Study of Effect of water salinity and soil fertility stresses on evapotranspiration of Maize

In order to study of effect of saline water and soil fertility stresses on the evapotranspiration of maize, a factorial experiment was conducted in a randomized complete blocks design, in the research farm of Imam Khomeini International University, in 2017. Water salinity treatments consisted of four levels; 0.5(S_0 ), 2.1(S_1 ), 3.5(S_2 ) and 5.7(S_3 ) d_s/m and Soil fertilization treatments consisted of four levels of need to nitrogen fertilizer; 100(F_0 ), 75(F_1 ), 50(F_2 ) and 25 percent (F_3 ), was conducted In three repetitions and in plots with an area of 9 square meters. By measuring the soil moisture at the root zone, at intervals between two irrigations, was investigated the difference of water absorption by stressed plots relative to non-stress plot. The results showed that by changing the salinity of irrigation water from 0.5 to 5.7 (d_s/m), in fertolity levels of F_0, F_1, F_2 and F_3, the stress coefficient of evapotranspiration (K_S ) has been; 0.77, 0.69, 0.64 and 0.6, respectively. Also, by changing the fertility level from F_0 to F_3, in salinity levels of S_0, S_1, S_2 and S_3, the K_S has been; 0.96, 0.88, 0.83 and 0.63, respectively. From treatment of S_0 F_0 to S_3 F_3, were reduced the evapotranspiration, K_S coeffition and crop yield to; 37, 37 and 38 percent, respectively. Are fitted different forms of production functions, to estimation of evapotranspiration from salinity and fertility stresses. The quadratic function was chosen as the optimal function due to having the statistics of RMSE and ME at least and R^2 and EF close to number one. The salinity and fertility stresses, has a reducer effect on the amount of evapotranspiration of plant. Therefore, by correct determination of water requirement of under stress plant, you can avoid than consumption of a lot water.