Evaluation of the AquaCrop Model for Conditions of Interaction Effect of Salinity Stress in Different Growth Stages of Maize (in Qazvin Region)

The knowledge of crops response to salinity stress application methods in growth stages, can lead to better management of stresses. This research was done on the S.C 704 maize, in the mini-lysimeter space and in Qazvin region. The experiment was performed factorial and in a completely randomized design. The salinity treatments of soil saturated extract (the main factor) were applied at four levels of 1.7(S1), 3(S2), 5(S3) and 7(S4) dS.m-1. The crop growth stage treatments (sub-factor) were defined as one-stage of 6 leaves (C1), flowering (C2), seeds milking (C3) and two-stages of C1C2, C1C3 and C2C3. The research target was to simulate the maize yield by AquaCrop model, in conditions of pulsed salinity stress application in crop growth stages. The stress application data in one and two growth stages, were used for calibration and evaluation the AquaCrop model, respectively. From S1 to S4 treatment, the crop dry matter was decreased from 157.2 g. plant-1 to 115.9, 53.2, 77.7, 86.1, 97 and 46.5 g. plant-1 in the C1, C2, C3, C1C2, C1C3 and C2C3 treatments, respectively. The sudden application of salinity stress in a sensitive growth stage (C2 and C3 treatments), was caused the more damage relative to C1C2, C1C3 treatments. Because once application of salinity stress in the 6-leaf stage (C1) has caused the crop adaptation to future stresses (increasing the tolerance threshold). In AquaCrop model evaluation, the statistical parameters of CRM, EF, R2, RMSE, NRMSE and ME were equal to -0.084, 0.833, 0.91, 12.05, 11.34% and 18.32, respectively. Those showed good accuracy of AquaCrop model in simulation the maize yield. As a result, by management the salinity stress in crop growth stages, will be reduced the negative effects on the maize yield. With simulation the crop yield by AquaCrop model, different stress application states can be evaluated.