Abstract:

Aims Our objective was to determine the effects of irrigation schedule on grain yield, water use efficiency (WUE), and accumulation and distribution of dry matter in winter wheat (Triticum aestivum) ‘Lingkang-2’ in the arid Hexi corridor of Northwest China.

Methods Based on pre-winter irrigation quota of 180 mm, we set up five irrigation treatments, i.e., irrigation quota of 165 mm at the jointing stage (W1), irrigation quota of 120 mm at the jointing stage and 105 mm at the heading stage (W2), irrigation quota of 105 mm at the jointing, heading and grain filling stages, respectively (W3), irrigation quota of 75 mm at the jointing, heading and grain filling stages, respectively (W4), and irrigation quota of 105 mm at the jointing stage, 75 mm at the heading stage, and 45 mm at the grain filling stage (W5).

Important findings Available soil water content (AWC) in the 0-150 cm layer across different irrigation treatments changed with wheat growth stages. The grain yield in both W3 and W4 treatments was obviously improved by higher leaf area index (LAI) and dry matter accumulation. Higher AWC was found in the W3 and W4 treatments, but there was no significant difference in the grain yield between the two treatments. Nevertheless, the highest water use efficiency (WUE) in the W4 treatment was associated with its higher value of growth index than those in the W1, W2 and W5 treatments. In contrast, LAI in the W1, W2 and W5 treatments quickly decreased after anthesis, corresponding to lower dry matter accumulation, shorter grain filling duration and fewer numbers of spike and lower 1000-grain weight. We also observed that drought stress after anthesis promoted dry matter translocation from vegetative organs to grains, with a complementary effect on grain yield occurring as drought stress increased. In the grain filling stage, drought stress stimulated average filling rate, but shortened the duration of grain filling. The duration of grain filling, effective period of grain filling, the value of increases in grain weight during effective period of grain filling, and the timing of the maximum filling rate were positively correlated with 1000-grain weight and grain yield of winter wheat (p < 0.05). In consideration of all results, winter wheat should be irrigated at 75 mm at the jointing, heading and filling stages to achieve reasonable water use efficiency and grain yield. Our findings may help with the decision makers by providing hydrological and ecological evidence in development of sustainable agriculture in arid regions.

Key words: dry matter, grain filling, grain yield, irrigation, winter wheat