遮荫对百山祖冷杉光合特性和叶绿素荧光参数的影响

Effect of Shade on the Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters of Abies beshanzuensis M. H. Wu.

为探索百山祖冷杉对光环境适应的生态学意义,通过模拟阳坡和阴坡光环境,研究了遮荫处理对百山祖冷杉叶片光合特性和叶绿素a荧光参数的影响。结果表明,遮荫导致百山祖冷杉净光合速率、光补偿点、光饱和点、暗呼吸速率和比叶重降低。全光下净光合速率日变化为双峰型,遮荫下正午光合速率未下降而呈平稳状态;全光下最大净光合速率和日均净光合速率高,而遮荫下光能利用率高;无论全光下还是遮荫下气孔导度与净光合速率、蒸腾速率之间均存在相似的变化趋势,且显著正相关。遮荫导致叶绿素a+b、叶绿素a、叶绿素b含量以及叶绿素a荧光参数Fv/Fm和Fv'/Fm'增加,叶绿素a/b降低。综上,百山祖冷杉是一种适应于阳生环境又具有较强耐荫性的植物,通过降低光补偿点、光饱和点、净光合速率、暗呼吸速率、比叶重以及叶绿素a/b,增加总叶绿素、叶绿素a、叶绿素b含量以及PSⅡ最大光化学效率和PSII有效光量子产量,可增强其在弱光条件下的适应能力。本研究结果为人工驯化或恢复百山祖冷杉种群选择适宜光环境奠定了基础。

This research compared the effects of full day light and shade on the photosynthetic characteristics and the chlorophyll a fluorescence parameters of Abies beshanzuensis M. H. Wu and studied the ecological significance of A.beshanzuensis on light adaptation to the environment. The results showed that the net photosynthetic rate（ Pn）,light compensation point（ LCP）,light saturation point（ LSP）,mitochondrial respiration rate in the night（ Rn） and leaf mass per area（ LMA） of the A. beshanzuensis decreased under shade condition. The diurnal variation of net photosynthetic rate（ Pn） displayed M-type and obvious ＂midday depression＂phenomenon,induced by non-stomatal limitation under full day light. The Pn levelled off around noon and no ＂midday depression＂phenomenon was observed under shade condition. The daily maximum and average of Pn decreased significantly but the efficiency of the solar energy utilization increased in shade condition compared with to full day light. The diurnal variations of Rd and stomata conductance（ Gs）in leaves were similar to Pn. Pn,Rd and Gs under full day light and shade condition showed a positive correlation to each other. The contents of chlorophyll a ＋ b,chlorophyll a and chlorophyll b in grown leaves under shade condition were significantly higher than those under full day light with the chlorophyll a / b decreased. Moreover,the ratios of Fv/Fmand F＇v/ F＇mincreased significantly under shade condition. The above results indicated that A. beshanzuensis can tolerate shade by decreasing LCP,LSP,Rd,LMA and chlorophyll a /b to increase the efficiency of the solar energy utilization,the ratios of Fv/ Fmand F＇v/ F＇m,and the contents of chlorophyll a ＋ b,chlorophyll a and chlorophyll b under shade condition. Thus,it conclude that A. beshanzuensis can survive both in sun light and shade conditions. These findings lay the foundation for the selection of the suitable light environment for the artificial domestication or restoration of the populations of the A. beshanzuensis.