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以2年生的田间‘金矮生’苹果为试材,对不同季节苹果叶片光合速率、气孔导度的日变化研究表明,“单峰型”是田间苹果叶片Pn日变化的主要类型,一天中Pn在上午8-10时达最大值,之后逐渐降低。中午过大的水蒸汽压亏缺和过高的叶温是引起Pn降低的主要因素。在大多数情况下,Gs与Pn的日变化趋势一致,但细胞间隙CO_2浓度、气孔限制值一天中变化不大,气孔对光合作用的限制较小,Pn的日变化主要取决于叶肉光合能力的变化。
The diurnal changes of photosynthetic rate and stomatal conductance of apple leaves in two seasons were studied with 2-year-old field gold dwarf apple as test material. The unimodal pattern was the main type of diurnal variation of Pn in field apple. In one day Pn reaches its maximum at 8-10 am and then gradually decreases. Noon water vapor pressure loss and excessive temperature is the main cause of Pn decreased. In most cases, the diurnal variation trend of Gs and Pn was the same, but the change of CO_2 and stomatal limitation was not obvious in one day and the stomatal limitation on photosynthesis was small. The diurnal variation of Pn mainly depended on the photosynthetic capacity of mesophyll Variety.