过量施氮对冬小麦生产力的影响

Effects of excessive nitrogen supply on productivity of winter wheat

设置0、70、140、210和280kgN·hm–25个施N梯度,对冬小麦(Triticum aestivum)旗叶光合速率(Aleaf)、群体冠层光合速率(Acanopy)、作物生长速率(CGR)和籽粒产量(GY)4个生产力水平进行综合观测研究,结果发现:在0–210kgN·hm–2区间,Aleaf、Acanopy、CGR和GY都随施N量的增大而增大;在施N量由210增加到280kgN·hm–2时,GY没有显著变化,而灌浆期Aleaf、开花期和灌浆期Acanopy、开花-成熟阶段CGR有显著减小。综合分析认为:1)过量施N(280kgN·hm–2)能显著降低灌浆期冬小麦Aleaf、Acanopy和CGR,进而抑制GY;2)过量施N对冬小麦光合生产力的抑制作用主要发生在灌浆期;3)在Aleaf、Acanopy、CGR和GY4个生产力指标中,Acanopy对过量施N的反应最敏感。

Aims Integrated research on the effect of N supply on successive levels from leaf to canopy would be helpful to improve the field N management in winter wheat production areas in China. Methods Field experiments were conducted under 5 N levels： 0, 70, 140, 210 and 280 kg N.hm-2. Four levels of productivity were measured： leaf photosynthetic rate （Aleaf） and canopy photosynthetic rate （Acanopy） measured at the stages of booting, flowering and grain-filling, crop growth rate （CGR） measured during the stages of set- ting-flowering and flowering-ripening and grain yield （GY） measured at the stage of harvesting. lmportantfindings Results show that Aleaf, Acanopy and CGR have increasing patterns at all stages when N supply increases from 0 to 210 kg N.hm-2. When N supply increases from 210 to 280 kg N＇hm2, GY has no significant variation; however, the A^af and Acanopy during the grain-filling stage and the CGR during the flowering-ripening stage decrease. These results indicate that： 1） excessive N supply of 280 kg N.hm2 can decrease the productivity of winter wheat over leaf, canopy and biomass levels and inhibit GY increasing; 2） the negative effect of excessive N supply is readily demonstrated during the stage of grain-filling; and 3） Acanopy is more capable of detecting the negative effect of excessive N supply than ＆eaf, CGR and GY.