不同光照强度下花魔芋（Amorphophallus konjac）与谢君魔芋（Amorphophallus xiei）光合特性及光保护机制研究

为探讨不同耐光性植物光合特性及光保护机制，本研究以耐高光的喜阴植物花魔芋（Amorphophallus konjac K.Coch）和典型的喜阴植物谢君魔芋（Amorphophallus xiei H.Li & Z.L.Dao）为材料，测定与分析在透光率为100%、15%及2%光照条件下两种魔芋的光合能力、抗氧化酶活性及抗氧化物和光合色素组分的含量。结果表明，花魔芋最大光合速率和气孔导度随着生长环境光照强度降低而显著降低（P<0.05），谢君魔芋在透光率为15%时最大光合速率达最大值。大部分情况下，花魔芋的超氧化物歧化酶、抗坏血酸过氧化物酶、过氧化氢酶、谷胱甘肽还原酶活性比谢君魔芋高（P<0.05），而谢君魔芋具有较高的过氧化物酶活性（P<0.05）。总的来看，在中高光照环境下两种植物的抗氧化酶活性较高（P<0.05）。在透光率15%时，花魔芋谷胱甘肽和抗坏血酸显著比谢君魔芋高（P<0.05）。谢君魔芋的光合色素含量在透光率为15%时最高（P<0.05）；相应地，花魔芋的光合色素含量在透光率为2%时含量最低（P<0.05）；在不同光照强度下花魔芋光合色素含量基本上显著高于谢君魔芋（P<0.01）。本研究结果暗示，喜阴植物花魔芋耐受高光可能源于相对较高的光合作用能力和有效的光保护机制。

Photosynthesis and Photorotection in Amorphophallus konjac and Amorphophallus xiei Grown at a Light Gradient

To examine photosynthetic characteristics and photoprotection in Amorphophallus konjac K.Coch (AK), which is a shade-tolerant species but can grow under high light, and A.xiei H.Li & Z.L.Dao (AX), which is a shade-demanding species and can not tolerate high light, the photosynthetic capacity, antioxidant enzymes, antioxidant metabolites and photosynthetic pigments were analyzed in these two species grown under 100%, 15%, and 2.0% of full sunlight. Maximum photosynthetic rate (A_max) and stomatal conductance in AK decreased with decreasing light levels (P<0.05); however, A_max in AX reached a maximum value under 15% of full sunlight. In most cases, the activities of SOD, APX, CAT and GR were higher in AK (P<0.05); correspondingly, the activity of POD was higher in AX (P<0.05). Moreover, the activities of antioxidant enzyme were higher under high and moderate lights than under low light (P<0.05). Under 15% of full sunlight, the higher contents of glutathione and ascorbic acid were observed in AK. The content of photosynthetic pigments in AX reached a maximum value under 15% of full sunlight and that in AK a minimum value under 2.0% of full sunlight (P<0.05). In addition, the contents of photosynthetic pigments were generally higher in AK than AX under a light gradient (P<0.01). The results obtained here suggest that the tolerance of AK to high light might be related to the high photosynthetic capacity and the efficient photoprotection.