Calibration and Validation of Reproductive Stages of Wheat Varieties with CERES-Model under Sowing Environments in Irrigated Conditions of Jammu, India

Impact of heat stress during March and April months have significant reflections on the occurrence of phenological stages of wheat. The current investigation aimed to analyze the impact of three varieties of wheat planted in three different environments (dates of sowing) and three levels of nitrogen to study their effects with respect to the occurrence of reproductive stages. Field experiments were conducted with three wheat varieties viz., HD 2967, RSP 561 and WH 1105, which were sown in 3 sowing environments/dates, viz., 25^th October-early, 14^th November-normal and 4^th December-late and 3 levels of nitrogen, viz., 100, 125 and 150 kg/ha randomized in 3 replications under a split-split plot design in rabi season 2015–16 and 2016–17. The experiment was sown at the Agromet Research Farm of Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu (SKUAST-J), Chatha. Experimental conditions and results obtained from the experiments were used as a database for calibration of Crop Environment Resource Synthesis (CERES)-a Wheat model under Decision Support System for Agrotechnology Transfer (DSSAT) version 4.6 package for studying the effects of changing climatic conditions on wheat phenology. The varietal specific genetic coefficients were calibrated and validated for all the 3 wheat varieties. On comparison of the results obtained from the calibration and validation data of various wheat varieties; the researchers came to a very good and valid conclusion to predict the days of occurrence of various phenological stages of wheat. The parametres R², d-stat, RMSE and nRMSE were used for comparing CERES-Wheat model results with the actual data and the values were excellent.