The Evaluation of OILCROP-SUN Model for Simulation of Growth and Yield of Sunflower (Helianthus annuus L.) Hybrids Under Different Agro-Ecological Conditions of Pakistan.

Sunflower is an important oilseed crop across the world. As a deep rooted crop, it can tolerate water and nutrient stresses and can be grown as a rotation crop in many different systems. Crop growth models can be an alternative research tool for simulating the growth and yield of sunflower hybrids. The objectives of the present study were to evaluate the performance of the OILCROP-SUN model for three contrasting environments, including arid, semi arid and sub humid conditions and to determine the effect of nitrogen fertilizer rates on different sunflower hybrids for these same environments. Field experiments were conducted at three different locations to determine the impact of nitrogen fertilizer on grain yield. The OILCROP-SUN Model (V 4.0.2) was used to simulate growth, development yield of sunflower. The model was calibrated with the experimental data for 2008. The model was able to predict phenological development for all sunflower hybrids reasonably well, with a RMSE between observed and predicted days that ranged from 0 to 1.3 days For achene yield, the RMSE ranged from 261 to 285 kg ha^-1 and for total above ground dry matter the RMSE ranged from in case of TDM values 2604, 1264, and 2517 kg ha^-1 during model calibration for hybrid Hysun-33, Hysun-38 and Pioneer-64A93, respectively. The OILCROP-SUN model was validated for achene yield using data from experimental trial carried out during 2009. The RMSE was ranged from 348 to 1420 kg ha^-1 among all experimental locations of Punjab-Pakistan. The model suggested that Hysun-38 with 180 kg N ha^-1 gave best performance at all experimental locations of Punjab-Pakistan.

Keywords: Crop simulation; sunflower; DSSAT; Decision support system, nitrogen management, Punjab, Pakistan.