Study the Effects of different irrigation levels on yield of new maize Hybrids (single cross 302 and 500) in different plant densities using sprinkler system.

In order to evaluate the effects of different levels of sprinkler irrigation on yield, yield components and water use efficiency of two corn cultivars KSC500 and KSC302. two experiments were carried out in 2006 and 2007 in the experimental field of Agriculture Engineering Research Institute in Karaj. In each experiment, experimental design was laid out as split plot design based on randomized complete blocks with three replications. In the first expriment for KSC500 variety, main plots were three irrigation levels: 75%, 100% and 125% ET and sub plots were three plants densities: 75000, 85000 and 95000 plant per hectare. In the second experiment for KSC302 cultivar, main plots were three irrigation levels: 75%, 100% and 125% ET and sub plots were three plants densities: 80000, 90000 and 100000 plant per hectare. In each irrigation interval; the volume of used water was calculated on the basis of the soil moisture deficit to the level of field capacity in the depth of root zone. Irrigation time was considered based on 50 percent of MAD of controlled treatment. Vir 50 spinkler model was used for irrigation sub main plot. Crop was planted with 75 rows spacing centimeter in June. Also it was planted in 6 rows with 12 meters length. The results showed that increasing the levels of irrigation from 75% to 125%, has a significant effect on yield and yield components of two corn cultivar KSC500 and KSC302, but its effects on water use efficiency of two corn cultivar was not significant. In the first experiment (KSC500), 75% ET treatment had the best WUE (0.944 kg/m3) and in the second experiment (KSC302) , 100% ET treatment had the best WUE (1.22 kg/m3). Effect of different densities on yield, yield components, and water use efficiency of two corn cultivar was not significant. According to the results, for corn cultivar KSC500, 125% ET treatment and 85000 density and then 125% ET treatment and 75000 density had the best yield, yield components, and water use efficiency. Also for corn cultivar KSC302, 125% ET treatment and 90000 density had the best yield and yield components, and 100% ET treatment and 100000 density had the best WUE.