Validation of the fao aquacrop model for irrigated hot pepper (capsicum frustescensvarlegon 18) in the coastal savannah ecological zone of Ghana

Abstract

Validation of FAO AquaCrop model for irrigated hot pepper in the coastal savannah of Ghana was carried out using two field experiments between August, 2014 and January, 2015 at the School of Agriculture Research and Teaching Farm, University of Cape Coast in the Central Region of Ghana. The first experiment’s results were used to calibrate the model while the second were used to validate the model. Experimental design was the Randomized Complete Block Design consisting of four treatments (T1-T4) of different levels of irrigation water applied: T1- full irrigation (100%), T2-90% irrigation, T3-80% irrigation and T4- 70% irrigation. They were replicated three times (R1-R3). Agronomic parameters such as plant height, canopy development, and yield production along with water productivity of hot pepper were used to assess the effect of deficit irrigation on the growth and yield of the hot pepper and also used as parameterized variables for the calibration of the model. The optimum water requirement determined for the hot pepper ranged from 315.7mm to 318.3mm while the total fruit yield varied from 0.31t/ha to 1.20t/ha. However, the level of irrigation water affected the plant height, the canopy cover and the yield. Water productivity was also affected by total fruit yield in proportion to water applied. The AquaCrop model was validated and results obtained from the model agreed quite well with measured data. In general, the model performed well for the crop water requirement for all the treatments, water productivity predictions and the fruit yield but less satisfactorily for canopy development.