Impact assessment of intra seasonal temperature variations on wheat yield using CERES Wheat model

Abstract

A field experiment was conducted at Ranchi (Jharkhand) during rabi season of 2009-10 to 2011-12 with wheat cultivar K 9107 sown on three dates (Nov 20,Dec 5 and Dec 20) to calibrate and validate the CERES-wheat model. There was a good agreement between simulated and observed wheat yields, days to anthesis and days to maturity. The validated model was used to study the impact of intra seasonal temperature variation on wheat. The sensitivity analysis of CERES wheat model, with respect to temperature variations and wheat yield, revealed that increase in temperature above the normal values to 3 oC, showed considerable yield reduction (12- 17 per cent) under different sowing dates. Similarly, with decrease in seasonal temperature up to 3oC, the yield enhancement by 12-16 per cent was observed. Sensitivity of CERES wheat model to incremental units of intra seasonal temperature showed a gradual decrease in yield as well as days to maturity under varied sowing dates. Increase in temperature ( 3 oC from normal) during 2nd fortnight of January (16-31st ) was observed to be the most detrimental for wheat crop with respect to its yield for timely sowing date (20thNov) whereas it would be maximum during 2nd fortnight of February (15-28th) for moderately normal sown (5th Nov) and late sown crops (20thDec).