摘要
叶片水势(ψ)为-1.2MPa的桃金娘叶片光合速率(PN,μmol.m^(-2)S^(-1))与光强(PAR,mmol.m^(-2)s^(-1))关系曲线的最初直线部分PN=2.13+17.96 PAR,r^2=0.89。当ψ降至-2.0MPa,相当关系为PN=0.37+15.49 PAR,r^2=0.9。最大PN降低43.7％。罗伞叶片ψ从-1.06MPa降至-1.9MPa,最大PN降低69.6％,较桃金娘大。桃金娘叶片有较高气孔传导率(g,mmol.m^(-2)s^(-1))。ψ降低引起桃金娘叶片g的降低较罗伞少。叶片ψ降低使PN与细胞间CO_2浓度(Ci,μ1.1^(-1))关系曲线的直线部分斜率变小。低g和当Ci高于外界CO_2浓度时表现低羧化能力,可能是罗伞光合速率低的原因。自然林被破坏后,土壤和空气水分状况变化可能在林分更替中起作用。
Photosynthetic rate in leaves of Rhodimyrtus tomentosa decreased by 43.7% as leaf water potentential declined from -1.25 MPa to -2.0 MPa at lower light intensity. The relationship between photosynthetic rate (PN, μmol.m-2s-1) and light intensity (PAR, m mol . m-2s-1) was PN- 2.13+17.96 PAR, r2 = 0.89 in leaves of Rhodomyrtus tomentosa with leaf water potential -1.25 MPa. While the correspondencing relationship was PN = 0.37+15.49 PAR, r2 = 0.9 as leaf water potential decreased to-2.0 MPa. Ardisia quinquegona had lower photosynthetic rate and it decreased by 69.6% as leaf water potential declined from -1.06 MPa to -1.9 MPa
More of the higher stomotal conductance was presented in leaves of Rhodomyrtus tomentosa as comparied with that Ardisia quinquegona. Lower photosynthesis in leaves of Ardisia quinquegona might attribute to decreasing stomotal conductance as lower leaf water po-tential developed.
Photosynthesis decreased in leaves of these shrubs as leaf/ air water vapor gradient (△W) increased and the decrease of water use efficiency in leaves of Ardisia quinquegona with leaf water potential by -1.9 MPa as △W was higher than that of Rhodomyrtus tomentosa. The changes of water conductance in soil and atmosphere after the damage of the natural forest might induce the development of water stress in plants and it might be determine the succession of plants in forest site.
出处
《云南植物研究》
CSCD
1992年第3期307-313,共7页
Acta Botanica Yunnanica
关键词
桃金娘
罗伞
水分胁迫
光合作用
Rhodomynus tomentosa: Ardisia quinquegona
Photosynthetic rate
Water stress: Plant succession
