Determination of crop water production function and response of total dry matter and grain yield to deficit irrigation in Maize

Drought and its stress are the most important factors for crop production. This research was carried out for determination of crop water production function and investigation different levels of irrigation water on yield component total dry matter, grain and harvest index in different irrigation levels for corn in Khoozestan in a research farm in Islamic Azad University, Dezfool branch in 1014-2015. It was conducted in randomized complete block design with four treatments including 60%, 80%, 100% and 120% of full irrigation (W60, W80, W100 and W120, respectively) and four replications. According to the total dry matter, grain and shot, the best crop water production function was obtained as linear function with R2 equal 0.897, 0.682 and 0.927, respectively which was significant in level of 1%. In comparison to W60 treatment, full irrigation treatment (W100) increased total dry matter yield (70%) but in comparison to W100, W80 treatment decreased total dry matter yield (5%). On the basis of total dry matter yield and grain (4.8 and 2.06 kg/ m3), maximum harvest index (0.43) and maximum water use efficiency were obtained for W80 treatment. The results show that the best grain yield and water use efficiency were related to W80.