长白山不同海拔岳桦(Betula ermanii)的光合生理

通过研究不同海拔(1 750 m,1 900 m,2 000 m)岳桦的光合生理,探讨岳桦叶片对高山环境的适应特征.结果表明:与海拔1 750 m相比,1 900 m和2 000 m处植物叶片具有较低的暗呼吸速率(Rd)、光补偿点(LCP)和CO2补偿点(CCP),较高的最大光合速率(Amax)、光近饱和点(LK)、表观羧化速率(CE)、最大羧化速率(Vcmax)和最大电子传递速率(Jmax).1 900 m处光化学淬灭系数(qP)和作用光存在时PSⅡ实际光化学量子效率(ФpsⅡ)最高,2 000 m处非光化学淬灭系数(NPQ)则最高.随海拔升高,岳桦叶片水分利用效率(WUE)先升高再降低.与1 750 m相比,1 900和2 000 m处植物叶片具有较高的气孔导度(gs)和CO2吸收速率(Pn/Ci斜率).分析表明:1 900 m是岳桦的最适生长区,具有较高的光合能力,且所受胁迫较小.图6表3参26

Photosynthetic Physiology of Betula ermanii Along the Altitudes in Changbai Mountains, China

The photosynthetic physiology of Betula ermanii along the altitudes in the Changbai Mountains,China was measured in order to reveal the properties of B.ermanii leaves adapting to alpine environment.The results indicated that the dark respiratory rate(Rd),light compensation point(LCP) and CO2 compensation point(CCP) at 1 900 m and 2 000 m were lower than those at 1 750 m,while the light-saturated photosynthesis(Pmax),light saturation estimate(LK),carboxylation efficiency(CE),maximum rate of RuBP carboxylation(Vcmax) and maximum rate of electron transport(Jmax) were higher than those at 1 750 m.The rates of PSⅡ electronic transmission and photosynthetic were the highest at 1 900 m,and the NPQ(nonphotochemical quenching) increased along the elevation.In addition,the WUE(water use efficiency) increased at first and then decreased,gs and efficiency of CO2 uptake(slope of Pn/Ci) were higher at 1 900 m and 2 000 m than at 1 750 m,respectively.It was concluded that physiological conditions and stress varied along the altitudes,with the altitude around 1 900 m as the best zone for growth of B.ermanii,because the photosynthetic capacity was higher in 1 900 m,while the stress was lower.Fig 6,Tab 3,Ref 26