Yield Prediction, Sensitivity Analysis and Calibration of DSSAT Crop Model for Different Cultivars, Establishment Methods and Nitrogen Levels in Rice (Oryza sativa L.) Under Normal and Varied Temperatures

Rice is one of the important cereal crops grown throughout the world. There are various factors like climate, soil, variety and management are influencing the growth and yields of rice. Selection of best performing cultivar, proper irrigation scheduling and nutrient management techniques can play a key role in improving the productivity of rice. To evaluate these constraints the data was taken from an experiment conducted for two years during kharif 2009 and 2010 at Water Technology Centre, College Farm, Rajendranagar, Hyderabad and was used to calibrate and evaluate the DSSAT model for rice. In the experiment, there were three cultivars (Tellahamsa, IR 64 and MTU 1010), two crop establishment methods (Aerobic rice and transplanted rice) and five nitrogen levels (100,150, 200, 250 and 300 kg ha⁻¹) which were laid in split –split plot design. The inputs like soil data, weather data, crop data, genetic coefficients, irrigation scheduling and harvesting dates were given to the model for calibration and validation. The observed and model predicted yields were evaluated and the outcome revealed that the predicted values were statistically similar to the observed values with a mean RMSEn of 2.26 and 22.2 for crop establishment methods, 2.02 and 18.87 for cultivars and 4.43 and 16.01 for Nitrogen levels during the years of study. The sensitivity analysis when performed with 1°C increase and decrease in temperature significantly affected the rice yield. The decrease in daily maximum and minimum temperatures of the region has increased the yield. However, the increase in temperature forecast a drastic reduction in the grain yield of rice.