Significance of Weather Variables during Critical Growth Stages for Hybrid Rice Production in Subtropical India

Rice (Oryza sativa L.) production with available cultivars under changing climatic condition is a major concern in subtropical India in the context of food security. This warrants a need for introduction of hybrid rice cultivars having higher genetic potential to achieve higher production per unit area. It is in this context, the present investigation is planned with a major objective of studying the behavior of hybrid rice cultivars under varying weather conditions. To determine the relationship between weather variables and hybrid rice grain yield, field experiments were conducted in 2013 and 2014 at Kharagpur, India. Weather variables considered were maximum temperature (Tmax), minimum temperature (Tmin), maximum relative humidity (RHmax), minimum relative humidity (RHmin), and solar radiation (SRAD). The crop model crop environment resource synthesis (CERES)-rice was calibrated and used to simulate hybrid rice yield for varying planting dates. The weather variables Tmax, Tmin, and RHmin during basic vegetative stage; Tmin and RHmax in early reproductive stage; and SRAD in late reproductive stage were found to influence the hybrid rice yield. The optimum values of Tmax were 32.7, 32.5, and 31.2 degrees C; and Tmin were 25.2, 24.9, and 25.6 degrees C during basic vegetative, early reproductive, and late reproductive stages, respectively for increasing the yield of hybrid rice.