人为去叶对紫椴幼树叶片净光合速率的影响

Effect of Artificial Defoliation on Leaf Net Photosynthetic Rate of Tilia amurensis Young Trees

采用Li—6400便携式光合作用分析系统,分析人为去叶对紫椴(Tilia amurensisRurp.)幼树净光合速率的影响。结果表明:处理树和对照树叶片净光合速率日变化趋势相同,均为单峰或双峰曲线。通过与对照树、摘叶前的处理树相比,处理树净光合速率上升变化率在摘叶强度50%的第三天、摘叶强度80%的第一、二天出现第一个、第二个峰值,说明紫椴在50%、80%去叶强度下,出现明显补偿性反应。对于处理树和对照树,影响其净光合速率的因子主要为胞间CO2浓度、光合有效辐射、叶面温度和水汽压差;变异贡献率分别在62%～99%、70%～98%之间。

An experiment was conducted to study the leaf net photosynthetic characteristics of field-grown Tilia amurensis saplings which were artificially defoliated using a Li-6400 portable photosynthesis system. Results showed that diurnal course of leaf net photosynthetic rate for both defoliated T. amurensis saplings under different defoliation intensities （30% , 40% , 50% , 60% , 70% and 80% ） and undefoliated saplings （control） presented single-peaked or double-peaked patterns during the experiment period. Compared with the control, the first and second peaks of net photosynthetic rate of T. amurensis leaves were found on the third day after the saplings were defoliated at defoliation intensity of 50% and on the first and second . days at defoliation intensity of 80%. It is suggested that the defoliated saplings have the ability to compensate for leaf area loss. The main factors influencing the diurnal change of leaf net photosynthetic rate of both defoliated and undefoliated saplings were intercellular CO2 concentration, photosynthetically active radiation, leaf temperature, and vapor pressure deficit, which could explain 62% -99% and 70% ~ 98% of the variation of leaf net photosynthetic rate of both defoliated and undefoliated saplings, respectively.