Effect of methanol spraying on some quantitative and qualitative traits of soybean under drought stress condition

In order to evaluate the effects of drought stress and methanol foliar application on some quantitative and qualitative traits of soybean (cv. Viliamz), a split plot experiment was conducted based on randomized complete block design at the Faculty of Moghan Research Farm in 2011. Treatments were three levels of drought stress based on irrigation at depletion of 40, 55 and 70 percent of available soil moisture comprising the main-plot and four rates of methanol foliar application including non-methanol spraying (control), 7, 21 and 35 volumetric percentages as sub-plots that were applied with three replications. Drought stress significantly affected stem diameter, pod length, number of seed per pod, number of pod per plant, seed yield, HI, soluble carbohydrates, chlorophyll content, oil and protein percentage of seed. Drought stress increased soluble carbohydrates and oil percentage of seed and decreased other traits, so that irrigation at depletion of 70 percent of available soil moisture decreased seed yield by 33.87 percent. Methanol foliar application significantly affected number of pod per plant, seed yield, chlorophyll content, pod length, number of seed per pods, soluble carbohydrates and seed protein content. The greatest effect of methanol foliar application on studied traits obtained from 21 percent by volume of methanol and increased seed yield by 25.6 percent in comparison with the control and the highest seed yield for irrigation after 40 percent depletion of available moisture was obtained.