Impact of deficit irrigation strategies on winter wheat in semi-arid climate of sindh

The scarcity of water for agriculture in arid and semi-arid regions increases the need for technologies to improve water use efficiency and also discover some means to increase the production from less and more reliable access to water. This research was conducted during 2017–18 and 2018–19 to assess the effect of deficit irrigation (DI), applied at appropriate critical growth stages of winter wheat (Triticum aestivum L.) by reducing 50 % of the water applied in control. The treatments were scheduled as, T1 = 100 % irrigation at all six growth stages (Ick 100), T2 = 50 % deficit irrigation at the initiation stage of the crown root (ICRS50), T3 50 % deficit irrigation at tillering stage (ITS 50), T4 = 50 % deficit irrigation at booting stage (IBS50), T5 = 50 % deficit irrigation at the heading stage (IHS 50), T6 = 50 % deficit irrigation at milky stage (IMS50), T7 = 50 % deficit irrigation at grain maturity stage (IGMS50). The highest grain yield (4558.8 kg ha−1) was achieved with full irrigation treatment Ick100. The statistical analysis conferred a significant change (p < 0.05) of deficit irrigation on grain yield, above- ground biomass, water use efficiency, plant height, spike length, grain number spike-1 and grain weight Spike-1. The maximum (17 %) reduction in grain yield was observed at the tillering stage of wheat crop when DI was applied at this stage. The IGMS50 treatment achieved 98.5 % yield with higher water use efficiency and produced almost similar grain yield to Ick100 treatment. The tillering stage (42 days after sowing) has identified as the hypersensitive and critical growth stage of the wheat crop for attaining higher yield and water use efficiency. It is recommended that water deficiency should be avoided at least at the tillering stage. However, this study concluded that 50 % water deficit at the grain maturity stage, can be an effective irrigation strategy to improve the WUE with very less yield reduction and can be implemented under semi-arid climatic conditions of Sindh and elsewhere.