Effect of water deficit stress and application of humic and salicylic acid on physiological traits, yield and yield components of corn

In order to study the effect of water deficit and the application of humic and salicylic acid on physiological traits, yield and yield components of corn, an experiment was carried out as a split-plot based on randomized complete blocks design with three replications at the research field of Islamic Azad Universityof Birjand, Iran in 2014. The main factor was irrigation in three levels (supply of 33, 67 and 100% water requirement) and the sub-factor was humic and salicylic acid application in 4 levels (application of humic acid, salicylic acid, humic + salicylic acid and no application). The results of variance analysis showed that irrigation significantly affected traits of physiological, seed yield components and yield but humic acid and salicylic acid application significantly affected chlorophyle index, stomatal conductivity, 1000-seed weight and seed yield. Also, interaction effect of irrigation and humic acid and salicylic acid was no significant on measured traits. Chlorophyle index, stomatal conductivity, ear number per m2, row number per ear, seed number per row, seed number per ear and 1000-seed weight significantly decreased by 15.6, 35.6, 41.2, 14.1, 33.9, 61.8 and 40%, respectively with the decreas of water requirement from 100 to 33%. Seed yield and biological yield in treatment of 100% water requirement supply, had significantly superiority 3.9 and 2.4 times, respectively as compared with treatment of 33% water requirement supply. Chlorophyle index by 7.5, 7.7 and 8.9%, 1000-seed weight by 22.5, 26.6 and 20.7% and seed yield by 26.5, 18.5 and 21.7%, significantly increased with application of humic acid, salicylic acid and humic acid + salicylic acid respectively as compaed with no application of this acids. The results showed that supply of 100% water requirement and independent application of humic acid or salicylic acid can increase seed yield of corn.