Field experiments were carried out during 1997 to 2007 at B. A. College of Agriculture, Anand with two dates of sowing (D1 : Onset of south-west monsoon and D2 : 15 days after onset of south-west monsoon), two cultivars (Robut 33-1 and GG-2) and two irrigation regimes (I1 : Rainfed and I2 : Irrigation at 50% ASM) for assessing the impact of weather parameters on pod yield of kharif groundnut. Results revealed that groundnut crop sown at the onset of monsoon performed better than late sown crop sown 15 days after onset of monsoon rain and on an average, the early sowing gave 21.4% higher pod yield. Robut 33-1 produced more pod yield than the local variety GG-2 in most of the years and on an average, Robut 33-1 yielded 21.6% higher pod yield. During the years of dry spells, irrigations applied at 50% ASM (I2) recorded greater pod yield than the crop grown under rainfed condition (I1). In case of crop sown at onset of monsoon, mean temperature during pod development phase showed significant positive correlation with pod yield, whereas in second sowing crop, minimum temperature at 50% pod development phase and sunshine hours at pod development phase also had significant positive correlation with pod yield. Regression models developed were able to account for 38% variation in pod yield in crop sown at onset of monsoon (D1) and 85 to 92% variation in crop sown 15 days afteronset of monsoon (D2).

CERES (Crop Environment Resource Synthesis)-wheat model (DSSAT v 3.5-Decision Support System for Agrotechnology Transfer) was calibrated and validated for wheat cv. GW-496 at Anand using experimental data collected under different management practices (Date of sowing x Irrigation) during 1995-2007. Results showed that optimum sowing date (D2–15th Nov.) validation was found better as compared to early (D1–1st Nov.) and late (D3–30th Nov.) sowings. The validation of model for different irrigation regimes showed that the performance of model was poor in treatment having less irrigation (I1 and I2). The model performance was found good and satisfactory in treatments having 6-7 irrigations (I3 and I4). On an average, the performance of model for I4 treatment was found good. This showed that model worked better under optimum sowing with optimum irrigation. The various test criteria for evaluation of model showed that highest correlation was observed in D2I3 treatment. The lowest MAE was observed in D3I3 treatment. Similarly, lowest MBE (12.77), lowest RMSE (46.04) and highest index of agreement (1.0) were observed in D1I4 treatment. The error per cent by CERES-wheat model showed that in majority of the cases the models had underestimated wheat yield. Per cent error ranged between -0.020 to -56.02. The average per cent error was found lowest in D1I4, D2I4 and D3I3 irrigation treatments as compared to other treatments. This showed that the model worked good in all model test criteria. In a nutshell, the validation results showed that the model worked better under optimum sowing with optimum irrigation as compared to early/late sowing and moisture stress conditions.

A field experiment was conducted during the kharif seasons of 2009 and 2010 to evaluate the CROPGRO-Peanut model for phenological and yield attributes of three groundnut cultivars V1-M 335 (Virginia spreading type), V2-GG 20 (Virginia semi-spreading type) and V3-GG 5 (Spanish bunch type) sown under three environments. Model output showed that the simulated values of phenology, growth parameters and pod yield of the groundnut cultivars were close to the corresponding observed values.