束生刚毛藻脱水和复水过程中光合作用的变化

Photosynthetic performance of Cladophora fascicularis during its dehydration and rehydration.

利用叶绿素荧光技术研究了束生刚毛藻(Cladophora fascicularis)在脱水和复水过程中光合作用的变化。自然干燥状态下,束生刚毛藻迅速脱水,干燥2.5 h后,脱水达90%。脱水1.5 h内,光合作用的最大量子产量Fv/Fm和最大相对电子传递速率Pm分别下降了约10%和11%;此后Fv/Fm和Pm的下降速度明显加快,脱水2.5 h后,已下降到初始值的一半。脱水后半饱和光强Ik逐渐下降;初始斜率α在脱水初始阶段有轻微上升,此后逐渐下降。复水后Fv/Fm、Pm、Ik和α均迅速恢复。这表明脱水可引起束生刚毛藻光合作用的降低,但光合器官并未受到不可逆损伤,因此复水后光合活性迅速恢复。这种复水后光合能力的快速恢复,有利于束生刚毛藻适应潮间带特殊的生活环境。

By the method of chlorophyll fluorescence measurement, this paper studied the photosynthetic performance of Cladophora fascicularis （Chlorophyta）during its sustained dehydration and rehydration. The results showed that after taken out from water and exposed to air, the water content in C. fascicularis cells decreased quickly, with about 90 % water loss after 2.5 h. After 1.5 h dehydration, the maximal quantum yield of photosynthesis （Fv/Fm） and the maximal relative electron transport rate （Pm） only decreased by 10 % and 11%, respectively, and after 2.5 h dehydration, both of them decreased by about half of their initial values. During dehydration, the light intensity responding to half maximal photosynthetic rate （ Ik ） decreased, while the initial rate a had a slight increase at the beginning, followed by a decrease. After 0.5 h rehydration, both Fv/Fm and Pm recovered quickly. Dehydration could reduce photosynthetic quantum yield significantly, with photosynthetic apparatus not damaged irreversibly, which made the photosynthetic activity quickly recover after rehydration. This character should be helpful to C. fascicularis to adapt the water stress in intertidal zone.