氮肥运筹对麦后直播棉光合性能、生物量、氮素累积及产量的影响

Effects of nitrogen management on photosynthesis,biomass,nitrogen accumulation and yield traits of field-seeded cotton after barley harvest

以早熟棉中棉所50为材料,采用裂区设计,研究施氮量(0 kg/hm^2、75 kg/hm^2、150 kg/hm^2、225 kg/hm^2和300 kg/hm^2)和施用次数(1次和2次)对麦后直播棉光合性能、生物量、氮素累积及产量性状的影响。结果表明,麦后直播棉功能叶SPAD值、净光合速率、生物量和氮素累积量及果枝数、果节数和节枝比均随施氮量增加而增加;功能叶SPAD值和净光合速率、果枝数、果节数和节枝比在初花期以施用1次处理较高,吐絮期则以施用2次处理较高;生物量在盛花期前以施用1次处理较高,其后以施用2次处理较高;氮素累积量初花期以施用1次处理较高,初花后以施用2次处理较高。施氮量与施用次数互作分析结果显示,吐絮期功能叶SPAD值与净光合速率、果枝数、果节数及皮棉产量均以150~300 kg/hm^2、施用2次处理较高。理论生物量和最大累积速率随施氮量的增加而增加,以施用2次处理较高,且以施氮量150 kg/hm^2、施用2次处理生物量快速累积起始期较早、持续期较短而速率较高。相关性分析结果表明,初花后氮素累积有利于提高生物量快速累积期的最大速率和最终的生物量,初花后生物量和氮素累积量与吐絮期果枝数、果节数及产量呈极显著正相关。综上所述,氮肥运筹显著影响麦后直播棉光合性能、生物量和氮素累积,以施氮量150 kg/hm^2,施用2次处理生物量累积特征值较优,有利最终产量的形成。

Using the early maturing cotton （ CCRI 50） as material,a field experiment was carried out to evaluate the effects of nitrogen management on photosynthetic characteristics,biomass,nitrogen accumulation and yield traits of field-seeded cotton after barley har^^est. A split-plot design with three replicates was used for the study. The main plots comprised five levels of nitrogen application rate （ 0 kg/hm^2 ,75 kg/hm^2 ,150 kg/hm^2 ,225 kg/hm^2 and 300 kg/hm^2）,while two levels of application frequency （one or two times） constituted the subplots. The results showed that the SPAD value and the net photosynthesis rate of functional leaves, the biomass and nitrogen accumulation,the numbers of fruit branches and fruit nodes increased increase of nitrogen rate from 0 kg./hm_ to 300 The SPADvalue and the net photosynthesis rate of functional leaves, the numbers of fruit branches and fruit nodes of one time applica-tion were higher than those of the two times application at early-flowering stage, but they were contrary at boll-opening stage. The biomass of one time application was higher than that of the two times application before full-flowering stage, but it was contrary after full-flowering stage. The nitrogen accumulation of one time application was higher than that of the two times application at early-flowering stage, but it was contrary after early-flowering stage. The results of interactive effect of nitrogen rate and application frequency showed that the SPAD value and the net photosynthesis rate of functional leaves, the number of fruit branches and fruit nodes at boll-opening stage and lint yield were higher under the treatment of nitrogen rate from 150 kg/hm^2 to 300 kg/hm^2 with two times application. The maximum biomass of rapid accumulation and its maximum speed increased with the increasing of nitrogen rate, and they were higher under the treatment of two times application than those of one time application. The biomass accumulation initiated earlier but lasted less days with higher maximum speed under the treatment of 150 kg/hm^2 nitrogen rate with two times application than those of other treatments. The results of cor-relation analysis showed that the nitrogen accumulation after early flowering was beneficial for increasing biomass accumula-tion and its maximum speed. Correlation analysis also showed that biomass and nitrogen accumulation after early flowering positively correlated with the number of fruit branches and fruit nodes and lint yield at boll-opening stage. In summary,ni- trogen management affected photosynthesis, biomass and nitrogen accumulation of field-seeded cotton after barley harvest.The higher nitrogen accumulation,more optimized characteristic value of biomass accumulation and higher yield were found under the treatment of nitrogen rate of 150 kg/hm^2 with two times application.