OPTIMUM TRANSPLANTING DATES FOR RICE IN KERALA, INDIA, DETERMINED USING BOTH CERES V3.0 AND CLIMPROB

Rice (Oryza sativa L.) is an important food crop for more than half th e world's population. It grows best under shallow flooded conditions. For establishing a healthy rice stand in a flooded field, the seedling s of the crop are first grown in nurseries and then transplanted into the field. At a specific location, transplanting dates determine how g rowing conditions later in the season will affect the rice crop. Dry c onditions after ripening, favorable to maintaining the quality of rice through harvest, may be more or less likely to occur, depending on th e transplanting date selected. The objective of this study was to dete rmine optimum transplanting dates for rice at five locations in Kerala , a monsoon-affected state in southern India. Optimal transplanting da tes were derived based on two approaches: (i) probabilities of rainfal l events using ClimProb, a PC-based software package, and (ii) target yields simulated by the CERES-Rice v3.0 crop growth simulation model. Under rainfed conditions, the optimum transplanting dates were from th e 23rd to 26th week for multiple cropping in a year, and from the 26th to 32nd week for a rainfed monocrop, The ClimProb approach used here can be adopted for use elsewhere if climate data are available, and th e model approach ran also be adopted if specific weather, soils, and c rop information is available.