Effects of Sowing Date and Single Irrigation on Yield and Yield Components of Rainfed Barley Cultivars

To study the effect of sowing date and a single irrigation (SI) on yield and yield components of barley, a field experiment was conducted in Dryland Agricultural Research Institute (Maragheh, Iran) in 2004-06 cropping seasons, using a split plot based on a randomized complete block design with 3 replications. Main plots were assigned to 3 levels of sowing date (early, normal and late). Sub-plots were assigned to five levels of single irrigation (Rainfed, 50mm SI  at planting time, 100mm SI  at planting time, SI at 50% depletion of available water and SI at 100% of depletion of available water) for two levels of sub-sub plots of barley cultivars (Abidar and Dayton (URB79-7)). The results showed the effect of planting date, single irrigation and barley cultivars on grain yield and water productivity index were significant on yield and yield components. Dayton cultivar had more yield than Abidar because of having more grains per spike and spike per square meter. Single irrigation at planting time increased grain yield by increasing seed weight, spike number per square meter and fertile spikes. Effectiveness of this treatment on average two years shows that barley yield increased up to 3500 - 4100 kg ha^-1. Limited single irrigation (SI at 50% depletion of available water) at spring time (during heading to flowering stage) had significant effects on yield and water productivity by increasing fertile spikes and seed weight.