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黄淮棉区主要麦棉两熟种植方式(3∶1和3∶2 式)共生期遮荫对棉苗叶片光合性能影响的研究结果表明,棉苗叶片叶绿素含量和光合速率随叶位升高呈单峰曲线变化,其峰值叶位相同,变化趋势随遮荫程度增大而降低。与 3∶1式比较,3∶2式棉苗基部叶片叶绿素降解慢,叶绿素a/b 值增大,暗呼吸作用增强,其相应叶片有效捕捉光能的能力和生理活性提高。共生期遮荫降低了功能叶光饱和点、光补偿点和CO 饱和点,可提高叶片在较低光2强条件下对光能的捕捉能力,利于光合作用进行。与常规棉比较,麦棉共生期3∶2式遮荫对棉苗生长发育的影响较小,而 3∶1式遮荫则不利于棉苗生长发育。
The results showed that the chlorophyll content and photosynthetic rate of cotton seedling leaves increased with leaf position in the main cotton-cotton two-cropping system (3:1 and 3-2 type) in Huang-Huai cotton area. Showing a single peak curve changes, the peak leaf position is the same, the trend of change with the degree of shade decreases. Compared with the 3: 1 formula, the chlorophyll content of the basal leaves of 3: 2 cotton seedling was slowed down, the chlorophyll a / b value was increased, the dark respiration was enhanced, and the photosynthetic activity and physiological activity of its corresponding leaves were enhanced. Symptomatic shading reduced the light saturation point, light compensation point and CO saturation point of functional leaves, which could enhance the light energy capture ability of leaves under the condition of lower light intensity and facilitate the photosynthesis. Compared with the conventional cotton, the 3: 2 type of cotton symbiosis had less effect on the growth and development of cotton seedlings, while the 3: 1 type of shade was not conducive to the growth of cotton seedlings.