施氮方式对玉米-大豆套作体系中作物产量及玉米籽粒灌浆特性的影响

Effect of Nitrogen Application Methods on Crop Yield and Grain Filling Characteristics of Maize in Maize-Soybean Relay Strip Intercropping System

氮肥的过量施用和低效利用，造成资源浪费和环境污染，不利于农业的可持续发展。为了减少氮肥的投入量，发挥氮肥的增产效益，本研究对玉米-大豆套作模式的施氮量和施肥距离进行优化调整。通过两年田间试验，探讨了减氮36%（RN36%）、减氮18%（RN18%）和习惯施氮（CN）3种施氮水平和距离窄行玉米0 cm （D1）、15 cm （D2）、30 cm （D3）、45 cm （D4）4种施肥距离对作物产量和玉米花后干物质积累与转运、籽粒灌浆特征的影响。结果表明，与习惯施氮相比，减氮18%处理的玉米花后干物质转移量、转移率及对籽粒的贡献率分别提高了22.65%、18.75%和15.90%，籽粒平均灌浆速率和最大灌浆速率提高了9.79%和10.76%；玉米、大豆产量及系统周年产量提高了4.95%、7.07%和5.35%；各施肥距离间，以距离窄行玉米15-30 cm的施肥效果最佳。减氮18%时， D2处理下玉米的平均灌浆速率、最大灌浆速率、穗粒数及百粒重比玉米常规穴施（D1）处理分别提高了10.32%、10.92%、9.08%和4.75%；玉米、大豆产量和系统总产最高。玉米-大豆套作体系下，减氮18%和距离窄行玉米15-30 cm施肥有利于增加玉米花后干物质的积累，促进干物质向籽粒中转运，增大灌浆速率，增加百粒重和穗粒数，提高玉米产量和大豆产量，以实现系统周年作物增产。

Nitrogen fertilizer overused and low use efficiency in agricultural system leads to wasting resources and environment pollution, which is unfavorable for the sustainable agricultural production. In order to improve the nitrogen use efficiency in maize-soybean intercropping system, a two-year field experiment was conducted to investigate the effect of different N application rates and distances on dry matter accumulation and translocation during post-anthesis and grain filling of maize, and the total crop yield in maize-soybean relay strip intercropping system. The experiment included three N application rates [210, 270, and 330 kg N ha^–1, which represent reduced 36%（RN36%）, 18%（RN18%）, and conventional N application amount （CN） , respectively] and four fertilizer application locations [the N fertilizer was applied in the area between the maize and soybean plant rows, the distance from the fertilizer application locations to maize rows was 0 cm （D1）, 15 cm （D2）, 30 cm （D3）, and 45 cm （D4）, respectively]. The results showed that, compared with CN, dry matter translocation amount and rate, and its contribution to grain yield during maize post-anthesis in the RN18%treatment increased by 22.65%, 18.75%, and 15.90%, respectively, the average filling rate and the maximal filling rate of maize increased by 9.79%and 10.76%, the grain yield of maize, soybean and total crop yield in the maize-soybean relay strip intercropping system increased by 4.95%, 7.07%, and 5.35%, respectively. The fertilizer application locations significantly affected the dry matter accumulation and contribution to grain yield during maize post-anthesis. The fertilizer effect was optimal when the fertilizer application distance was between 15 and 30 cm. With the reduced 18%N application, the average filling rate, the maximal filling rate, grain number per spike and 100-kernel weight of maize in the treatment of D2 were increased by 10.32%, 10.92%, 9.08%, and 4.75%, respectively, compared with the treatment of D1. The maximal grain yields of maize and soybean in this maize-soybean relay strip intercropping system were observed in the treatment of RN18% and D2. It is concluded that reduced N application rate （RN18%） and properly N application locations （15–30 cm to maize row） could promote the dry matter accumulation and translocation during maize post-anthesis, increase the maize grain filling rate, grain number per spike and 100-kernel weight, which could further improve the total grain yield of maize and soybean in this intercropping system.