Deficit irrigation and sowing date as strategies to maximize water use efficiency and crop water productivity in semi-arid region

Deficit irrigation has been widely investigated as a valuable and sustainable production strategy in dry regions. In this research, different irrigation regimes and different sowing date were applied in an experimental field at southwest of Iran (semi-arid region) during 2011/2012 and 2012/2013 to identify suitable sowing date and optimum deficit irrigation for winter barley. The experiment was laid out as a split plot design, with irrigation factor as main plots and sowing date as sub-plots having three replications. Irrigation levels were 1 (FI), 0.75 (0.75FI) and 0.5 (0.5FI) times of the full irrigation requirements and dry land farming (dry land). The sowing dates were 23 October (T1), 6 and 22 November (T2 & T3) and 6 December (T4).The results showed that decreasing irrigation regimes, increased WUE in the first (0.82, 0.83 and 0.84 kg m super( -3) regularly for FI, 0.75FI and 0.5FI) and second year (0.70, 0.71 and 0.72 kg m super( -3) regularly for FI, 0.75FI and 0.5FI), but the differences between these regimes were not significant.