Response of some maize hybrids to water stress

Introduction Maize is the cereal with the largest annual global production at 1000 M tons annually. Maize (Zea mays L.) along with wheat and rice provides at least 30% of the food calories to more than 4.5 billion people in 94 developing countries where one-third of world children are malnourished. By 2050, the demand for maize in the developing will be almost double to the current demand. However, an estimated 15% to 20% of maize grain yield is lost each year due to drought and such losses may further increase as droughts become more frequent and severe because of climate change. Cultivation area for maize grown in Iran was about 350000 ha with 1.25 million tons production in 2014. But drought stress in recent years and poorly water sources could limit maize cultivation in Iran. Materials and methods In order to evaluate of drought stress effects on yield and it’s components in some maize hybrids, also determine drought tolerant genotypes, 8 maize hybrids was studied as three experiments under normal, drought stress in vegetative stage and drought stress in reproductive stage. Experiment was conducted using RCBD design with three replications in training field of Kermanshah education center. Some agronomic traits such as plant height, ear per plant, ear length, ear diameter, ear cob diameter, row per ear, seed per ear, 100 seed weight, grain yield based on 14% moisture, ear weight, ear cob weight, seed depth, leaf area, stem diameter and days to physiological were recorded. Because of numerous recorded traits, in result and discussion section just some of most important yield components have been explained. Results and discussion Analysis of combined variance showed that drought stress had significant effect on all recorded traits. Some yield components such as 100 seed weight, seed per row and rows per ear reduced mostly due to drought stress. Above traits due to drought stress reduced 25.6, 19.1 and 17.6 percent, respectively. Among evaluated traits, drought stress reduced grain yields more than any other traits. In fact, cumulative reduction in component yield caused significant reduce in grain yield. Then grain yield under drought stress in vegetative and reproductive stages reduced 13.7 and 28.7 percent, respectively. Maize hybrids were different statistically for all recorded traits. Hybrids Ksc260, Ksc704 and Ksc647 had high grain yield under both normal and drought stress conditions. Drought tolerance indices confirmed above issue so that these hybrids had high potential for grain yield also partial drought tolerance. Among above hybrids, Ksc260 had well characteristics to cultivate in regions with drought stress conditions. Conclusions Among evaluated traits, drought stress reduced grain yields more than any other traits. In fact, cumulative reduction in component yield caused significant reduce in grain yield. There were well variation among evaluated hybrids and it could be identify some drought tolerant hybrids among them. Among evaluated hybrids, Ksc260 with high grain yield under normal and drought stress conditions also early maturity had well characteristics to cultivate in regions with drought stress conditions. Besides Ksc260, Hybrid Ksc704 had high grain yield under both conditions but this hybrid is ale maturity and it,s water requirement is more than Ksc260 so it suggested that Ksc704 cultivated in areas with no water limited