干旱胁迫对莫莫格湿地芦苇叶片光合生理生态的影响机理研究

Mechanism of Influence of Drought Stress on Photosynthetic Physiological Ecology of Phragmites australis Leaves in Momoge Wetlands

为了揭示干旱胁迫对芦苇(Phragmites australis)叶片光合生理生态的影响机理,利用LI-6400便携式光合仪和快速叶绿素荧光仪,对干旱胁迫条件下的芦苇叶片光合生理以及芦苇生长状态进行测量分析。结果表明,干旱5d后,芦苇叶片光合速率小幅下降,干旱15d后,其光合速率明显下降,芦苇生长受到显著抑制;干旱胁迫下,芦苇叶片叶绿素含量先增加后减少;芦苇叶片光系统II(PSII)对干旱胁迫反应较敏感,在干旱20d后,其光合电子传递能力和光合性能指数下降,热耗散增加。在干旱胁迫初期,芦苇叶片光合速率的下降以气孔限制为主;在干旱胁迫后期,非气孔限制与气孔限制都起作用,其中非气孔因素主要是指光系统II活性的下降,活性反应中心减少,电子传递能力下降,降低了光系统II的整体光化学性能,进而降低了芦苇叶片的光合速率,抑制了芦苇的生长。

To reveal the mechanism of influence of drought stress on the photosynthetic physiology of Phrag- mites australis leaves, the growth and photosynthetic characteristics of reed leaves exposed to drought stress were measured by LI-6400 portable photosynthesis system and chlorophyll fluorescence fluorometer. The re- sults showed that the growth of Phragmites australis was significantly inhibited after 15-day drought. The pho- tosynthesis rate （,on） of the leaves declined after 5-day drought and declined further after 15-day drought. The chlorophyll content increased after 5-day drought, but it decreased after longer-time drought. The photosystem II of the leaves was sensitive to drought stress. The electric transfer （ETJRC） and photosynthesis index （PIABs） decreased, heat dissipation （DIo/RC） increased after 20-day drought. The results suggested that the stomotal limitation is the main reason of the decrease of photosynthesis rate of the leaves after short-term drought; the non-stomotal limitation and stomotal limitation all lead to the decrease of photosynthesis rate after long-term drought. The non-stomotal limitation includes the decrease of the activity of photosystem II. The active reac- tion centers decreased, photosynthesis rate of the leaves reduced and finally the growth ofPhragmltes australis was inhibited.