour by mixing yellow so that powder and processed materials can give better look and quality. Cleaning is done by two methods. One is dry colouring and the other wet colouring. In the first process dry powder of yellow colour is sprayed on boiled turmeric and rightly mixed. Powder is known as middle crome. In the wet colouring process its solution is prepared in water which is sprayed on rhizomes and mechanically mixed. After colouring is complete for one week these are dried. Later on these rhizomes are kept in sacks and closed for exporting (Adulteration-Lead chromate is sometimes used to produce a better finish. This should be actively discouraged.)
Grinding or Powder making-Traditionally dried and polished turmeric are cut into pieces and beaten in mortar and pestle. After this is milled or ground with hand operated chakki. Hammer mill is also used for grinding. Powder should be so fine that it passes through 300 micron sieve and nothing is left over the sieve.
Processing of turmeric by traditional method-In India, at various places different methods and equipments are used, but basic method is mentioned below in a process flow sheet.
Turmeric rhizomes
Washing
Boiling/Blanching/Cooking
Drying
Colouring
Grinding/Powdering
Sieving
Packaging
Marketing
Washing-At first rhizomes are separated after digging out from the soil and these are washed, so that particles of soil, spray residues and unuseful particles attached with the rhizomes are removed. For this rhizomes are kept soaked in water throughout the night. Later on rhizomes are taken out and water is sprayed. This process can be achieved by soaking and spraying equipment. Spraying is done at low pressure and wide angle jet. At the time of washing rhizomes are divided in two parts. First part from middle is called mother rhizomes. The second part of it which is long and thin is called Doctor Rhizome. Mother rhizome is kept for seed while Daughter rhizomes are further processed and sold.
Boiling/Blanching/Cooking:-The next step of processing is boiling or blanching. Traditionally boiling is done in metal or mud pots alongwith ¾ water. Top of the pots are covered with a lid or dry leaves. Boiling process is continued till foams and white foams start coming out. These come out with a special quality of flavour. Rhizomes are tested by pressing with fingers. If rhizomes are soft and inner colour has become yellow instead of red then this process is said to be complete.
By using developed method of boiling or blanching both colour and quality are improved. Time taken is less. In the developed method bulbs are treated with 0.1% Soda (Sodium Carbonate, Sodium bicarbonate or Ammonium Carbonate) and water solution. The time required for this process is 30 minutes to 6 hours. Boiler is used in the developed method which is metal kettle open from the top. Soda solution is filled in it and it is heated from the bottom by electric heater or fuel oil. Perforated frame loaded with turmeric tubers or bulbs are sunk here. Water from all sides of perforations enters inside making turmeric tubers soft. After 30 or 40 minutes bulbs/tubers are taken up and tested alongwith the frame. Cooking at the optimal level is important as overcooking spoils the colour and undercooking renders the product brittle resulting in breakage of rhizomes during drying and polishing. Once the water in the vessel starts boiling it may take 45-60 minutes to complete the cooking. Cooking at optimal level is indicated by the frothing of the liquid and the release of the characteristic turmeric aroma.
Drying -Cooked rhizomes are cooled first and spread slowly in the yard for drying. It takes at least 10 to 15 days for drying in the sun. Tubers are brought up and down in the middle of drying so that all are dried well. Mother rhizome takes comparatively more time while Doctor rhizome dries up quickly. Therefore these are dried separately also. After drying these become hard and solid. Completely dried turmeric holds 6% moisture content.
Polishing-Dried rhizomes are rubbed against ground or below the foot to take out the hard layer over them and small roots are removed. By this process colour of turmeric becomes bright or shining. Later on removed roots, light garbage and thin layerings are cleaned.
Machine is also used for polishing. For this a drum having 0.9m diameter and 0.6m length is used. It is kept horizontally on a shaft and operated by a handle. Average capacity of this machine comes to 32kg per batch. Dry turmeric 32kg approx.is filled and polishing is done at least for 7 minutes. During this period water is also sprinkled which causes improvement in the colour of turmeric.
Manual polishing consists of rubbing the dried turmeric fingers on a hard surface or trampling them under feet wrapped in gunny bags. The improved method is by using hand operated barrel or drum mounted on a central axis, the sides of which are made by expanded metal mesh. When the drum filled with turmeric is rotated, polishing is effected by abrasion of the 3 surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum. The turmeric is also polished in power operated drums.
Colouring-Exporting turmeric is given special colour by mixing yellow so that powder and processed materials can give better look and quality. Cleaning is done by two methods. One is dry colouring and the other wet colouring. In the first process dry powder of yellow colour is sprayed on boiled turmeric and rightly mixed. Powder is known as middle crome. In the wet colouring process its solution is prepared in water which is sprayed on rhizomes and mechanically mixed. After colouring is complete for one week these are dried. Later on these rhizomes are kept in sacks and closed for exporting (Adulteration-Lead chromate is sometimes used to produce a better finish. This should be actively discouraged.)
Grinding or Powder making-Traditionally dried and polished turmeric are cut into pieces and beaten in mortar and pestle. After this is milled or ground with hand operated chakki. Hammer mill is also used for grinding. Powder should be so fine that it passes through 300 micron sieve and nothing is left over the sieve.
Processing of turmeric by traditional method-In India, at various places different methods and equipments are used, but basic method is mentioned below in a process flow sheet.
Turmeric rhizomes
Washing
Boiling/Blanching/Cooking
Drying
Colouring
Grinding/Powdering
Sieving
Packaging
Marketing
Ginger Processing
Forms of ginger- Ginger is usually available in three different forms:
• Fresh (green) root ginger
• Preserved ginger in brine or syrup
• Dried ginger spice.
Fresh ginger is usually consumed in the area where it is produced, although it is possible to transport fresh roots internationally. Both mature and immature rhizomes are consumed as a fresh vegetable.
Preserved ginger is only made from immature rhizomes. Most preserved ginger is exported. Hong Kong, China and Australia are the major producers of preserved ginger and dominate the world market.
Making preserved ginger is not simple as it requires a great deal of care and attention to quality. Only the youngest tenderest stems of ginger should be used. It is difficult to compete with the well established Chinese and Australian producers; therefore processors are advised against making this product.
Dried ginger spice is produced from the mature rhizome. As the rhizome matures the flavour and aroma become much stronger. Dried ginger is exported, usually in large pieces which are ground into a spice in the country of destination. Dried ginger can be ground and used directly as a spice and also for the extraction of ginger oil and ginger oleoresin.
This brief outlines the important steps that should be taken pre-harvest and post-harvest to produce dried ginger.
Processing dried ginger-There are two important factors to consider when selecting ginger rhizomes for processing:
a. Stage of maturity at harvest. Ginger rhizomes can be harvested from about 5 months after planting. At this stage they are immature. The roots are tender with a mild flavour and are suitable for fresh consumption or for processing into preserved ginger. After 7 months the rhizomes will become less tender and the flavour will be too strong to use them fresh. They are then only useful for drying. Mature rhizomes for drying are harvested between 8 and 9 months of age when they have a high aroma and flavour. If they are harvested later than this the fibre content will be too high.
b. Native properties of the type grown. Gingers grown in different parts of the world can differ in their native properties such as flavour, aroma and colour and this affects their suitability for processing. This is most important when preparing dried ginger, which needs rhizomes with a strong flavour and aroma. Himachel, Maran, Mananthody and Kuruppampady are good varieties for the preparation of dried ginger. Size of rhizome is an important factor to consider when drying ginger – medium sized rhizomes are the most suitable for drying. Large rhizomes often have a high moisture content which causes problems with drying.
Making dried ginger-Dried ginger is available in a number of different forms – the rhizomes can be left whole or they may be split or sliced into smaller pieces to accelerate drying. Sometimes the rhizomes are killed by peeling or boiling them for 10 to 15 minutes, which causes the rhizomes to become blackened. They have to be whitened (bleached) by treating with lime or sulphurous acid. The only product which is acceptable for the UK market is cleanly peeled dried ginger.
The process for dried ginger:
• The fresh rhizome is harvested at between 8 to 9 months of age.
• The roots and leaves are removed and the rhizomes are washed.
• The rhizomes have to be ‘killed’ or inactivated. This is done by peeling, rough scraping or chopping the rhizome into slices (either lengthwise or across the rhizome). The skin should be peeled off using a wooden scraper made from bamboo to prevent staining the rhizome. Whole unpeeled rhizomes can be killed by boiling in water for 10 minutes.
• After peeling and washing, the rhizomes are soaked for 2-3 hours in clean water then soaked in a solution of 1.5-2.0% lime (calcium oxide) for 6 hours. This produces a lighter coloured (bleached) rhizome. After soaking, the rhizomes are drained.
• The rhizomes are dried. The traditional method is to lay the pieces on clean bamboo mats or on a concrete floor and sun-dry until a final moisture content of 10%. Drying may take anything from 7 to 14 days depending upon the weather conditions. During drying, the rhizomes lose between 60 and 70% in weight.
• In rainy conditions, a mechanical drier such as a tray drier should be used to accelerate the drying process. Sliced ginger pieces take only 5-6 hours to dry when a hot air drier is used. Whole peeled ginger rhizomes take about 16-18 hours to dry in a mechanical drier. It is important to monitor the air flow and temperature during drying. The drying temperature should not exceed 60°C as this causes the rhizome flesh to darken. See the Practical Action Technical Brief on drying for further information on the different types of drier available.
• After drying, the rhizomes are cleaned to remove any dirt, pieces of dried peel and insects. An air separator can be used for large quantities, but at the small scale it is probably not cost effective.
• The dried rhizomes should be packaged into air-tight, moisture proof packaging for storage or export.
• Fresh (green) root ginger
• Preserved ginger in brine or syrup
• Dried ginger spice.
Fresh ginger is usually consumed in the area where it is produced, although it is possible to transport fresh roots internationally. Both mature and immature rhizomes are consumed as a fresh vegetable.
Preserved ginger is only made from immature rhizomes. Most preserved ginger is exported. Hong Kong, China and Australia are the major producers of preserved ginger and dominate the world market.
Making preserved ginger is not simple as it requires a great deal of care and attention to quality. Only the youngest tenderest stems of ginger should be used. It is difficult to compete with the well established Chinese and Australian producers; therefore processors are advised against making this product.
Dried ginger spice is produced from the mature rhizome. As the rhizome matures the flavour and aroma become much stronger. Dried ginger is exported, usually in large pieces which are ground into a spice in the country of destination. Dried ginger can be ground and used directly as a spice and also for the extraction of ginger oil and ginger oleoresin.
This brief outlines the important steps that should be taken pre-harvest and post-harvest to produce dried ginger.
Processing dried ginger-There are two important factors to consider when selecting ginger rhizomes for processing:
a. Stage of maturity at harvest. Ginger rhizomes can be harvested from about 5 months after planting. At this stage they are immature. The roots are tender with a mild flavour and are suitable for fresh consumption or for processing into preserved ginger. After 7 months the rhizomes will become less tender and the flavour will be too strong to use them fresh. They are then only useful for drying. Mature rhizomes for drying are harvested between 8 and 9 months of age when they have a high aroma and flavour. If they are harvested later than this the fibre content will be too high.
b. Native properties of the type grown. Gingers grown in different parts of the world can differ in their native properties such as flavour, aroma and colour and this affects their suitability for processing. This is most important when preparing dried ginger, which needs rhizomes with a strong flavour and aroma. Himachel, Maran, Mananthody and Kuruppampady are good varieties for the preparation of dried ginger. Size of rhizome is an important factor to consider when drying ginger – medium sized rhizomes are the most suitable for drying. Large rhizomes often have a high moisture content which causes problems with drying.
Making dried ginger-Dried ginger is available in a number of different forms – the rhizomes can be left whole or they may be split or sliced into smaller pieces to accelerate drying. Sometimes the rhizomes are killed by peeling or boiling them for 10 to 15 minutes, which causes the rhizomes to become blackened. They have to be whitened (bleached) by treating with lime or sulphurous acid. The only product which is acceptable for the UK market is cleanly peeled dried ginger.
The process for dried ginger:
• The fresh rhizome is harvested at between 8 to 9 months of age.
• The roots and leaves are removed and the rhizomes are washed.
• The rhizomes have to be ‘killed’ or inactivated. This is done by peeling, rough scraping or chopping the rhizome into slices (either lengthwise or across the rhizome). The skin should be peeled off using a wooden scraper made from bamboo to prevent staining the rhizome. Whole unpeeled rhizomes can be killed by boiling in water for 10 minutes.
• After peeling and washing, the rhizomes are soaked for 2-3 hours in clean water then soaked in a solution of 1.5-2.0% lime (calcium oxide) for 6 hours. This produces a lighter coloured (bleached) rhizome. After soaking, the rhizomes are drained.
• The rhizomes are dried. The traditional method is to lay the pieces on clean bamboo mats or on a concrete floor and sun-dry until a final moisture content of 10%. Drying may take anything from 7 to 14 days depending upon the weather conditions. During drying, the rhizomes lose between 60 and 70% in weight.
• In rainy conditions, a mechanical drier such as a tray drier should be used to accelerate the drying process. Sliced ginger pieces take only 5-6 hours to dry when a hot air drier is used. Whole peeled ginger rhizomes take about 16-18 hours to dry in a mechanical drier. It is important to monitor the air flow and temperature during drying. The drying temperature should not exceed 60°C as this causes the rhizome flesh to darken. See the Practical Action Technical Brief on drying for further information on the different types of drier available.
• After drying, the rhizomes are cleaned to remove any dirt, pieces of dried peel and insects. An air separator can be used for large quantities, but at the small scale it is probably not cost effective.
• The dried rhizomes should be packaged into air-tight, moisture proof packaging for storage or export.
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