光强对白花兜兰光合特性及干物质积累的影响

Effects of Light Intensity on Photochemistry and Dry Weight Accumulation of Paphiopedilum emersoniii

关键词:  白花兜兰  光强  光合特性  叶绿素  生物量

Key words:  Paphiopedilum emersoniii  light intensity  photosynthetic characteristics  chlorophyll  biomass

摘要:

为探明最适宜栽培白花兜兰（Paphiopedilum emersoniii）的光强，采用人工遮阴方法研究不同光强处理（RI 10、RI 30和RI 50）对其叶片光合日变化、光响应曲线、叶绿素含量，以及地上、地下部分生物量的影响。结果表明：不同光强对白花兜兰净光合速率（Net photosythetic rate，P_n）日变化影响基本一致，P_n均随着时间递进而降低，白花兜兰叶片进行光合作用主要集中在12：00之前，不同光强处理下白花兜兰叶片P_n的降低主要是由非气孔因素导致的，气孔因素对RI 10光强处理下白花兜兰叶片P_n影响较大。RI 30光强处理下白花兜兰叶片P_n日均值最大且具有最大净光合速率 （P_max）、光饱和点（Light Saturation Point，LSP）和表观量子效率（Apparent Quantum Efficiency，AQE），显著高于其他光强处理，是白花兜兰生长的最适光强。白花兜兰为阴生植物，RI 50光强处理下白花兜兰叶片叶绿素易受损。经过2个月遮阴处理后，白花兜兰的地上和地下生物量均在RI 30光强处理下最大。因此，人工栽培白花兜兰时应进行适当遮阴处理，其最适宜栽培的光强为750 μmol·m^-2·s^-1，约为自然光强（2 500 μmol·m^-2·s^-1）的30%。

Abstract:

In order to determine the most suitable light intensity for cultivation of Paphiopedilum emersoniii, we examined the diurnal variation of photosynthesis, light response curve, chlorophyll content, aboveground and belowground biomass of leaves under different light intensity treatments (RI 10, RI 30 and RI 50) using artificial shading method.The results show that, different light intensification had the same effect on diurnal change of Net Photosythetic rate (P_n) of Paphiopedilum.P_n decreased with time.Photosynthesis in leaves of P.emersoniii mainly occurred before noon.Stomatal factors had great influence on P_n of P.emersoniii leaf under RI 10 light intensity treatment.The decrease of P_n of leaves of P.emersoniii under different light intensity treatment was mainly caused by non-stomatal factors.Stomatal factors had great influence on P_n of P.emersoniii leaf under RI 10 light intensity treatment.Under RI 30 light intensity treatment, the average daily P_n of the leaves of P.emersoniii had the maximum Net Photosynthetic Rate (P_max), Light Saturation Point (LSP) and Apparent Quantum Efficiency (AQE), which were significantly higher than other light intensity treatments, and were the most suitable light intensity for the growth of P.emersoniii.P.emersoniii is a shade plant, and the leaf chlorophyll of P.emersoniii was easily damaged under RI 50 light intensity treatment. After 2 months of shade treatment, both above and below ground biomass of P.emersoniii was maximum under RI 30 light intensity treatment.Therefore, appropriate shade treatment should be applied to the artificial cultivation of P.emersoniii.The most suitable light intensity for cultivation is 750 μmol·m^-2·s^-1, which is about 30% of the natural light intensity (2 500 μmol·m^-2·s^-1).