滇青冈幼苗的光合和生长对不同生长光强的适应

Acclimation of photosynthesis and growth to different growth light conditions for seedlings of Cyclobalanopsis glaucoides

关键词:  滇青冈  光合  适应

Key words:  Cyclobalanopsis glaucoides  photosynthesis  acclimation

摘要:

研究了3种光强(全日照的80%、20%和2%)下生长的滇青冈幼苗的光合-光强响应和生长状况。结果表明:3种光强生境滇青冈幼苗光饱和点和最大净光合速率没有显著差异,20%和2%生长光强下光补偿点显著低于80%生长光强。3种光强生境幼苗的光合饱和点在400～450 μmol·m^-2·s^-1左右,光补偿点也很低(6～10 μmol·m^-2·s^-1),表现出阴生植物的特征。但滇青冈幼苗较强的耐荫能力,是以牺牲生长为代价的。在2%的弱光生境中滇青冈幼苗比叶重显著降低,单位面积和单位干重叶绿素含量均显著增多,具有利用较强辐射的潜力,一旦林窗出现就可以利用增加的辐射提高光合速率,及时进入快速高生长。

Abstract:

The response of net photosynthetic rate(Pn)to photon flux density(PFD)and the growth condition for seedlings of Cyclobalanopsis glaucoides grown under three irradiance levels(80%,20% and 2% full-light)were examined in this paper. The results showed that,there was no significant differences of the light saturation point(LSP)and the Max. net photosynthetic rate among three irradiance levels,the light compensation point(LCP)in seedlings grown under 20% and 2% full-light were decreased significantly compared with 80%. The LSP were all about 400～450 μmol·m^-2·s^-1 and the LCP were bout 6～10 μmol·m^-2·s^-1 in seedlings grown in three light levels,exhibited a characteristic of shade plant. Seedlings of C.glaucoides had a strong ability of shade-tolerance,but this adaptability is at the cost of its'reduction of growth rate and dry mass accumulation. The leaf mass per unit area(LMA)decreased and the chlorophyll content increased significantly in seedlings grown under 2% full-light,showed a great capability to taking use of high irradiance,they could grow quickly when canopy formed.