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毛竹(Phyllostachys pubescens)叶光合作用的气孔限制研究
STUDIES ON STOMATAL LIMITATION OF PHOTOSYNTHESIS IN THE BAMBOO (Phyllostachys pubescens) LEAVES
【摘要】 运用Farquhar和Sharkey(1982)提出的两个判据——细胞间隙CO2浓度(Ci)和气孔限制值(Ls),从几个不同的侧面研究了毛竹光合作用的气孔限制。虽然观测到气孔导度(Gs)与光合速率(Pn)随着气温、光量子通量密度的降低和叶水分胁迫的加剧而大体上平行地下降,但是在低的环境温度、低的光量子通量密度和严重的水分胁迫下,气孔导度的下降不是光合速率下降的主要原因,因为这时Ci在上升,而Ls下降。然而,在低的空气湿度和轻微水分胁迫下,Ci的下降和Ls的上升都证明,这时气孔导度的下降是光合速率降低的主要原因。
【Abstract】 Net photosynthetic rate (Pn) measurements were made on the leaves of Phyl-lostachys pubescens using an ADC portable gas analysis system under differentcombinations of air temperature, photon flux density (PFD), air humidity andleaf water potential. Analysis of stomatal limitation of photosynthesis was carriedout with two criteria suggested by Farquhar and Sharkey (1982), i.e., intercellularCO2 concentration (Ci) and stomatal limiting value (Ls), which were,calculatedaccording to Berry and Downton’s method (1982).When air temperature was decreasing from autumn to winter, Pn, stomatalconductance (Gs) and Ls were declining simultaneously, while Ci was increasing.The seasonal changes in these parameters indicated that the decrease in Pn maynot be due to stomatal factor.As air humidity decreased, Pn and Gd declined proportionally, and in themeantime Ci decreased and Ls increased, showing that the decrease in Pn wasdue mainly to the decrease in stomatal conductance.At low PFD the decrease in Pn was accompanied by a decrease in Gs and Ls,and an increase in Ci. In this case Pn was limited obviously by energy supplyrather than by CO2 supply.Leaf Pn and Gs declined sharply after detachment. At first, while waterstress was developing, Ci declined and Ls increased. However, as the water stressbecame severe, Ci began to increase and Ls decreased. It seems that stomatalclosure is the major limiting factor of Pn under mild water stress, but under severewater stress the main limitation of photosynthesis is in the photosynthetic capacityof mesophyll cells.From these results, we conclude that stomatal conductance limits Pn in somecases. However, it is not always the predominant limiting factor of photosynthesisthough parallel changes in Pn and Gs are often observed.
【Key words】 net photosynthetic rate(P_n); stomatal conductance (G_s); intercellular CO2 concentration (Gi); stomatal limiting value (L_s);
- 【文献出处】 植物生理学报 , 编辑部邮箱 ,1987年02期
- 【被引频次】194
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