种植密度对夏玉米碳氮代谢和氮利用率的影响

研究了低、中、高3个种植密度对夏播玉米CF008、郑单958和金海5号碳氮积累、运转及氮肥利用的影响, 以期通过密度调控碳氮代谢, 实现产量与氮肥效率协同提高。结果表明, 吐丝期茎叶总糖和全氮积累量和茎叶总糖和全氮的运转率均以中或高密度下较高, 而籽粒产量、氮素吸收效率、氮素利用效率和氮肥利用率均以中或低密度显著高于高密度。吐丝前地上部氮素积累量以中高密度下较高, 但成熟期地上部总氮量及籽粒氮量均以中低密度较高, 表明吐丝期后植株氮素积累量对玉米籽粒氮贡献较大。在中低密度下, 3个品种夏玉米产量达10 262~11 461 kg hm^-2, 氮肥利用率达23.00%~34.11%。

Carbon and Nitrogen Metabolism and Nitrogen Use Efficiency in Summer Maize under Different Planting Densities

We conducted a field experiment to obtain high yield and high recovery of N fertilizer simultaneously through regulating carbon and nitrogen metabolism under suitable planting density in 2006. The main results showed that plants grew well under low or medium densities 9.75×104 (D_1-1) and 11.25×104 (D_1-2) plants ha-1 for CF008; 8.25×10⁴ (D_2-1) and 9.75×10⁴ (D_2-2) plants ha^-1 for Zhengdan 958; and 6.75×10⁴ (D_3-1) and 8.25×10⁴ (D_3-2) plants ha^-1 for Jinhai 5]. Although C and N accumulation in stem/sheath and leaf at silking stage and C and N translocation rate were higher under medium or high density than under low density, grain yield, N uptake efficiency, N use efficiency, and recovery of N fertilizer were significantly higher under low or medium densities. N accumulation in shoots before silking was higher under medium or high density than under low density, N in shoot accumulation at maturity and N in grain were higher under low or medium density. Hence N accumulation in shoot after silking stage was important for grain N accumulation. We also obtained some quantitative criteria based on the research in Wuqiao area: for the three varieties of maize, grain yield was 10 262–11 461 kg ha^-1, recovery of N fertilizer was 23.00%–34.11% under low or medium densities.