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采用培育55d的银新杨、白榆和文冠果营养钵苗在生长季6月、7月和8月不同时间进行造林,测定缓苗期3个树种叶片的光合指标,以期为幼苗缓苗期的管理提供依据。结果表明:3个树种的光合指标均存在显著差异。同一树种不同造林时间的净光合速率无显著差异,蒸腾速率、气孔导度、胞间CO2浓度则存在差异,以7月的值最大。3个树种在不同造林时间的光合特性变化基本一致,净光合速率、蒸腾速率、气孔导度与胞间CO2浓度在栽后1~3d出现持续下降,4d开始回升,5~7d内恢复到栽前水平。3个树种在不同造林时间的缓苗期为5~7d,此时应该加强土壤水分的管理,保证水分供应充足,确保幼苗尽快度过缓苗期,提高造林成活率。
Using the cultivating 55d Silver New Poplar, Ulmus pumila and Mansheng Crown seedling seedlings in different seasons in the growing season in June, July and August, the photosynthetic indexes of the leaves of the three tree species in the mitigating stage were determined, Provide the basis for the management. The results showed that there were significant differences in photosynthetic indexes among the three species. There was no significant difference in net photosynthetic rate among different afforestation time in the same tree species. There were differences in transpiration rate, stomatal conductance and intercellular CO2 concentration, with the maximum in July. The changes of photosynthetic characteristics of three tree species at different afforestation time were basically the same. The net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration decreased continuously from 1 day to 3 days after transplanting, and began to rise on the 4th day and returned to planted within 5 to 7 days Before the level. The seedling age of three tree species in different afforestation time ranged from 5 to 7 days. At this time, the management of soil moisture should be strengthened to ensure sufficient water supply and to ensure that the seedling will pass the hibernation stage and improve the survival rate of afforestation.