【摘要】 比较研究了两年生胡杨和灰叶胡杨叶片的光合及叶绿素荧光特性.结果表明:胡杨和灰叶胡杨均表现出净光合速率(Pn)日变化呈单峰曲线,只是在12:00时胡杨的Pn略微降低;气孔导度日变化均呈单峰型曲线;胞间CO2浓度日变化呈近“V”字型曲线.相同的试验条件下,胡杨的净光合速率、气孔导度高于灰叶胡杨,净光合速率与气孔导度峰值出现在上午10:00时;胡杨胞间CO2浓度低于灰叶胡杨,胞间CO2浓度最低值均出现在中午14:00时.经充分暗适应后的叶片叶绿素荧光参数初始荧光、PSⅡ原初光能转换效率和PSⅡ潜在活性均为胡杨显著大于灰叶胡杨.以太阳光为光化学光,测定的叶绿素荧光参数日变化显示,胡杨PSⅡ实际的光化学反应量子效率、非循环电子传递速率、光化学猝灭系数均大于灰叶胡杨,而非光化学猝灭系数却较灰叶胡杨小.胡杨与灰叶胡杨在光合与叶绿素荧光特性上的差异,是胡杨更能适应干旱荒漠区高光、高温与低相对空气湿度环境,从而表现出高净光合速率的部分生理学原因之一.更多还原

【Abstract】 The photosynthetic and chlorophyll fluorescence characteristics of Populus euphratica and P.pruinosa were comparatively studied.The results showed that the net photosynthetic rates of P.euphratica and P.pruinosa presented a single-peak curve and the Pn of P.euphratica appeared lower at 12:00;Their stomatal conductance appeared to vary in a single-peak curve and their intercellular CO₂ concentrations appeared to vary in a V-shaped curve.Under same experimental conditions,the net photosynthetic rate and stomatal conductance of P.euphratica appeared higher than those of P.pruinosa and reached their peaks at 10:00,and the intercellular CO₂ concentration of P.euphratica appeared lower than that of P.pruinosa and always reached its lowest point at 14:00.After sufficiently adapting to darkness,the chlorophyll fluorescence parameters such as Fo,Fv/Fo,and Fv/Fm of P.euphratica leaves were significantly higher than those of P.pruinosa leaves.The measurement of the daily chlorophyll fluorescence parameters with sunlight as the photochemical light indicated that the ΦPSⅡ,ETR and qP of P.euphratica were higher than those of P.pruinosa but the NPQ of the former was lower than that of the latter.It is because of these photosynthetic and chlorophyll fluorescence differences between P.euphratica and P.pruinosa that P.euphratica is more capable of adapting to the environment with strong sunshine,high temperature and low air humidity in arid and desert regions,and this is one of the physiological reasons why it has a higher net photosynthetic rate.更多还原