Effects of supplemental irrigation with micro-sprinkling hoses on water distribution in soil and grain yield of winter wheat

• Micro-sprinkling hose (H) for wheat field supplemental irrigation (SI) was invented.
• Distribution uniformity of water (Cμ) increased with increasing H sprinkling angle.
• Lower Cμ is the likely cause of both high crop evapotranspiration and low grain yield.
• SI with an 80° sprinkling angle H achieved higher yield while reducing the SI amount.

The development of water-saving irrigation techniques is required for future food and ecological security in the Huang-Huai-Hai Plain of China, which suffers from severe water shortage. Field experiments were performed over two years (2010/2012) with the high-yielding winter wheat cultivar Jimai22 to examine the effects of supplemental irrigation (SI) with micro-sprinkling hoses on water distribution in soil and grain yield of winter wheat. Five irrigation treatments were tested: rainfed (T0), and irrigated with micro-sprinkling hoses with minimum sprinkling angles (i.e. the angle between the tangent of the initial water jet and the horizontal) of 35° (T1), 50° (T2), 65° (T3) and 80° (T4). The SI brought soil water content in the 0–140 cm profile to 75% field capacity (FC) at jointing and 70% FC at anthesis in 2010/2011, and 70% FC at both jointing and anthesis in 2011/2012. The distribution uniformity of irrigation water (Cμ) in soil after irrigation at jointing and anthesis was increased by increasing sprinkling angle from 35° to 80°. The increase in the soil water content in the 0–40 cm soil layer of the inter-rows decreased significantly with increasing distance from the micro-sprinkling hose in T1, T2 and T3, but there was no significant difference between inter-rows in T4. As sprinkling angle was increased from 35° to 80°, the amount of SI required (CIR), soil water consumption (ΔW) and crop evapotranspiration (ETc) decreased. The grain filling rate at the later filling stage, 1000-kernel weight, dry matter accumulation (DM), grain yield, and agronomic water use efficiency (AWUE) were significantly higher in T4 than in T1, T2 and T3. The CIR, ΔW and ETc had significant, negative, linear relationships with Cμ. However, DM, grain yield, and AWUE had significant, positive, linear relationships with Cμ with mean correlation coefficients of 0.60, 0.91 and 0.91, respectively. In this study, the optimum sprinkling angle of micro-sprinkling hoses for irrigating wheat after jointing was 80°.