Effect of Water Deficit on Morphological Traits and Water Use Efficiency of Two Soybean (Glycine max L.) Cultivars

Abstract

In order to investigate the effect of water limitation on morphological traits and water use efficiency in two soybean cultivars, a split-plot experiment was conducted in 2004 at the Research Farm of the Faculty of Agriculture, University of Tabriz, Iran. Irrigation treatments ( I1, I2, I3 and I4: irrigation after 60±3, 80±3, 100±3 and 120±3 mm evaporation from class A pan, respectively) were assigned to main plots, and two soybean cultivars (Zane and Huck) were allocated to the subplots. The results indicated that the Huck required less GDD (growing-degree days) to complete the growth and developmental stages, compared with Zane. Flowering and maturity for Huck occurred about 3 days earlier than those for Zane. The mean number of branches, plant height, biological and grain yields under well watering (I1) were higher than those under limited irrigations (I2, I3 and I4). All these traits were decreased with increasing water deficit. The highest harvest index was obtained from I1 treatment, however, this superiority was not significant statistically, when compared with other irrigation treatments. Therefore, it was concluded that water use efficiency (WUE) could be improved, with decreasing irrigation. However, the volume of water at each irrigation increased and grain yield decreased, as water deficit severed. Consequently, it seems that irrigation with low volume and short intervals might be more suitable for soybean production