作 者 ：刘悦秋,孙向阳,王勇,刘音
期 刊 ：生态学报 2007年 27卷 8期 页码：3457~3464
Keywords:Urtica dioica L. subsp. dioica, shade, photosynthetic characteristics, chlorophyll fluorescence parameters,
摘 要 ：系统研究了全光照和不同程度的遮荫（43%, 58%，73%，87%，97%）对异株荨麻光合特性和荧光参数的影响。结果表明，异株荨麻的光补偿点和光饱和点均较低，且随着遮荫程度的提高，其值以及暗呼吸速率均依次降低。净光合速率日变化曲线呈单峰型，光合速率高峰值和日平均光合速率均随着遮荫程度的提高而明显下降。蒸腾速率和气孔导度的日变化与光合速率的日变化趋势一致，遮荫对蒸腾作用和气孔导度均有显著的影响，随着遮荫程度的提高，蒸腾速率和气孔导度均显著下降。在各光照条件下，蒸腾速率与气孔导度呈显著正相关。蒸腾速率和气孔导度与光合速率的相关性随遮荫条件的不同而异，全光照条件下蒸腾速率与光合速率呈显著正相关，而所有遮荫条件下相关性不显著。气孔导度与光合速率在所有光照下相关性均不显著。各遮荫条件下叶片总叶绿素、叶绿素a、叶绿素b含量均显著高于全光照的，且随遮荫程度的提高叶绿素含量呈上升趋势，而叶绿素a/b的值则随着遮荫程度的提高而下降。叶绿素荧光参数PSⅡ内禀光能转化效率（Fv/Fm）和潜在活性（Fv/Fo）日变化呈单谷曲线。各遮荫条件下Fv/Fm和Fv/Fo值均高于全光照的，且随着遮荫程度的提高其值均依次增加。这说明，异株荨麻是一种耐荫性很强的植物，遮荫可使其降低光补偿点、光饱和点、净光合速率、暗呼吸速率以及叶绿素a/b，但增加总叶绿素、叶绿素a、叶绿素b含量、光能利用率以及PSⅡ原初光能转化效率和潜在活性，以增强在弱光条件下的生长发育能力。
Abstract:The effects of the full daylight and the different degrees ( 43%,58%,73%,87% and 97%) of the shades on the photosynthetic characters and on the chlorophyll fluorescence parameters of Urtica dioica L. subsp. dioica were examined in these observation. The results indicated that the light compensation point(LCP), light saturation point(LSP) and dark respiration rate (DP) of the Uritica dioca plant were at a low level, the value of which decreased with the increasing of shade degree. The diurnal variation of net photosynthetic rate (Pn) presented only one peak under both full daylight and all shade conditions, the daily maximum and average of net photosynthetic rate decreased significantly with increasing of shade degree, and thereby efficiency of the solar energy utilization increased. The diurnal variations of transpiration rate and stomata conductance in leaves were similar to that of net photosynthetic rate, the values of transpiration rate and stomata conductance also decreased as increasing of the shade degree. The transpiration rate and stomata conductance under full daylight and all shade conditions showed a positive correlation but did not between the transpiration rate and net photosynthetic rate under full shade condition. The stomata conductance and net photosynthetic rate also did not show a positive correlation under full daylight and all shade conditions. The content of total chlorophyll, chlorophyll a and chlorophyll b in leaves grown under all shades conditions were significant higher than those under full daylight, and increased with increasing of shade degrees, meanwhile the chlorophyll a/b decreased. Fv/Fm and Fv/Fo were significantly higher than those under full daylight and increased with increasing of shade degrees under all shade conditions. Results obtained from above showed that the shade tolerant of the stinging nettle plant was contributed by decreasing the light saturation point, light compensation point, dark respiration rate and chlorophyll a/b, through which it increased the efficiency of the solar energy utilization, the content of total chlorophyll, chlorophyll a and chlorophyll b, and the value Fv/Fm and Fv/Fo under the shade conditions.