Celebrating rice

B Mishra and JS Bentur give an update on the crop and assess the recent management techniques and technologies that farmers can benefit from

Rice belongs to the grass family under genus Oryza and has two main cultigens, Sativa in Asia and Glaberrima in Africa. Aquatic rice species Zizania aquatica and Zizania palistris, are endemic to North America. Rice is a semi-aquatic crop and can be grown in different environments ranging from rainfed uplands at an altitude of 3,000 m to rainfed lowlands, irrigated lands, tidal swamps and deep-water areas.
Rice is one of the most important crops of India and the country ranks second in its production (93.08 million tonnes) and export. Since independence the rice production trend has kept in pace with the population growth trend (Figure 1).
The export of rice from India grew to 4.5 million tonnes in 2002. In 2002-03, rice production dropped by 22 per cent due to drought conditions.
Keeping in view, the average annual population growth rate of 1.51 per cent and the per capita consumption estimate of about 250 g of rice per day, demand for rice is expected to be 100-105 million tonnes in 2010 and 130-140 million tonnes by 2025. Thus there is a need to increase rice production by 1.5 million tonnes every year.

CROP MANAGEMENT
Progress in breeding rice varieties with genetic potential and research on crop husbandry, has resulted in development of several production technologies that have made a significant contribution to the enhancement of yield and input-use efficiency in rice.
Recent research has proven that rice can be cultivated by row sowing of germinated seed using a row seeder. This process reduces labour cost involved in transplanting. However, weeds need to be carefully managed using weeders or weedicides.
Currently, water saving technology in rice production is the priority area of research. Simple crop management steps can save water without reducing the grain yields significantly.
Recent popularity of the System of Rice Intensification cultivation claims rice yields of 6-8 tonnes as against 4-5 tonnes with normal practice. Integrated crop management is yet another alternative.

PEST MANAGEMENT
Rice is essentially a crop of warm humid environment, which is conducive to the survival and proliferation of insects and disease causing micro-organisms. Newly emerging threats to the crop include leaf folder, rice hispa, gundhi bug, earcutting caterpillar, leaf and panicle mites. Loss in grain yield due to these insect pests is estimated to vary from 10-15 per cent. Sheath rot, brown spot and false smut are some of the newly emerging diseases that take a toll of about 10 per cent of the grain yield.
Host plant resistance has played an important role in mitigating key pest problems. A large number of pest resistant rice varieties have been developed. However, insect pests and pathogens also display a wide range of genetic variability resulting in development of new virulent races and biotypes that overcome the plant resistance.
Continuing efforts have enabled development of biotype / race specific resistant varieties.
Extensive studies have identified new generation of chemicals that are less toxic, effective in very low doses and are specific to pests while being relatively safe to other useful organisms.
Several plant products such as various formulations of neem, are found to be effective in checking pests and do not adversely affect the environment.
Biological control agents like predators, parasites and pathogens check the growth of insect pests and pathogens. Avoiding pesticide application at the time of abundance of these natural enemies, avoiding broad-spectrum insecticides, adopting selective methods of insecticide application like seed soaking and seedling root soaking are some of the methods to reduce excessive use of pesticides. Artificial release of egg parasitoids like Trichogramma have been found effective against pests like leaf folder and stem borer, while biological control of diseases such as sheath blight through use of strains of bacteria is feasible. Among the new eco-friendly approaches, the use of pheromones for management of the yellow stem borer is effective.
Great emphasis is laid on development and practice of location specific and situation specific Integrated Pest Management (IPM). Normally, IPM package involves cultivation of a resistant or tolerant variety against the key pests like gall midge, brown plant hopper or stem borer, coupled with need-based application of effective insecticides against other pests as decided by regular surveillance. In case of fungal diseases like timely intervention with effective chemicals is suggested when resistant varieties are not available.

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