不同修枝处理对10年生三倍体毛白杨生长和光合特性的影响

Effects of Different Pruning Treatments on Growth and Photosynthetic Characteristics of 10-year-old Triploid Populus tomentosa

为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨树为对照,研究不同强度修枝对10年生毛白杨生长和生理特性的影响。结果表明:对于10年生中高龄杨树,修枝对树高、胸径、材积增长率无显著影响,但重度修枝能提高剩余叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s)),增强单叶水平上物质合成的能力,而修枝对瞬时水分利用效率(WUE)影响不显著。从生长和光合角度综合分析,修去树冠下部1/2枝条能够改善10年生毛白杨生理状况,但对林木生长无明显促进作用。

In order to explore the response of photosynthetic physiological characteristics to different pruning intensities in Populus of middle and high forest age,10-year-old triploid Populus tomentosa asexual lines B301 and S86 were used as materials,light pruning(pruning the lower 1/3 of the canopy)and heavy pruning(pruning the lower 1/2 of the canopy)and unpruned trees as the control were adopted respectively.The results showed that pruning had no significant effect on the growth rate of height,diameter at breast height and wood volume of 10-year-old Populus,but heavy pruning increased the net photosynthetic rate(P_(n)),transpiration rate(T_(r)),and stomatal conductance(G_(s))of their remaining leaves and enhanced material synthesis at the single-leaf level,while pruning had no significant effect on instantaneous water use efficiency(WUE).From a comprehensive analysis of growth and physiology,pruning the lower 1/2 of the canopy could improve the physiological condition of 10-year-old Populus tomentosa,but had no significant effect on the growth of the stand.