Evaluation of the impact of climatic trends and variability in rice–wheat system productivity using Cropping System Model DSSAT over the Indo-Gangetic Plains of India

Indo-Gangetic Plains (IGP), accountable for the regionʹs food security, has undergone climatic fluctuations and variability during the last three decades under the influence of natural or fast trend of population growth, urbanization and industrial development. The objective of this study is to understand the trends of climatic variables over 5 selected locations during the last 25–30 years and the variability of recorded and simulated rice–wheat system yield using DSSAT-CSMv4.5. There was no significant change in rainfall over the years in both the rice and the wheat growing seasons at all the sites except Hisar. The annual change in the rainfall trend was −28.9 mm/year (P < 0.05) and during the rice season it was −20.5 mm/year (P < 0.01) for Hisar. Incidentally, higher coefficient of variation of 79% has been noticed in annual rainfall. The district average yields of rice varied from 0.9 t/ha at Samastipur to 3.8 t/ha at Ludhiana. Rice yields decreased from the west to east IGP. The time trend of rice yield ranged from −0.023 t/ha per year at Samastipur to 0.055 t/ha per year in Faizabad. Negative trends were observed in Samastipur and was statistically significant (P < 0.05). In wheat, the yield trend ranged from 0.01 t/ha per year at Samastipur to 0.096 t/ha per year in Hisar. All the sites had a positive yield trend and at three stations (Hisar, Faizabad and Kanpur) have significant positive trends (P < 0.05). Wheat yields appeared to be increasing throughout the IGP. The comparison of observed and simulated rice and wheat yield shows that there is very good agreement between them based on Spearman correlation coefficient (rs), significant at P < 0.05 level for all the sites except Samastipur. Thus DSSAT-CSMv4.5 can be used for determining the impact of climatic variability on rice–wheat productivity.