Evaluation of the sunflower yield, water productivity and soil salinity simulation under water and salinity stresses using the AquaCrop model

The AquaCrop model is a powerful tool for the simulation of crop response to the different quantitative and qualitative management of irrigation that advanced by FAO. In this study, the latest version of this model (v. 6) was evaluated for simulating sunflower yield, water productivity and soil salinity under different irrigation management using saline water. Field data were collected in order to calibration and validation of model during two crop years (2014 and 2015). The experiment was conducted as a factorial design in completely randomized blocks including two factors: the quantitative irrigation management in two levels (full irrigation and partial root zone drying irrigation in 75%) and the qualitative irrigation management in three levels (non-saline water, saline water and non-saline and saline water alternation), with three replications. While a significant reduction of 3.1-32% in grain yield were observed under water-saving irrigation treatments compared to FI (4706.7 and 4367.2 kg ha-1 in 2014 and 2015, respectively), the PRD1 treatment resulted in a slight reduction of 3.1% and 5% in grain yield, in 2014 and 2015, respectively. FI had the highest WPET (0.90 and 0.89 kg m-3 in 2014 and 2015, respectively), and PRD1, PRD3, FSI, SI and PRD2 treatments ranked next. Sensitive analysis result showed that the model sensitivity to the volumetric soil water content at soil saturation and field capacity point, maximum canopy cover, HIO, time to flowering, time to CCx and CGC is more than other input parameters.