玉米//花生减缓花生“氮阻遏”效应的机理研究

During the new round of structural adjustment of planting and "camber" maize area will form a substantial amount reduced period, developing maize//peanut intercropping has major significance on optimizing planting structure and regional distribution, and enhancing the efficiency of agriculture and sustainable development capacity. With the rapid development of maize//peanut intercropping, whether through researching the interspecific relationship, to form the technology system which can not only get high yield and improve the complementarity between species, but also fully exert nodule nitrogen fixation to reduce nitrogen inputs under the target of high and stable yield is a key factor. But the competition absorption of nitrogen in peanut belt and optimum amount of nitrogen during intercropping system have not been researched systematically at present. The project will be planned to explore the differences of nitrogen absorb, operation, distribution and utilization as well as peanut nodulation and nitrogen fixation capacity during compound groups at different nitrogen levels, to define the mechanism of maize on retarding peanut "N min inhibitory effect". The completion of this job can provide a theoretical basis of establishing less nitrogen and efficient production system under intercropping, and has great significance to improve the economic efficiency, ecological and social benefits of maize//peanut intercropping.

在新一轮种植结构调整和“镰刀弯”地区玉米面积将大幅调减的形式下，大力发展玉米//花生宽幅间作对优化种植结构和区域布局，提升农业的效益和可持续发展能力意义重大。随着玉米//花生粮油均衡增产模式的快速推广，在以高产稳产为目标的集约化投入条件下，能否通过研究玉米//花生体系的种间关系，形成既能高产又能提高种间互补、充分发挥根瘤固氮作用、减少氮肥投入的技术体系，是玉米//花生模式发展的关键因素。但目前关于玉米//花生体系中玉米对花生带氮素的竞争吸收以及复合群体的氮素利用还未进行系统的研究。因此，本项目拟在不同施氮水平下，探讨玉米、花生复合群体的氮素吸收、运转、分配与利用以及花生结瘤与固氮能力的差异，明确玉米对花生“氮阻遏”效应的减缓机制，为间作模式减氮高效生产体系的建立提供理论依据，对提高玉米//花生粮油均衡增产模式的经济效益、生态效益和社会效益具有重要意义。

为明确间作条件下玉米对花生“氮阻遏”效应的减缓机制，本项目在不同施氮水平下，研究了玉米、花生复合群体的氮素吸收、运转、分配与利用以及花生结瘤与固氮能力的差异。不同施氮量对土壤硝态氮含量的影响主要以表层（0-20cm）较为显著，且硝态氮存在向下层土壤迁移的趋势；各处理不同土层间土壤铵态氮含量均无显著差异。在0～225 kg/hm2范围内，随着施氮量的增加，花生产量逐渐提高。氮肥施用量在225 kg/hm2条件下，花生产量最高，为6603.26 kg/hm2，比不施用氮肥增产19.96%；达到300kg/hm2氮肥施用量时，会促进花生茎叶部的氮素积累，但同时会抑制花生根部和荚果的氮素积累，产量反而会降低。单作花生过量施用N肥会产生“氮阻遏”效应，300 kg/hm2与150 kg/hm2处理相比增产效果不显著。但是间作条件下300 kg/hm2处理靠近玉米的花生行根瘤鲜重和体积高于中行，300 kg/hm2处理中行和边行产量均显著高于150 kg/hm2处理。同时花生边行的土壤硝态氮含量显著低于花生中行，说明玉米带竞争吸收花生带的硝态氮，间作能缓解花生“氮阻遏”效应。