Phasic Development of Rice During the Present and Future Climatic Conditions in Central Zone of Kerala

Abstract

Rice is a staple food and its demand is substantially increasing with the growth of the global population. Phenological development was found to play a significant role in the distribution of carbon among plant organs, which has an impact on rice yield. Temperature affects plant phenology, and the current rapid climate change has revived interest in understanding and modelling plant phenology response to the warming trend. Two rice varieties viz., Jyothi (short duration variety) and Jaya (medium duration variety) were raised at Agriculture Research Station, Mannuthy, during the kharif season of 2021 and phenological observations viz., days to 50% flowering and physiological maturity were recorded. The phenophase has been also predicted from the Info-Crop and CERES-DSSAT for both varieties during the experimental period for validation. To study the phenology changes in future conditions i.e., near (2030), mid (2050) and end (2080) century, future weather data has been downloaded from the GFDL-CM3 climate model under RCP 4.5 and RCP 8.5 scenarios. Using the projected weather data, the phenophase of both varieties has been predicted using Info-Crop and CERES-DSSAT models. During the base period, Jyothi took 71 days and Jaya took 75 days to reach 50% flowering, while the total duration was found to be 101 days in Jyothi and 108 days in Jaya. In the case of 50% flowering, CERES-DSSAT predicted more accurately for Jyothi while InfoCrop predicted more accurately for Jaya. The prediction of physiological maturity was found to be more accurate using CERES-DSSAT in Jaya and Info-Crop in Jyothi. Validation results showed that both models can be used to predict the phenophases of rice varieties. The predicted duration during base period was compared with future duration. In Info-Crop model, the days to 50% flowering of Jyothi variety in near, mid and end century is expected to reduce by 3, 3 and 4 days in RCP 4.5 scenario and 1, 3 and 4 days in RCP 8.5 scenario whereas for Jaya variety, it is by 2, 3 and 3 days in RCP 4.5 and 1, 3 and 3 days in RCP 8.5 scenario respectively. CERES-DSSAT model predicted reduction of 50% flowering duration of Jyothi variety in near, mid and century by 1, 2 and 3 days in RCP 4.5 scenario and 1, 2 and 2 days in RCP 8.5 scenario whereas for Jaya variety, the reduction is by 2, 2 and 3 days in RCP 4.5 scenario and 1, 2 and 3 days in RCP 8.5 scenario respectively. The physiological maturity is projected to shorten by 3-6 days in Jyothi and 4-5 days in Jaya, by the end century. Results showed that the temperature rise in future can cause the considerable reduction in duration to attain 50% flowering and physiological maturity of rice varieties.