Estimating crop yield under conditions of soil water deficit and salinity stress with crop water productivity model

Abstract

The aim of this study was to simulate grain yield, biomass production, canopy cover and water productivity of winter wheat grown under soil water deficit and salinity stress by AquaCrop model. Five different irrigation strategies (S100 - S75 - S50 – S25 and S0) and 5 different irrigation water salinity levels (T1 = 0.3 dS m-1, T2 =5 dS m-1, T3 = 7.5 dS m-1, T4 = 10 dS m-1, T5 = 15 dS m-1) were used with the model to estimate deficit irrigation and salinity stress scenarios. According to estimation of the model the grain and biomass yields were fluctuated in the range of 5.43-8.00 t ha-1 and 12.84-17.67 t ha-1 at irrigation treatments. The application of 25%, 50% and 75% level of deficit irrigation, grain yield reduction was obtained 5%, 13% and 26% respectively. It was compared to the T1 (control) treatment, a low value of 3% was obtained for the T2 treatment. Yield loss of T3 and T4 salinity treatments were found to be 19% and 43% respectively. The crop yield reduction was dramatically (86%) at 15 dS m salinity level of irrigation water. The lowest yield was obtained at all salinity levels in I25 treatment, where 75% water saved. The highest and lowest water productivity was 1.28 kg m-3 and 1.20 kg m-3 respectively. It is possible to irrigate much more areas saving water with deficit irrigation and also the yields obtained from these areas were 2.17, 6.17 and 17.2 tons more than the yields obtained from areas irrigated with full irrigation. For, sustainable water management in agriculture area, using simulation model such as AquaCrop is useful tolls to estimate effect of applied water depth and quality of irrigation water on crop yield.