种植密度对春玉米灌浆期光合特性日变化和光响应曲线及产量的影响

Light-response Curves and Yield of Maize in Grain-filling Period

为明确不同种植密度对春玉米灌浆期光合性能日变化以及产量影响的差异性,阐明春玉米灌浆中后期籽粒干物质积累、转运及籽粒产量的形成机制,为春玉米适宜种植密度的选择提供理论依据和实践指导。以春玉米品种广德5为研究对象,分析了不同密度处理对春玉米灌浆期穗位叶光合特性日变化、光响应曲线以及籽粒产量的影响。结果表明,随着密度的增加,各处理的净光合速率日变化、气孔导度日变化以及蒸腾速率日变化均呈单峰曲线变化趋势,只是达到峰值的时间存在一定差异;而各密度处理的胞间CO2浓度日变化则呈先降低后升高的“V”字形曲线变化趋势。不同种植密度的光响应曲线拟合较好,在P<0.05水平下均达到显著,最大净光合速率以M50处理最大,分别比M40、M45、M55和M60处理提高了24.28%,15.41%,18.41%,3.13%。籽粒产量以M50处理最大,分别比M40、M45、M55和M60处理高出21.60%,1.24%,0.84%,4.10%。综合各密度处理下的净光合速率、气孔导度、模拟的最大净光合速率和籽粒产量可看出,广德5适宜种植密度为M50处理(75000株/hm^2)。

In this study,the spring maize variety Guangde 5 was taken as the test material to analyze the effects of different planting densities on the diurnal variation of photosynthetic performance and yield of spring maize,and clarify the mechanism of grain dry matter accumulation,transport and grain yield formation in grain filling period,in order to provide the theoretical basis and practical guidance for selecting the suitable planting density of spring maize.The results showed that,with the increased of density,the daily variations of net photosynthetic rate,stomatal conductivity and transpiration rate all presented the unimodal curve change trends though their times to reach to the peak values were different,while the carbon dioxide concentration between the cells showed a change trend of"V"type curve.The curve fitting of photosynthetic response in different planting densities was good,reaching to a 0.05 significant level.M50 treatment had the maximum net photosynthetic rate,increasing by 24.28%,15.41%,18.41%and 3.13%,respectively,compared with M40,M45,M55 and M60 treatments.The grain yield of M50 was also the highest,which was 21.60%,1.24%,0.84%and 4.10%higher than M40,M45,M55 and M60,respectively.Considering the net photosynthetic rate,stomatal conductance,simulated maximum net photosynthetic rate and grain yield of each density comprehensively,the suitable planting density for Guangde 5 was 75 000 plants/ha.