[Effects of water and nitrogen management on photosynthetic matter production and yield of wheat].

The shortage of water resources and the irrational application of nitrogen fertilizer restrict the synergistic enhancement of yield and water- and fertilizer-use efficiencies of wheat in the Huang-Huai-Hai region. In this study, we conducted an experiment following two-factor split zone design with three irrigation levels and four nitrogen application rates. The relative water content of the 0-40 cm soil layer was supplemented to 65% (W), 75% (W), and 85% (W) of field water capacity at the jointing and anthesis stages of wheat. The rates of nitrogen application were 0 (N), 150 (N), 180 (N), and 210 (N) kg·hm. We analyzed the effects of these different managements on post-anthesis photosynthetic matter production, yield, and water- and nitrogen-use efficiencies. The results showed that yield first increased with increases in the levels of irrigation and nitrogen application, peaking under the WN treatment (9103.53 kg·hm). However, further increases in water and nitrogen input did not have further enhancement of wheat yield. Under the same nitrogen application condition, compared with W treatment, the canopy light interception rate, chlorophyll relative content and actual photochemical efficiency after anthesis increased by 4.5%-6.0%, 19.7%-28.2%, and 7.5%-9.8% in response to the W treatment, respectively, without any difference between the W and W irrigation levels. At the same irrigation level, post-anthesis dry matter accumulation in repose to the N treatment increased by 80.1%-88.9% and 16.7%-22.2% compared with N and N treatments, respectively, without significant difference between the N and N treatments. Both the irrigation water-use efficiency (IWUE) and the nitrogen partial factor productivity declined with increases in the levels of irrigation and nitrogen application. Under the W, W, and W treatments, the values obtained for IWUE were 16.23, 11.01, and 7.91 kg·hm·m, respectively, whereas in response to the N, N, and N treatments, N partial factor productivity was 50.8%, 48.4%, and 42.5%, respectively. In all, based on soil moisture measurements and assessments of wheat yield and water- and nitrogen-use efficiencies, the optimal water and nitrogen management strategy for enhancing wheat yield in the Huang-Huai-Hai region is supplementation of water content of 0-40 cm soil layer at the jointing and anthesis stages to 75% field capacity combined with the application of 180 kg·hm nitrogen (WN). This approach could achieve high yield and efficiency and promote conservation of water and fertilizer.