Journal of Hill Agriculture

A field experiment on various cultivars and N levels on rice was carried out for identifying their growth and yield performance under humid sub-tropical climate of Chitwan, Nepal during rainy season of 2008. The simulation study for different agronomic and climate change parameters was also done concurrently by the use of CSM-CERES-Rice model embedded in DSSAT ver. 4.0. The experiment was laid out in 2 factorial RCBD with three replications consisting three varieties: hybrid ‘Prithivi’, improved check ‘Masuli’ and scented basmati ‘Sunaulo Sugandha’ and four levels of nitrogen: 40, 80, 120 and 160 Kg ha⁻¹. Soil of experimental field was loamy sand in texture where in initial content of soil available N, P and K was medium in surface horizon and lower in sub surface horizon. Significantly higher grain yield (5.71 t ha⁻¹) was obtained for Prithivi with 160 Kg N ha⁻¹. The ancillary attributes viz. plant height, leaf area index (LAI), tillers m⁻² and total dry matter production were significantly correlated with grain yield (r=0.58, 0.59, 0.89 and 0.84), respectively. The model calibration was performed with 160 Kg N ha⁻¹ for Prithivi and Sunaulo Sugandha and 120 Kg Nha⁻¹ for Masuli and the model validation was found to be satisfactory. The model was found sensitive to various scenarios of climate change parameters like weather years and different amplitudes of weather variables and other agronomic parameters viz. transplanting date, crop geometry and doses of N. Increment and decrease in maximum and minimum temperature (± 4°C), CO₂ concentration (+20ppm) with change in solar radiation (±1MJ m⁻² day⁻¹) resulted maximum increase in yield (by 62, 41 and 42%) under decreasing climatic scenarios in Prithivi, Masuli and Sunaulo Sugandha, whereas maximum decrease in yield (by 80, 46 and 40%) was recorded under increasing climate change scenarios, respectively. Similarly Prithivi showed 13% decline under early transplanting (July 1) where as Masuli and Sunaulo Sugandha predicted 13 and 19% of yield loss by 20 days of delaying in transplanting (July 31) than the standard transplanting (July 11). Simulated yield of Prithivi was reduced by 5% for closer geometry of 20×20 cm² and increased by wider geometry of 30×30 cm² with reference to 25×25 cm². N stressed (control) in Prithivi, Masuli and Sunaulo Sugandha reduced the yield by 17, 34 and 38%, respectively with maximum loss in improved check and scented varieties. Results showed that the CSM-CERES-Rice model could be a good tool for acquiring précised decision on the allocation of scarce resources and to increase the efficiencies of inputs in the hilly and inner-terai regions of central Nepal under the burning scenarios of global climate change.