光照强度调控4种亚热带森林植物叶片的抗氧化能力

 以亚热带林木荷树(Schima superba)和黧蒴(Castanopsis fissa)(乔木)、九节(Psycotria robra)和罗伞(Ardisia- quinguegona)(灌木)为材料，盆栽苗给予100％、36％及16％自然光照处理，同时在自然林中选择两种低光强区并采用疏伐措施使部分幼树暴露于全自然光下。在夏、冬两季采样分析叶片的抗氧化剂(AsA、GSH)含量和抗氧化酶(APX、SOD)活性，研究光强对4种亚热带树种抗氧化能力的影响。结果表明：同在自然光下，灌木的抗氧化能力较强，其AsA含量，APX．SOD活性高于乔木；随生长光强的减弱，4种幼树叶片的AsA．GSH含量和APX、SOD活性均下降，而光强改变对灌木的影响大于乔木。夏、冬季的分析结果有一定差异，说明光是自然条件下影响植物叶片抗氧化能力因子，但温度等亦有一定的作用。

THE REGULATION OF LIGHT INTENSITY ON LEAF ANTIOXIDATIVE ABILITY IN FOUR SUBTROPICAL FOREST SPECIES

The antioxidative ability of four subtropical forest plants, Schima superba , Castanopsis fissa (tree species), and Psycotria rubra,Ardisia quinguegona (shrub species) growing under different light intensities was studied. Potted seedlings were grown in three light treatments: natural sunlight (100%), and shading to 36% and 16% of natural sunlight. Young trees growing in natural forest in deep shade (8% and 3% sunlight) and at an artificially open site(sparsely cut) were also tested. Changes in the contents of ascorbic acid (AsA), glutathione (GSH) and the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD) were analyzed in leaves sampled in summer and winter. Under natural light conditions, the two shrub species showed higher antioxidative ability, with a high amount of AsA and high activities of APX, SOD relative to the tree species. The levels of AsA, GSH, APX and SOD decreased with declining light intensity in four species, but the antioxidative ability response to changing light intensity was greater in the shrub species. A close positive correlation between AsA, APX and SOD was observed across changing light intensities, indicating a good coordination of antioxidative metabolism in these woody plants. The results were somewhat different in summer and winter,showing that in addition to the important role of light intensity, other environmental factors, such as temperature may also be involved in the development and regulation of plant antioxidative ability.