不同灌溉处理对夏玉米氮素吸收及转移的影响

通过田间试验, 研究了两个生长季夏玉米4 个不同水分处理(灌溉1 水、灌溉2 水、灌溉3 水、灌溉4 水)对其各个生育阶段氮素吸收、分配、转移的影响。结果表明, 拔节抽雄期灌水可以增加夏玉米茎叶的氮素积累量和氮分配比, 生育后期灌水各处理之间单株氮素积累量无显著差异; 穗部的氮素积累75%来源于扬花后期氮素同化吸收, 25%来自营养器官茎叶的氮素转移, 说明灌浆至成熟期穗部氮素主要吸收利用土壤中的氮, 充足的水分可以保证营养器官积累更多的氮素, 但后期同化氮素比率随着灌水的增加而减小。因此, 灌浆至成熟期需要维持适中的水分条件, 在保证吸收利用土壤氮素的同时, 增加储存在茎叶中的氮素向籽粒的转移, 从而提高氮素利用效率。

Effect of irrigation on nitrogen uptake and translocation in summer maize

A 2-year field experiment consisting of four irrigation treatments (i.e., 1~4 irrigations during maize growth period) was carried out to study the effects of irrigation amount on the uptake, distribution and translocation of nitrogen in maize plants. The results showed that increased irrigation amount enhanced nitrogen accumulation and distribution in maize stems and leaves at jointing and tasseling stages. However, no significant differences were noted at late grain-filling stage among the different treatments. About 75% of accumulated nitrogen in maize spikes was from post-anthesis assimilation and 25% from translocated nitrogen in stems and leaves. This implied that spikes mainly absorbed N from soil during the stages of grain-filling and maturity. While abundant water supply increased N uptake in vegetative organs, it decreased post-anthesis assimilation rate. It was therefore necessary to maintain moderate water conditions to ensure not only optimum nitrogen absorption, but also increase nitrogen store in stems and leaves. The stored nitrogen would be translocated to grains, which could improve nitrogen use efficiency.