Rice is grown here on an area of over 2.5 million hectares with an average yield of 2,117kg per hectare. The country ranks 9th with respect to area and 14th for yield per hectare in the world. There is 50.42 per cent gap between the actual and potential yield. The reason for this gap in yield is the poor rice production practices adopted by farmers and rice-growers of the area.
Rice ratooning is one of the potential and attractive alternative technologies to increase rice production. Based on land and water management, rice ecosystem is mainly divided into lowland, upland and deep water or floating rice. Rice ratooning is mainly practiced on lowland rice ecosystem.
Rice ratooning is not a new practice with farmers. It has been successfully adopted in many countries including India, Japan, USA, Philippines Brazil, Thailand and Taiwan. In India, of the 40mha under rice, about 18.9mha constitute the ratooning under lowland.
Rice ratooning can be practised as an alternative to double cropping in areas of available water after the main crop season, particularly it is suited to hilly, tropical areas with heavy rainfall and under rain-fed conditions to tide over moisture stress because no other crops except rice can be grown under the climate and moisture limitations.
Advantages: The main advantage of rice ratooning is that in areas where rice is the main crop, double crop of rice can be grown for additional returns. The ratoon crop matures earlier, it has been reported that days to maturity of the ratoon crops are 65 per cent less than the main crop. It requires 50 to 60 per cent less labour. Require less water inputs, water use efficiency is high and crop uses 60 per cent less water than the main crop. The production cost is lower due savings in land preparation, transplanting or direct seeding and crop maintenance during early growth. This system requires short duration, creating possibility for growing another crop in the same cropping year and offers an opportunity to increase cropping intensity per unit of cultivated areas. The yield is up to 50 per cent of the main crop. Rice varieties differ in their ratooning ability. In case of Ratoon crops from early maturing varieties, better performance in temperate is reported.
However, intermediate to late maturing cultivars are required for raising a good crop. The general trend is that intermediate to late maturing varieties produce higher yields than early maturing varieties. Hence, there are no set rules with regard to choice of cultivar regarding ratooning. Good agronomist of the area can be a good ratooner. Many factors like variation in soil, water, light, and temperature greatly influences the ratooning ability. These interactions are needed to be studied properly for manipulating ratooning ability agronomically.
Rice ratooning depends on the ability of dormant buds on the stubbles of the crop to remain viable, the buds may be at different stages of development or similar in length. Auxiliary buds that developed at those bud nodes grew into ratoon tillers. Tillers regenerated from higher nodes formed more quickly, grew faster and mature earlier. The panicles from ratoon coming from lower nodes produced more grains per panicle than those from upper nodes, but their fertility percentage decreases. However panicles from upper nodes contribute more to ratoon yields than those from lower nodes.
The best time to harvest the main crop for raising a good ratoon crop is when its culms are still green; stalks should be cut before the main crop is fully matured. The better yield from ratoon crop is reported if main crop stubble is left with 2-3 nodes. Sowing time, temperature, day length and other factors have a profound influence on main crop duration, harvest date of the main crop and its effect on the rice ratooning also vary. Very little work has been done on this aspect. However, any delay in planting the main crop will delay the harvest and effects ratoon crop yield as well.
The success of a good ratoon crop depends on the care with which the main crop is cultivated in the growing season. Agronomic practices and the care with which the main crop is protected against insect pests and diseases determine the success of ratooning and crop yields in ratoonable cultivars. Reduction in tilling ability and yield of the ratoon significantly are reported by low temperature at post maturity, similarly, blast incidence on the main crop can carry over to the ratoon resulting in total failures. Ratooning provides higher resource use efficiency per unit time and per unit land area. However, better yield of ratoon crop is possible by adopting appropriate management practices for main crop as well as for ratoon crop.
These management practices include land preparation, adequate plant density and spacing, use of appropriate cultivars, water management, application of adequate rate of fertilisers, appropriate height of cutting, and control of diseases, insects and weeds.
Following strategies should be followed for improvement of rice ratooning crop:
The prospects of ratooning should be studied under rain-fed conditions to over moisture stress during later growing phases of the crop than irrigated rice.
Major emphasis and systematic breeding efforts should be undertaken to synthesise cultivars especially for rationing. Cultivars suitable for different climate, altitude and purpose should be identified to optimise ratoon rice yields.
Efforts should be made to screen for rationing ability of rice resistance to insects, pests and diseases, tolerance for low temperature especially during early seedling stage and for drought during later stages of the crop.
Post harvest technologies including seed viability and milling quality should be studied. Development of low-cost technology in terms of bio-fertilisers, weed management to minimise cultivation cost is necessary to make ratoon rice a profitable enterprise.