Performance evaluation of AquaCrop model for Okra crop under Tarai condition of Indo-Gangetic Plain

Abstract

Crop growth simulation models are used for predicting the effects of soil, water and nutrients on grain yield and biomass. The impact of deficit irrigation on crop growth and yield was simulated using AquaCrop model with a view to conserve irrigation water and energy. These models are tested for a given region using the data generated from field experiments. In this study a water driven crop growth model was tested for Okra crop under varying irrigation regimes. The study area comes under climatic zone of western Himalayan region and is located in the Shivalik foothills of the Himalayas and represents the Tarai region of Uttarakhand state. The field experiment was conducted at the experimental farm of College of Technology, GBPUA&T Pantnagar, Uttarakhand during 2014. The irrigation treatments comprised of all possible combinations of full irrigation or limited irrigation is such that T (full Irrigation i.e. 100% level of estimated 1 crop water requirement through drip), T (80% of level of estimated crop water require- 2 ment through drip), T (60% of level of estimated crop water requirement through drip) 3 and T (Furrow Irrigation). The performance of the model was tested using statistical 4 parameters like model efficiency (E), coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE). It was observed that the model was calibrated for yield and biomass with the prediction statistics 0.96 < E < 0.97, 0.34 < RMSE < 0.50 and 0.19 < MAE < 0.30 t ha-1 for different irrigation levels. The model was validated for fruit yield and biomass with all treatment combinations with prediction error statistics values 0.90 < E < 0.91, 0.30 < RMSE < 0.42, 0.89 < R2 < 0.91 and 0.11 < MAE < 0.25 t ha-1. It was observed that the AquaCrop model was more accurate in predicting the Okra yield under full and 80% of FI through drip irrigation as compared to flood irrigation methods. The AquaCrop model predicted yield and biomass of Okra with good accuracy under different irrigation regimes. The tested results of this study on AquaCrop can be used as a planning tool to assist management decisions under changing climatic situations.