Effects of nitrogen fertilizer and plant density on carbon metabolism, nitrogen metabolism and grain yield of two winter wheat varieties

Abstract

【Objective】A field study was conducted to investigate the effects of nitrogen fertilizer, plant density and its interaction on carbon metabolism, nitrogen metabolism and grain yield of winter wheat in moist clayey soil of southeastern Henan province, and to clarify the appropriate nitrogen-density treatment for winter wheat in this area, so as to provide the technical support for optimizing high yield and high efficiency cultivation of winter wheat in this area. 【Method】The treatments included two varieties (Xinhua 818 with medium tiller ability and high heading rate and Bainong 207 with high tiller ability and medium heading rate), three nitrogen rates (N0, 0; N240, 240 kg·hm-2; N360, 360 kg·hm-2) and three plant densities (M1, 225×104 plant/hm2; M2, 375×104 plant/hm2; M3, 525×104 plant/hm2) during two consecutive winter wheat growing seasons from 2018 to 2020 in moist clayey soil of southeastern Henan province. The differences of carbon metabolism (soluble sugar content; SPS activity; SS activity), nitrogen metabolism (soluble protein content; NR activity; GS activity) and yield under three-factor treatments were analyzed. 【Result】Variety, nitrogen fertilizer and density and their interactions significantly affected the carbon and nitrogen metabolism of winter wheat, and nitrogen fertilizer was the main effect that affected the yield and its components of the two winter wheat varieties. The effects of nitrogen application amount and planting density on carbon and nitrogen metabolism of the two winter wheat varieties in different growth stages were different. On the whole, the advantage of nitrogen-density regulation on carbon metabolism of the two winter wheat was mainly in the late filling stage, while the advantage on nitrogen metabolism was mainly in the middle stage of filling, during which the average increase of carbon and nitrogen metabolism indexes under M2N240 was 358.28% compared with the minimum treatment. The balance of carbon and nitrogen metabolism had a greater impact on the yield formation of winter wheat varieties with different tiller heading rates, especially in the late growth stage, which was the main physiological reason that the yield of Xinhua 818 was higher than that of Bainong 207 as a whole. In the winter wheat growing season from 2018 to 2020, the yield under treatment of M2N240 was the highest. Compared with the M1N0 treatment with the lowest yield, the average yield increases in two years under M2N240 were 96.49%. 【Conclusion】Considering the effects of variety, nitrogen fertilizer, density and their interactions on the balance of carbon-nitrogen metabolism and yield of winter wheat, the advantages of nitrogen application and planting density on the carbon-nitrogen metabolism of two winter wheat varieties were mainly reflected in the middle and late stages of filling. The M2N240 combination treatment could be used as a suitable nitrogen-density cultivation mode for winter wheat in the moist clayey soil area of southeast Henan province.