Effect of drought stress, mycorrhiza and zinc rates on agro-physiologic characteristics of maize cv. KSC704

To study the effect of drought stress, mycorrhiza and zinc rates on agro-physiologic characteristics of maize (cv. KSC 704), a field experiment was carried out in factorial arrangement using randomized complete block design with three replications at research field station of College of Agriculture and Natural Resources, Islamic Azad University, Arak, Iran, in 2006 and 2007 cropping seasons. The experimental factors included of three levels of irrigations: irrigation equal to crop water requirement (control), irrigation equal to 75% of crop water requirement and irrigation equal to 50% of crop water requirement, inoculation with mycorrhiza fungi (Glumus intraradices) at two levels: inoculation with and without, and zinc sulphate at three levels: 0, 25 and 45 kg.ha-1. The results of combined analysis of variance showed that, drought stress significantly affected water use efficiency, root dry weight, grain yield, biologic yield and harvest index. Drought stress reduced grain yield, biologic yield and harvest index but increased water use efficiency. Effect of mycorrhiza was also significant on traits of root dry weight, percent of root colonization and biologic yield. Inoculation with mycorrhiza improved the concerend traits as compared to control. Application of 45 kg.ha-1 zinc sulfate significantly increased biologic yield, however, increases in grain yield was not significant. The highest root dry weight and percentage of root colonization was observed in 25 kg.ha-1 zinc sulfate. Inoculation with mycorrhiza improved concerned traits as compared to non- mycorrhiza not only in optimum irrigation level but also in drought stress conditions. Irrigation  mycorrhiza  zinc interactions on root dry weight, grain yield, biologic yield, harvest index and water use efficiency was significant. The highest grain yield was obtained from optimum irrigation (control) + no mycorrhiza + 45 kg.ha-1 zinc sulfate. It is concluded that with irrigation equal to 75% of water requirement + inoculation with mycorrhiza + 45 kg.ha-1 zinc sulfate obtain optimum yield.