Supplemental irrigation affected flag leaves senescence post-anthesis and grain yield of winter wheat in the Huang-Huai-Hai Plain of China

- Optimized supplemental irrigation (SI) affected the senescence of flag leaves post-anthesis.
- SI in the 0 to 40 cm soil layers (D40) increased activities of antioxidant enzyme.
- The greatest grain filling rate post-anthesis was obtained in D40 treatment.
- Optimized SI increased grain yield and harvest index of winter wheat.

In the semi-arid region in China, supplemental irrigation (SI) is a popular agricultural saving-water regime for winter wheat (Triticum aestivum L.). However, the shortage of water resources has become increasingly serious in this region. Thus, we aimed to investigate the effects of optimizing supplemental irrigation based on water content measurement in various soil layers on flag leaves senescence post-anthesis and grain yield in winter wheat under field conditions. Soil water content (SWC), measured in three soil layers i.e. 0 to 20 cm (D20), 0 to 40 cm (D40) and 0 to 60 cm (D60) prior to SI, was raised to 70% of field capacity at jointing and anthesis. The rainfed (R-F) condition was the control treatment. Results showed that the highest post-anthesis sucrose concentrations and sucrose phosphate synthase activity in flag leaves were obtained in D40, followed by D60 and D20. Water potential and flag leaves area were higher in the D40 treatment after anthesis than in the other treatments. Compared with the D20 and D60, the D40 treatment resulted in higher activities of superoxide dismutase and catalase in flag leaves from 7 to 28 days after anthesis (DAA), and lower malondiadehyde concentration from 14 DAA to 28 DAA. Moreover, the highest yield was obtain in D40 with 9.6 t ha−1 in 2011 to 2012 and 10.0 t ha−1 in 2012 to 2013, respectively, due to increasing grain filling rate and harvest index under the positive physiological basis. Moreover, comparing to R-F and D60, the water use efficiency of D40 increased. Hence, optimizing supplemental irrigation, raising SWC in the 0 to 40 cm soil layers to 70% of field capacity at jointing and anthesis (D40 treatment), could increase the grain yield and water use efficiency of winter wheat in the Huang-Huai-Hai Plain of China.