RICE RATOONING - IRRI books - International Rice Research Institute

Production practices for ratoon ricein Tungabhadra River ProjectK. S. Prakash, K. Krishnamurthy, Y. C. Panchal, and B. G. PrakashAgricultural Research Station, Siruguppa, University of Agricultural Sciences,583121, India.About 0.2 million hectares of the irrigated area of northern Bellary and Raichurdistricts, Karnataka, are fed by the Tungabhadra River Project (TRP) canals(Fig. 1). The climate is characterized by high temperatures, adequate solarradiation, and low rainfall (Table 1). The climate is ideal for cultivating irrigated rice.Rice is grown mainly in autumn and summer. The autumn crop is normally a longdurationvariety. The summer crop is a medium-duration variety which can beharvested before the canal is closed, normally by the end of April. Until recently, ricewas thought to be a problem-free crop providing farmers stable income. Blastdisease is relatively unknown, but recent outbreaks of brown planthopper (BPH)have caused great losses to the rice crop.Need for rice ratooning in the TRP areaIn 1985, insufficient rain in the catchment area lowered water in the Tungabhadrareservoir. Silting, frequent breaches in canals, and improper water managementhave accentuated the scarcity of irrigation water, particularly during summer. In1985, the canals were reopened late in the season in July, and little time was left forcultivating a second crop. Rice growers were cautioned not to plant a second ricecrop because of receding water in the reservoir. However, the unsuitability ofricelands for alternative crops forced farmers to grow a second crop despite repeatedwarnings. Consequently, there was an increased demand for short-duration ricevarieties in the summer of 1986, even though their grain quality is inferior and yieldsare low.For these reasons, we are exploring ratooning the autumn main crop insteadof planting a second rice crop. Zandstra and Samson (3) indicated that ratoonedrice, which has a shorter duration than the main crop, has the potential to increaseyields where cropping intensity is limited by inadequate irrigation. It also costs less togrow a ratoon crop than a new crop. Mahadevappa (2) reported that an Intanratoon crop yielded 140% of the main crop. This cultivar, however, is notrecommended for irrigated northern areas of Karnataka. Ratoonable genotypesmust have good grain quality to meet standards of rice mills.Rice ratoon cropping was summarized by Chauhan et al (1). Successful ratooncropping requires proper cultural management for the main and the ratoon crops.Although heavy insect pest incidence reduces ratoon crop yields, no suitable