低磷胁迫对雷公藤幼苗光合特性的影响

采用土培的方法，研究了6个浓度的磷胁迫对雷公藤1和3年生幼苗一个生长季内叶片的净光合速率（ Pn ）、蒸腾速率（ Tr ）、气孔导度（ Gs ）、胞间CO2浓度（ Ci ）和叶绿素含量（ Chl）等光合生理指标的影响。结果表明：不同程度低磷处理对1和3年生雷公藤Pn、 Tr、 Gs、 Ci 和Chl影响差异显著（P＜0．05），随着胁迫时间延长大致呈下降趋势，并随胁迫程度加重，显著降低，1年生雷公藤对低磷胁迫的响应更为灵敏，环境温度波动对雷公藤Pn、 Tr的季节变化影响大，而对3年生雷公藤叶片Chl影响较小，高温会抑制雷公藤的Pn、 Tr ，3年生雷公藤比1年生雷公藤更耐高温。雷公藤幼苗对缺磷环境有一定的调节适应能力，在轻度（20 mg· kg－1）和中度（15、10 mg· kg－1）缺磷水平的林地上可维持保证植株光合作用正常进行，而重度（5、0 mg· kg－1）缺磷条件下会对其叶片光合机构造成破坏，从而影响其生长发育，而低磷胁迫下3年生雷公藤相对于1年生雷公藤具有较好的适应能力，能够更好的适应中度和轻度缺磷的土壤条件。

Effects of low phosphorus stress on photosynthetic characteristics of Tripterygium wilfordii seedlings

Photosynthetic characters of leaf such as photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance( Gs), intercellular CO2 concentration ( Ci ) and chlorophyll content ( Chl) in one growing season under six level low phosphorus stress were investigated on Tripterygiumw ilfordii Hook.f.seedlings at different ages, one-year-old and three-year-old, in soil culture.The results showed as follows.Under low P stress , theP n , Tr , Gs , Ci and Chl of one-year-old and three-year-old T.wilfordii were gradually decreased (P<0.05), and the more low P stress, the more decreased.The response to low P stress of one-year-old T.wilfordii was more sensitive than three-year-old T.wilfordii, and followed stress time extension, the Pn of one-year-old T.wilfordii was decreased more than three-year-old T.wilfordii.The type of Pn curve of T.wilfordii leaf was double-peaked.The seasonal variation of Pn and Tr of T.wilfordii was affected by ambient temperature, but Chl was not.The Tr of T.wilfordii could be stressed at high temperature, the thermo stability of three-year-old T.wilfordii was better than one-year-old T.wilfordii.The effects of ambient temperature on the Chl of three-year-old T.wilfordii were less than one-year-old T.wilfordii.The research results showed that T.wilfordii seedlings had regulative ability for photosynthesis under mild and moderate P stress, but heavy P stress could destroy the physiology structure of T.wilfordii.The adaptation to the low P stress of three-year-old T.wilfordii was better than one-year-old T.wilfodr ii, it could be growing well under mild and moderate P stress.