Sustainable agriculture

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Increased food production in India was made possible by the
employment of modern technology in agriculture. The increase in the
productivity is mainly due to rapid rise in overall area under cultivation of cereals.

To maintain the crops and productivity, we have to expand
irrigation facilities and use large amounts of fertilizers and pesticides.
This overexploitation had resulted in the degradation of soils and their erosion.

Due to degeneration in soil fertility, the traditional varieties of
crop plants as cultivated in earlier periods got disappeared or are on the brink of extinction.

Our agriculture is slowly being converted into an unsustainable system in the years to come, as the cost of chemicals and fertilizers, labour, cost of seeds are going to make the agricultural products costlier.

This will affect millions of uneducated farmers.

Hence, to remedy this situation, we will have to find alternative permanent arrangements in sustainable agriculture.

To protect the interest of the farmers on their agricultural lands and
capital investments, sustainable agriculture which is the best source of
alternative method should be compulsorily taken up and practiced by the traditional farmers.

Sustainable agriculture can be carried on without any threat to our soils, environment, plants and animal communities.

Excessive drainage of our energy and material resources can be considerably saved and protected when sustainable agriculture is intensively taken up by the farmers and practiced. This can be achieved by

1. Maintaining a healthy soil community which can automatically
regenerate soil fertility by providing organic manures, increasing fallow
periods, avoiding excessive use of chemical fertilizers and pesticides.

2. Infusing bio-diversity in agriculture by sowing mixed crops, crop
rotation etc.

3. The use of alternative food sources which may reduce
overdependence to certain crops.

Men are exploiting only few species of crop plants as food and cultivate only about 15 species of plants as food crops to feed 90 per cent of the world’s population.

There are thousands of species of plants with useful and edible parts which can serve as a food source for the mankind.

This will widen our resource base on food crops and add sustainability to supplies by reducing the dependence on a few species.

eg. Winged bean which has high protein and oil.

Leaves of Ilex paraguriensis, which can be a substitute for tea and powdered seeds of Cola nitida instead of coffee.

Farmers should practice ‘organic farming’ so that it will not disturb
the ecosystem of the cultivable area and leads to sustainable yields at low costs, both to the farmer and to nature.

Chemicals, minerals, pesticides and insecticides are now categorised under non-renewable resource materials. Therefore, in the long-term strategy, these materials will make farming non-sustainable and non-productive.

Shifting to original and excessive use of organic manure, rotation of leguminous or nitrogen fixing crops, use of VAM fungi, transgenic crop and application of biofertilizer are being encouraged and practiced.

Sustainable agriculture includes scientific methods of farming that
utilise renewable resources, increase in yield, avoidance of manmade
complex substances known as Xenobiotics which are used as insecticides and pesticides that cause pollution to soil and environment.

Plant tissue culture and biotechnology also play a major role in this.

50 varieties of rice and 20 varieties in wheat have been developed in China by using these new techniques without damaging the environment.

New disease resistant virus free plants and stress resistant plants, are successfully produced. Similarly, transfer of nif (nitrogen fixing) gene to nonleguminous crops will improve higher yield.

Biotechnology and tissue culture contributed more to sustainable agriculture by providing biofertilizer, biopesticides, disease and insect resistant varieties through creation of transgenic crops, single cell protein, production of valuable pharmaceutical products and herbal drugs (Ginseng Vinca, Emetine from Cephalis) by using micropropagation technique.

To conclude Sustainable agriculture is an eco-friendly farming system
associated with production of food while maintaining on biophysical
resources including soil, water, biota with no adverse impacts on the
environment.

So it should

1. maintain or improve the production of clean food.

2. maintain or improve the quality of landscape which includes soil,
water, biota and aesthetics

3. have minimal impact on the environment.

4. be economically viable and

5. be acceptable to society.

Sustainable farming uses ecofriendly fertilizers, and pesticides and
modern technologies, such as improved seed, modern equipments for lowtillage practices, pest control using biological control principles and weed control that depends on crop rotations.

Sustainable farms try to use wind or solar energy instead of purchased energy and use organic manure and nitrogen fixing legumes as green manures to maintain soil fertility thereby reducing supply from outside farms.

The emphasis is on maintaining the environment without causing any pollution.

Organic farming is defined as production systems which avoids the
use of synthetic fertilizers, pesticides, growth regulators and livestock feed additives.

It depends upon crop rotation, crop residues, animal manures,
legumes, green manures, off-farm organic wastes using mechanical
cultivation, biological pest control (biopesticides) to maintain soil
productivity and to supply plant nutrients and to control insects, weeds and pests.

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Other links 

Plant physiology – photosynthesis and its significance

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BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Biopiracy

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Countries like America, Japan, United Kingdom, France and Germany
are industrialised nations. These nations are advanced in technology with financial resources but compared with the Indian sub-continent are poor in bio diversity and traditional knowledge related to utilisation of flora and fauna that constitute the bio resources.

The clandestine exploitation and utilisation of bio resources from a country by several organisations and multinational companies without proper authorisation is known as Biopiracy.

Although the developing nations are not so financially sound,
they are however rich in traditional knowledge and bio diversity.

For a very long period, the tribal people in the remote areas of jungles
as also the people of rural areas have been using certain important herbal plants for treating certain diseases.

Since, the habitations of the tribal people are surrounded by a variety of plants and animals, they have acquired a sound knowledge of their uses particularly of their medicinal values.

This knowledge can be exploited to develop commercially important drugs from the plants. Traditional knowledge has greater utility value as it saves time, effort and expenditure for their commercialisation.

Multinational companies of the rich nations are collecting and exploiting the bio resources without any authorization in the following ways:

1. Plants like Catharanthus roseus (Vinca rosea) are exported to
countries as medicinal plants since they possess anticancerous properties.

The companies of the rich nations are interested in the bio molecules present in the plant. These compounds produced by living organisms are patented and used for commercial activities.

As a result of this, the farmers who cultivate the crop are being deprived of their rightful claims and compensations.

2. The genetic resources of the developing nations are over exploited
by the rich nations. For instance, Basmati rice is a crop grown indigenously in India from a very long time.

In U.S.A the Government had granted a patent to cover the entire ‘basmati’ rice plant so that other countries or institutions cannot undertake any other research programmes pertaining to Basmati plant.

In U.S.A, such patents are given for 17 long years.

3. Pentadiplandra brazzeana, a native plant of West Africa, produces
a protein called brazzein. It is several 100 times as sweet as sugar. Local people use it as a low-calorie sweetener.

This development could have serious implications for sugar exporting countries. Richer nations are over exploiting the commercial resources of the developing countries without adequate compensation.

With advances in scientific equipments, instruments and techniques, the bio diversity of the poor and developing nations of the tropics are overused and exploited by the rich nations.

There is a growing awareness of this over exploitation and hence the developing countries are enacting legislative laws to prevent this over exploitation by the rich nations.

Bio patent

The emergence of modern bio technology has brought forth many legal
characterizations and treatment of trade related bio technological processes and produces, popularly described as Intellectual Property. Intellectual Property Protection (IPP) and Intellectual Property Rights (IPR) are the two unique facets of any Bio patency.

Intellectual property includes ‘patents’, ‘trade secrets’, ‘copy rights’ and ‘trade marks’ obtained for processes and products created through one’s own knowledge and research.

The right to protect this property prohibits others from making copying
using or selling these processes and products. In this era of bio technology, one of the most important examples of intellectual property is the creation of organisms containing new recombinant DNA.

Another example of Intellectual property is the new crop varieties, which are protected through ‘Plant Breeder’s Rights’ or PBR’s. The plant breeder who developed this new variety enjoys the exclusive right for marketing the variety.

Patenting of important crops and animal breeds may bring down a
shortfall in genetic resources. One of the major negative aspects of bio patency is that it may lead to scarcity of genetic resources. In addition,
majority of the people may not have access to certain rare genetic resources protected by Bio patency laws.

People argue that giving patent rights to transgenic plants and
transgenic animals is a wrongful idea as these patents will work as
impediments in free exchange of genetic materials for improvement of
crops and livestock.

Intellectual Property Rights may also adversely affect the following:
Food security, use of evolved agricultural practices, bio logical
diversity and ecological balance and livelihood of the poor in developing countries.

Patents

The Indian Patent Act of 1970 allows process patents, but no product
patents for foods, chemicals drugs and pharmaceuticals. Duration of patent in India is 5 years.

Under USA law, a patent means grant of “right to exclude others from making, using or selling” an invention for a 17 year period. To day, many favour the patenting of inventions arising from basic research.

Patents are granted as per the law of the State and are also
disputed in the court of Law whenever complaints of infringement of the patents are violated by the people.

In 1980, the discovery of an oil eating bacterium (Pseudomonas) by a non-resident Indian Scientist (Dr. Chakrabarty) was patented in USA by a multinational Corporation. Similarly, an ‘oncomouse’ was also patented.

All this means that life forms could be patented.

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Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Bio – war

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Nowadays, microbes are misused as biological weapons. For instance, a single gram of the most virulent strains of weaponized. Smallpox or anthrax could contain 250 million infectious doses.

Under ideal dispersal conditions, about half the people of the entire. World when exposed to these germs could become ill and one-third might die.

Deadly organisms

Even from a very long period, pathogens causing some of the deadliest diseases in men are being used as biological weapons. More than 2,000 years ago, Scythian archers used their arrow heads. Which were dipped in rotting corpses in order to cause panic amongst people.

The tips of arrowhead caused infections. During World war II, papar bags filled with plague infested fleas were employed as biological weapons to kill thousands of people. At that time, well equipped and expensive laboratories were established to mass produce biological weapons.

At present, each and every nation is facing the threat from biological weapons. People affected by the biological war have to suffer throughout their life.

Genetically Modified Organisms (GMO) in biological warfare

Using Molecular biology techniques, new combinations of genes were
attempted to create genetically modified organisms (GMO).

Some of the most lethal agents known to have been tested in biological warfare are anthrax, plague, smallpox and Ebola viruses with viral diseases.

People were aware of the reality that a small group of fanatical terrorists could easily contaminate the country’s air, water and food with lethal pathogens or biological toxins.

Biological warfare

Thus biological warfare introduces issues of pathogenicity, toxicity,
routes of exposure, safety measures and the movement, distribution and persistence of dangerous biological materials in our environment.

In biological warfare strategies, the genetically engineered microorganisms are made to spread into the enemy’s territorial environment, with unpredictable and perhaps catastrophic consequences.

The released dangerous microorganisms ‘upset the balance of nature’.

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Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Genetically modified food

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The greater concern in food biotechnology is the integration of both
modern biological knowledge and techniques and current bioengineering principles in food processing and preservation.

Modern biotechnological techniques will have considerable importance in influencing trends in the food market, namely cost, preservation, taste, consistency, colour and above all, health aspects.

Every year more than a million children die and another 3,50,000 go
blind from the effects of vitamin A deficiency. Employing genetic
engineering techniques, Potrykus of Switzerland and Peter Beyer of Germany transferred genes that make carotene in daffodils into Oryza sativa.

Ordinarytechniques of plant breeding do not offer a way to enrich the crop. Extracting carotene genes from daffodils, Potrykus and Beyer had introduced these genes into the soil bacterium.

Agrobacterium tumefaciens, the transgenic agrobacteria were then incubated with rice embryos in plant tissue culture medium. As the bacterium infects the rice cells, they also transfer the genes for making beta carotene.

A number of examples are available where transgenic plants suitable for food processing have been developed.
(i) Tomatoes with elevated sucrose and reduced starch could also be
produced using sucrose phosphate synthase gene.
(ii) Starch content in potatoes could be increased by 20 to 40 per cent by using a bacterial ADP glucose pyrophosphorylase gene (ADP GPPase).
(iii) Vaccines, antibodies and interferons can be consumed directly along with tomato, banana and cucumber.

Edible vaccine

Acute watery diarrhoea is caused by Escherichia coli and Vibrio
cholerae that colonize the small intestine and produce enterotoxin.
Attempts were made to produce transgenic potato tubers that they could still retain vaccines in their tubers, even after the tubers had become 5 per cent soft after boiling. 50 per cent of vaccine was still present in the tubers.

Edible antibodies

Transgenic plants are being looked upon as a source of antibodies.
They can also provide passive immunization by direct application.

Edible interferons

Interferons are the substances made of proteins and are anti-viral in
nature. Scientists have successfully produced transgenic tobacco and maize plants that secrete human interferons . Today, rice crops have been enriched with vitamin A through gene manipulation. Similarly, pulse crop have been tampered with to produce lysine-rich pulse seeds. Such genetically modified food (GMF) are now becoming components of human staple food.

It is hoped that one day genetically engineered plants will have one
or more of these attributes:
i. They will show tolerance against heat, cold, drought or salt.
ii. They are more nutritious.
iii. They can be stored and transported without fear of damage.
iv. They require less fertilizer.
v. They produce chemicals and drugs that are of interest to humans.

Back to botany topic list

Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Biocontrol of insect pests

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1. The manufacture of methyl isocynate (MIC) was started in 1980 in
India to make Serin (carbaryl), a powerful pesticide that can kill more
than 100 types of insects attacking 100 different crops.

2. Many of the chemical pesticides, which are used to control several
crop pests also affects the beneficial organisms.

3. They also bring about considerable damages to living organisms
because of their hazardous effects in the environment.

There was an enmasse killing of more than 4,000 people, many animals and plants, when methyl isocyanate (MIC) gas leaked out in the night of 2nd and 3rd December, 1984 from the underground reservoir of Union Carbide Factory at Bhopal.

This is mentioned as Bhopal Tragedy. Many of the people exposed to this poisonous gas are suffering even today.

4. Majority of microorganisms such as viruses, bacteria, fungi,
protozoa and mycoplasma are known to kill insect pests.

The suitable preparations of such microorganisms for control of insects are called as ‘microbial insecticides’. These are non-hazardous, non-phytotoxic and are selective in their action.

They are eco-friendly not responsible for environmental degradation. The most frequently used bio-control agent is Bacillus thuringiensis and Pyrethrum extracted from the inflorescence of Chrysanthemum belonging to Asteraceae.

Bacterial pesticides

B. thuringiensis is a widely distributed bacterium. It is a saprophytic bacterium and can be isolated from soils, litters and dead insects. It is a spore-forming bacterium and produces several toxins such as exotoxins and endotoxins in crystallized forms.

The bacterium is harmful to lepidoptera insects. After infection of spore, larvae are damaged due to the secretion of a single large crystal in the cell. This crystal (toxin) is proteinaceous in nature.

Back to botany topic list

Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Citrus canker

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Pathogen

Disease due to a bacterium Xanthomonas citri. This bacterium is of bacillus and gram negative type. In India, this is the most commonly prevalent disease during the rains.

Symptoms

The disease affects the leaves, twigs, thorns and fruits. All green
parts and maturing fruits become more or less covered with brown scabby spots surrounded by dark – brown glossy margins.

The lesions may enlarge to a diameter of 3 or 4 mm become raised and rough and turn brown. The bacteria enter through the stomata and wounds and multiply in the cortex to which they are confined.

Control

The infection can be largely prevented by removing the infected branches and spraying the plants with Bordeaux mixture or spraying 3 to 4 times in a season with antibiotic the streptocycline at the rate of 1 gm in 45 liters of water.

Tungro disease of rice

Pathogen

Disease incited by a virus Rice Tungro virus. The virus is transmitted by a leafhopper.

Symptoms

The symptoms appear first on the emerging leaf. They are mild
interveinal chlorosis (loss of chlorophyll), mild mottling and yellowing. Plant shows stunted growth and symptoms appear on the lower leaves. They turn yellow orange, bend downwards and possess dark brown spots.

Transmission of virus

The leafhopper retains infectivity for a short period only and transmits the virus to another plant immediately after feeding on an infected plant.

Biopesticides

Biological agents that are used for control of insects, weeds and
pathogens produced from living organisms are called biopesticides. Microorganisms such as viruses, bacteria, fungi, protozoa and mites may be used as biopesticides.

Back to botany topic list

Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Groundnut or peanut – Arachis hypogea

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Tikka disease of groundnut

Pathogen Disease incited by a fungus Cercospora personata.
Systematic position The fungus belongs to class Deuteromycetes.

Symptoms

Lesions appear on the leaves, when the plants are atleast two months old. The symptoms appear in July and continue upto maturity of the plant.

The lesions on the leaves are rounded and 1 to 6 mm in diameter. These spots are dark brown or black and found on both surfaces of the leaf. Yellow border develops around each such leaf spot.

Pathogen

The mycelium of Cercospora personata is brown, septate branched
and slender. Branched haustoria are produced to absorb food materials from the host tissue.

The conidia are long and septate. Each conidiophore produces single conidium at its tip. The spread of the disease takes place by means of conidia which are dispersed by wind.

Control

The disease can be controlled by sanitation and crop rotation. The
use of phosphatic and potassic manures reduce the disease. Sulphur dusting is quite effective. Resistant variety should be sown.

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Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Crop diseases and their control

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The diseases in crop plants result in a heavy loss of crop yields and
cause considerable damage to crops year after year. To check the plant diseases, it becomes necessary to know about the cause of the diseases, of the life history of the causal organism and of the meterological conditions which influence the host and parasite interaction.

Control measures may be divided into two main groups – prophylaxis
and disease resistance. Prophylaxis includes the protection of the host from exposure to the pathogen, from infection or from environmental factors favourable to disease development.

Disease – resistance implies the improvement of resistance of the host to infection and to disease development.

SPECIFIC DISEASES

Rice – Oryza sativa
Pathogen Disease incited by a fungus, Pyricularia oryzae.
Name of the disease Blast disease of rice.
Systematic position The fungus belongs to class: Deuteromycetes.

Symptoms

The symptoms are found on the leaf blades, leaf sheaths and rachis.
Characteristic isolated, bluish – green necrotic lesions with a water –
soaked appearance are formed on the leaf – blades.

The lesions are broad in the centre and possess narrow elongations on its top and bottom. The lesion – formation leads to ultimate drying of the leaves, and the seedlings wither and die.

After transplantation, the symptoms appear in the form of necrotic
lesions both on the leaf lamina and the leaf sheaths. The necrotic lesion is spindle shaped grey in the centre and remain surrounded by brown and yellowish zones. The leaves ultimately dry up.

The pathogen

The fungus Pyricularia oryzae when young possesses hyaline and
septate mycelium. On maturity, the colour of mycelium changes to olive brown. Conidia are produced terminally. Each conidium is obpyriform septate with a small basal appendage.

Control measures

The most economic method of control is the cultivation of resistant,
high yielding varieties.

Seed treatment

Immersion of the seeds in 0.2 per cent solution of Kalimat B for 24
hours controlled the disease and promoted the growth of seedlings. The seed protectants such as agrosan, cerasan and spergon have been proved responsible for the control of disease.

Sanitation

Plant debris should be collected and destroyed. The secondary host
plants such as Digitaria marginata should be collected from paddy fields and destroyed.

Spraying and dusting

Blast disease can be controlled effectively by spraying the fungicide,
Bordeaux mixture at least 4 times before and after flowering of the crop. Bordeaux mixture formula is as follows:
Copper sulphate 9 Kgs.
Quick lime 9 Kgs.
Water 250 litres.
The dusting of organomercuric compounds has been suggested for
controlling blast.

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Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Green manuring, Mycorrhiza as biofertilizer

---

Benefits from biofertilizers

 

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---

Benefits from biofertilizers

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1. Biofertilizers are easy to produce in abundance and are available
at low cost to the marginal farmers.

2. It increases soil fertility without causing any damage to the soil.

3. Application of biofertilizers increases yield upto 45 per cent and
the left over biofertilizers in the soil increases yield as long as the
biofertilizer remains in the soil up to 3 to 4 years.

4. Azolla, which is a biofertilizer amends the soil with organic matter.
Cyanobacteria in particular secrete growth promoting hormones
like indole 3-acetic acid, indole butyric acid, naphthalene acetic
acid, aminoacids, protein and vitamins to soil.

5. Cyanobacteria grow well both in acidic as well as in alkaline soils.
Since, cyanobacteria are potent neutralizers, they help in the
neutralization of soil. The process of converting untenable, fallow
land to cultivable soil is termed as soil reclamation. Blue green
algae play a vital role in this conversion.

6. Symbiotic nitrogen fixing Rhizobium is a biofertilizer. It adds 50
to 150 Kg of nitrogen to soil per hectare. Azatobacter and
Azospirillum secrete antibiotics which act as biopesticides.

7. Ectotrophic mycorrhiza, which acts as a biofertilizer, increases
the surface area of the roots of host plants, so that more absorption
of nutrients by the roots is made possible.

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Other links 

Plant physiology – photosynthesis and its significance

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BIOLOGY IN HUMAN WELFARE Introduction & Food production

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Aims of plant breeding

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Aspects of plant breeding and Types

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Hybridization in plant breeding

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Polyploid breeding, Mutation breeding, Breeding for disease resistance

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Genetic engineering, Improved varieties, Role of biofertilizers

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Green manuring, Mycorrhiza as biofertilizer

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Crop diseases and their control, Rice – Oryza sativa

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Groundnut or peanut – Arachis hypogea

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Citrus canker, Tungro disease of rice

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Biocontrol of insect pests Bacterial pesticides

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Genetically modified food

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Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

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Commonly Available Medicinal Plants

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Microbes in medicine

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Economic importance of Food plant Rice

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Oil plant Groundnut Economic importance

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Fibre plant – Cotton Economic importance

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Timber yielding plant Teak Economic importance

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Green manuring

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Various leguminous plants like Crotalaria juncea, Cassia mimusoides, Glycine max, Indigofera linifolia, Sesbania rostrata, Acacia nilotica, Leucena, Lathyrus and Mucuna are used as green manures.

They accumulate more than 80 Kg of nitrogen per hectare in the soil when grown as green manures. Azolla is an aquatic fern, which contains an endophytic cyanobacterium Anabaena azollae in its leaves.

It is used as a biofertilizer in rice field. Out of six species of Azolla, A. pinnata is widely employed as a successful biofertilizer in Indian rice fields. It adds 30 Kg of nitrogen per hectare where the yield is equivalent to that of urea or ammonium phosphate.

Mycorrhiza as biofertilizer

Mycorrhiza is a root inhabiting fungus found around or inside the
roots of many plants. It increases growth and yield and also provides protection to the roots against edaphic (soil) stresses, pathogen and pests.

Helps in the increased uptake of soil and mineral water solution by the plant root system. It provides many uses for the host plants eg. VAM (Vesicular Arbuscular Mycorrhiza) fungi. Mycorrhiza is of two types.

a. Ectotrophic mycorrhiza, which are found only outside the surface
of roots of plants. eg. Basidiomycetous fungi.

b. Endotrophic mycorrhiza, which are found inside the roots, in the
intercellular spaces and even inside the cell (intra and intercellular)
eg. VAM fungi.

Back to botany topic list

Other links 

Plant physiology – photosynthesis and its significance

---

BIOLOGY IN HUMAN WELFARE Introduction & Food production

---

Aims of plant breeding

---

Aspects of plant breeding and Types

---

Hybridization in plant breeding

---

Polyploid breeding, Mutation breeding, Breeding for disease resistance

---

Genetic engineering, Improved varieties, Role of biofertilizers

---

Benefits from biofertilizers

---

Crop diseases and their control, Rice – Oryza sativa

---

Groundnut or peanut – Arachis hypogea

---

Citrus canker, Tungro disease of rice

---

Biocontrol of insect pests Bacterial pesticides

---

Genetically modified food

---

Bio war, Genetically Modified Organisms (GMO) in biological warfare

---

Biopiracy, Bioresources, Biomolecules, Biopatent, Biotechnology

---

Sustainable agriculture

---

Medicinal plants including microbes

---

Commonly Available Medicinal Plants

---

Microbes in medicine

---

Economic importance of Food plant Rice

---

Oil plant Groundnut Economic importance

---

Fibre plant – Cotton Economic importance

---

Timber yielding plant Teak Economic importance

---