Yield-water function of middle-aged and early varieties of maize (KSC 500 & KSC 302) under sprinkler irrigation system

In this research, the effect of different levels of sprinkler irrigation and planting density on yield and Water Use Efficiency (WUE) of middle-aged and early varieties of grain maize (KSC500 and KSC302) evaluated under sprinkler irrigation method for two years in Karaj. This research was carried out as two independent split plot experiments in a randomized complete block design with three replications. The applied water levels in both experiments were the same (three irrigation levels: 75,100 and 125% of the Etc). However, according to the variety, in each experiment, the planting densities were different (in the case of KSC500 variety, sub plots were three plants densities including 75000, 85000 and 95000 plant per hectare and in the case of KSC302 variety, three plants densities including 80000, 90000 and 100000 plant per hectare were considered. The results showed that increasing the depth of irrigation water significantly increased the grain yield of maize. However, different planting densities had no significant effect on yield and WUE of the mentioned cultivars. Based on the results in the range of the irrigation depth from 700 to 1000 mm, the yield of maize varieties was linearly increased. However, with further increase in the depth of irrigation water, the slope of the relationship between the yield and irrigation water decreased significantly. In the first experiment (KSC500), applying 75% of the ETc has led to the highest WUE (0.944 kg/m3) and in the second experiment (KSC302), applying 100% of the has led to the highest WUE (1.03 kg/m3). Finally it can be concluded that under limited water resources conditions, planting early and middle-aged varieties of maize, using proper irrigation scheduling and applying about 9500 m3/ha of irrigation water in Karaj region under sprinkler irrigation method, can lead to an increase in maize WUE up to 1 kg/m-3 or more.