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以先玉335为试验材料,在37 500株/hm~2和67 500株/hm~2密度下测定不同叶位叶片的叶面积和光合有效辐射。从玉米冠层顶部到基部,叶片的光合生产能力呈单峰不对称曲线分布,最大值出现在顶4~6叶,两个密度下表现一致。不同叶位叶片的光合生产能力存在较大差别,在37 500株/hm~2和67 500株/hm~2的条件下,棒三叶(顶7~9)叶面积分别占群体的28.74%和29.11%,其光合生产能力分别占群体的29.60%和29.04%;棒三叶上部的3个叶片(顶4~6)的叶面积分别占群体的25.74%和25.12%,光合生产能力分别占群体的36.27%和40.57%;棒三叶下部的基部叶片分别占群体叶面积32.74%和35.23%,光合生产能力仅占群体的13.90%和9.79%。研究证实,由于冠层结构的不同造成冠层中光分布的差别,影响不同叶位叶片光合效率,导致其光合生产能力的差异。构建合理的群体冠层结构,不仅需要关注叶片的空间分布,更应该重视对冠层光合生产能力的分析。
The leaf area and photosynthetically active radiation of leaves at different leaf positions were measured with Xiangyu 335 as test material at 37 500 plants / hm 2 and 67 500 plants / hm 2. From the top to the base of corn canopy, the leaf photosynthetic capacity showed a unimodal asymmetric curve distribution, the maximum appeared in the top 4 to 6 leaves, the performance of the two density consistent. There was a big difference in photosynthetic capacity between leaves at different leaf positions. Under the conditions of 37 500 plants / hm 2 and 67 500 plants / hm 2, the area of leaves of Clover (top 7-9) accounted for 28.74% And 29.11%, respectively. The photosynthetic capacity accounted for 29.60% and 29.04% of the population, respectively. The leaf area of the top three leaves (top 4 ~ 6) accounted for 25.74% and 25.12% of the population, respectively. 36.27% and 40.57% of the population. The basal leaves of the lower part of the stem and clover accounted for 32.74% and 35.23% of the total leaf area of the population, respectively, and photosynthetic capacity accounted for only 13.90% and 9.79% of the population. The study confirmed that the difference in light distribution in the canopy caused by the different canopy structures affected the photosynthetic efficiency of leaves at different leaf positions and resulted in differences in their photosynthetic production capacity. Constructing a reasonable canopy structure not only needs to pay attention to the spatial distribution of leaves, but also pays attention to the analysis of the photosynthetic production capacity of the canopy.