Effects of Different Irrigation Times on Growth and Water Use Efficiency of Summer Maize

The effects of different irrigation times on growth and water use efficiency(WUE) of summer maize were studied with irrigation treatments on summer maize(Zea mays L.)grown under a rain shelter.The results showed that height and leaf area index(LAI)of summer maize decreased with the number of irrigation reduced and non-irrigation at jointing stage significantly inhibited plant height and LAI.The components of yield including ear length,ear diameter and kernel number showed falling trend with decrease in the number of irrigation.The treatment of 4 irrigations had the highest yield,and yield of the irrigation treatment at the seedling and filling stage(2 times) was the lowest with reduction of 45.38%,while the treatment of 3 irrigations including irrigation at tasselling stage could also get high output,with decline rate less than 8%.The water consumption of summer maize at each stage as well as the whole growth stage decreased with the reduction of irrigation number.Non-irrigation at either phase resulted in reduction of daily water consumption in this phase,and had some after-effects on subsequent stages.Analyses of maize moisture sensitivity index and WUE showed that the tasselling period and jointing stage were the critical periods of water demand,which should be given priority in the water management.The optimal irrigation schedule was irrigation 3 times in a normal or less precipitation year or 2 times in more precipitation year at the whole growth stage of summer maize in North China Plain.