Assessing Impact of Projected Climate Change on Sali Rice in a Representative District of Upper Brahmaputra Valley Zone of Assam

Three years of field trial along with DSSAT v4.6 CERES-Rice model-based simulation experiment was carried out to study the impact of climate change on Sali rice yield under various Representative Concentration Pathways (RCPs) in the agro-climatic conditions of Jorhat, Assam. Field experiments were conducted during kharif, 2017, 2018 and 2019 at the Instructional-Cum-Research (ICR) farm of Assam Agricultural University, Jorhat with three varieties viz., Mahsuri (150 days), Swarna Sub-1 (140-145 days) and TTB-404 (140-145 days); transplanted under three different micro-climatic regimes created by manipulating date of transplanting i.e., 26th June (early), 11th July (mid) and 26th July (late) under split plot experimental design with four replications. The validated model showed a good agreement for estimation of days required to attain different phenological stages with RMSE value 3.5, 2.9 and 2.9 days for Swarna sub-1; 2.4, 3.3 and 4.1 days for Mahsuri and 3.7, 2.6 and 2.4 days for TTB-404, respectively for panicle initiation, anthesis and physiological maturity. The overall d-stat value varied within 0.53 to 0.85 for phenology and 0.68 to 0.79 for grain yield. The ensemble weather data under four RCPs revealed an increase in mean maximum (0.3 to 3.0°C) and minimum (0.8 to 3.5°C) temperatures along with rainfall (11.8 to 43.4%) during the crop growing period compared to experimentation period (i.e. 2017-19) in three projected years. The grain yield of Sali rice showed positive deviation in all four RCPs and projected years under successive transplanting dates. The overall results reveal an increase in mean temperature up to 3°C during the crop growing period has no substantial adverse impact on grain yield of Sali rice under the agro-climatic condition of Jorhat, Assam.