Zhang Shi-Bao, Hu Hong, Xu Kun, Li Zhong-Rong, Yang Yong-Ping
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China.
J Plant Physiol. 2007 May;164(5):611-20. doi: 10.1016/j.jplph.2006.02.012. Epub 2006 Apr 17.
Cypripedium guttatum can be found both in open and shady habitats. Photosynthetic acclimation of C. guttatum to different light availabilities was detected using measurements of chlorophyll fluorescence, photosynthesis and leaf traits. When growing under low light conditions, C. guttatum exhibited a greater efficiency in photochemical utilization of absorbed light energy, and a lower ability for non-photochemical dissipation of excess light energy, as compared to the plants growing under high light conditions. Under intermediate light conditions, C. guttatum exhibited higher photosynthetic capacity (A(max)) than those under both low light or high light conditions. The differences in A(max) among three light environments was linked to the differences in biochemical efficiency, leaf N content (LNC) and leaf dry mass per unit area (LMA), but not to the differences of chlorophyll content. However, there were no significant differences in the light compensation points (LCP) and light saturation points (LSP) for photosynthesis for the plants growing under the three light conditions. These results indicate that the photosynthetic capacity of C. guttatum leaves allows for flexible and reversible responses to different irradiance levels. Photosynthetic acclimation in C. guttatum was affected by biochemical changes, the changes in LMA and ratio of Chl a/b. Successful acclimation of C. guttatum to a broad range of light levels likely allows for its wide geographical distribution. A level of about 45% sunlight appears to be optimal for photosynthesis.
斑叶杓兰在开阔和阴凉的栖息地均有分布。通过测量叶绿素荧光、光合作用和叶片性状，检测了斑叶杓兰对不同光照条件的光合适应情况。与在高光条件下生长的植株相比，斑叶杓兰在低光条件下生长时，对吸收光能的光化学利用效率更高，而对过剩光能的非光化学耗散能力较低。在中等光照条件下，斑叶杓兰的光合能力（A(max)）高于在低光或高光条件下的植株。三种光照环境下A(max)的差异与生化效率、叶片氮含量（LNC）和单位面积叶片干质量（LMA）的差异有关，而与叶绿素含量的差异无关。然而，在三种光照条件下生长的植株，其光合作用的光补偿点（LCP）和光饱和点（LSP）没有显著差异。这些结果表明，斑叶杓兰叶片的光合能力能够对不同的辐照度水平做出灵活且可逆的响应。斑叶杓兰的光合适应受生化变化、LMA变化以及叶绿素a/b比值的影响。斑叶杓兰成功适应广泛的光照水平可能使其具有广泛的地理分布。约45%的阳光水平似乎最适合光合作用。
