氮肥基追比例对测墒补灌小麦冠层不同层次光能利用及干物质转运的影响

Effects of basal/topdressing nitrogen ratio on light interception and dry matter transport at different layers of wheat canopy under supplemental irrigation based on soil moisture

【目的】研究测墒补灌节水栽培条件下,氮肥基追比例对小麦植株冠层不同层次光能利用和干物质积累转运及分配的影响,为确定合理的氮肥运筹模式提供依据。【方法】以‘济麦22’小麦为试验材料,在总施氮量为240 kg/hm^2条件下,设置5个氮肥基追比例,分别为N1 (0∶10)、N2 (3∶7)、N3 (5∶5)、N4 (7∶3)、N5(10∶0),在拔节期和开花期,土壤相对含水量均补灌至田间持水量的70%。【结果】氮肥基追比例为5∶5的N3处理开花后的叶面积指数、冠层上层和中层的光合有效辐射(PAR)截获率及截获量显著高于其它处理,中层和下层的透射率显著低于其它处理,PAR转化率和利用率较N1、N2、N4和N5分别提高13.64%、8.02%、8.70%、14.38%和21.17%、8.50%、10.67%、23.88%。N3处理开花后干物质同化量、成熟期干物质积累量及中层营养器官开花前贮藏干物质向籽粒的转运量、转运率显著高于其它处理,籽粒干物质分配量较N1、N2、N4和N5分别提高11.37%、5.68%、6.03%和16.25%。相关分析表明,中层营养器官开花前贮藏干物质向籽粒的转运量与中层PAR截获率呈显著正相关;籽粒干物质分配量与上层、中层及总PAR截获率呈显著正相关,与下层PAR截获率呈显著负相关。【结论】氮肥基追比例为5∶5的处理显著提高了小麦冠层的光能利用,促进了中层营养器官开花前贮藏干物质向籽粒的转运,获得了最高的籽粒产量,为本试验条件下的最优处理。

【Objectives】Under water-saving cultivation conditions,the effects of base application ratio of nitrogen on light energy utilization and accumulation,transport and distribution of dry matter in different layers of wheat canopy were studied to provide a basis for rational nitrogen fertilizer management.【Methods】The study included five treatments at a nitrogen application rate of 240 kg/hm^2,with fertilizer ratios of base to topdressing of 0∶10(N1),3∶7(N2),5∶5(N3),7∶3(N4)and 10∶0(N5)for the cultivar Jimai 22.Relative soil moisture content was maintained up to 70%of field capacity at the joining and anthesis stages of wheat.【Results】Leaf area index at 0,7 and 14 days after anthesis,photosynthetically active radiation(PAR)capture ratios in upper and middle layers of wheat canopy under the N3 treatment with ratio of base fertilizer to topdressing of 5∶5 were significantly higher than those under other treatments,and penetration through the middle and lower wheat canopy layers was significantly lower than that under other treatments.Compared with the N1,N2,N4 and N5 treatments,PAR conversion and utilization efficiencies of N3 were increased by 13.64%,8.02%,8.70%and 14.38%,and 21.17%,8.50%,10.67%and 23.88%,respectively.Dry matter assimilation after anthesis,dry matter accumulation at maturity,rates of dry matter translocation and transport from middle-layer vegetative organs to grains before flowering under the N3 were significantly higher than those under other treatments.Compared with the N1,N2,N4 and N5 treatments,dry matter distribution amounts in grains at maturity were increased by 11.37%,5.68%,6.03%and 16.25%,respectively.Correlation analysis showed that dry matter transport from middle-layer vegetative organs to grains before flowering was significantly and positively correlated with PAR capture ratio in the middle layer.Dry matter distribution in grains was significantly and positively correlated with PAR capture ratios in the upper,middle and all layers,and significantly and negatively correlated with PAR capture ratio in the lower layer.【Conclusions】The treatment with base to topdressing fertilizer ratio of 5:5 significantly enhanced light energy utilization in wheat canopy,promoted dry matter transport from middle-layer vegetative organs to grain before anthesis and accumulation of dry matter after anthesis,and resulted in the highest grain yield.The treatment with base to topdressing fertilizer ratio of 5:5 was the best treatment under the test conditions.