Effects of water deficit and mycorrhizae on grain yield, reproductive and physiological traits of corn hybrids

Increasing crop production to ensure future food security while reducing environmental pressure on agro-ecosystems requires improved water and nutrient use efficiency. the arid and semiarid regions of the world lack of sufficient water supply is the major problem for corn cultivation and is a restriction for its production, so studies on the growth limitation and germination of corn seeds under drought conditions seems very necessary. The effects of drought on plant growth depend on several factors such as plant genetic resistance, stage of growth and duration of plant expose to drought. The AMF are playing a vital role in sustainable agriculture because they enhance plant water relations, which improve the drought resistance of host plants. It is important to increase our understanding of AM fungal and maize genotype interactions and water condition on the symbiosis, and on the physiology and nutritional status of maize plants. Thus Mycorrhizae application and choosing suitable cultivar are of simple managements in decreasing drought effect. This investigation had done in order to investigate effect of irrigation regimes (irrigation after 70, 110 and 150 mm evaporaation from evaporate basin), Mycorrhizae (non application and application of Mycorrhizae) and cultivar (704 and 640) on growth and yield of maize. A split factorial experiment based on randomized complete block design with three replications was conducted during growing season of 2015 at Islamic Azad University, Malekan Branch, Plots were then furrow irrigated in the mornings every week. Each block was including 12 plots. The size of each plot was 3.5m×4m, and there was in each plot, 5 rows with a distance of 75 cm, and the length of 4 m. The distance between plots was selected 150 cm, and the distance between blocks was selected 3 m. By mid August an area of 2.5 m from 3 line of plot area was separately harvested and traits were evaluated. MSTAT-C and EXCEL were used to analyze data and draw graphs, respectively. Based on results of this investigation, response of cultivars to drought were different. In irrigation after 70 mm evaporaation from evaporate basin in 704 cultivar highest grain yield observed. In cultivar 704 both irrigation after 110 mm evaporaation from evaporate basin and irrigation after 150 mm evaporaation from evaporate basin decreased grain yield by 19 and 50.6 % in grain yield, but in 640 cultivar that had higher grain yield in control than 704, drought did not had significant effect on grain yield. Mycorrhizae also increased grain yield by 25.2 %. All three factor of drought, Mycorrhizae and cultivar caused changes by changing both yield component of grain number and 100 grain weight. It seems drought caused a decrease in grain number by decreasing number of total floret and increasing unfertile floret number, but Mycorrhizae had opposite effect that this decrease in floret number can caused by gap increase between tasseling and silk emergence. Drought did not had effect on chlorophyll a, but it decreased chlorophyll b, but Mycorrhizae caused an increase in chlorophyll b. Drought and Mycorrhizae increased catalase and Peroxidase content. We then suggest potential areas for future research related to (a) the adoption of cropping practices promoting AM colonization and survival; (b) the further understanding of AM effects on maize morpho-physiology; and (c) the creation of AM-colonized, drought-tolerant maize cultivars through conventional breeding as well as molecular and genomic techniques