中文摘要：

在西双版纳热带雨林条件下测定了3种热带经济植物灯台树（Alstonia scholaris）、瓜拉那（Paullinia cu-pana）和海巴戟（Morinda citrifolia）雨季和雾凉季的光合作用、叶绿素荧光、抗氧化酶活性及膜脂过氧化等指标变化.结果表明：雨季灯台树、海巴戟和瓜拉那的最大净光合速率（Amax）分别为18.9、23.2和11.7μmol·m^-2·s^-1.雾凉季3种植物的Amax、气孔导度、羧化效率和光系统Ⅱ的最大光化学效率都比雨季显著降低,并以灯台树降低的幅度最小;3种植物的非光化学焠灭（NPQ）在雾凉季比雨季都升高,其中灯台树的NPQ上升的幅度最大.雾凉季低温还导致了3种植物的抗氧化酶（CAT、SOD、APX、POD和GR）活性和丙二醛（MDA）含量都升高,并以灯台树抗氧化酶的活性更强或上升幅度最大,而MDA含量增加幅度最小.研究发现,与灯台树相比,海巴戟和瓜拉那对西双版纳雾凉季低温很敏感,雾凉季时其光合系统都受到一定程度的伤害,需要采取适当的防寒措施以缓解低温伤害.

英文摘要：

Photosynthesis, chlorophyll fluorescence, activities of antioxidant enzymes and membrane lipid peroxidation were investigated in three tropical economic tree species in a rainy season and foggy-cool season. These species are Alstonia scholaris, Paullinia cupana and Morinda citrifolia. The results showed that A. scholaris and P. cupana had higher photosynthetic capacity （A 18.9-23.2 μmol·m^-2·s^-1 ） than the other one species （11.7 μmol·m^-2·s^-1 ） in the rainy season. Amax ,stomatal conductance,carboxylation efficiency and maximum quantum yield of photosystem Ⅱ decreased significantly from the rainy season to foggy cool season. The reduced percentage in the parameters listed before was the least in A. scholaris. Non-photochemical quenching （NPQ） in all of the three species increased in foggy and cool season, with the highest increased extent in NPQ of A. scholaris. Low temperature in the foggy and cool season also led to an increase in the activities of antioxidant enzymes, i. e. , catalase, superoxidase dismutase, ascorbate peroxidase,peroxidase and glutathione reductase,and in malondialdehyde （MDA） content. In the species studied,A. scholaris had stronger activities or the highest increased percentage of antioxidant enzymes and the lowest reduced percentage of MDA content in the foggy and cool season. This indicated that A. scholaris was more tolerant to chilly temperature in the foggy and cool season than the other two species.