高温干旱胁迫下香根草光合特性等生理指标的变化

Changes of Photosynthesis and Physiological Index in Vetiveria zizanioides under Heat and Drought Stress

研究了持续高温干旱胁迫条件下禾本科C4植物香根草的光合特性和几种生理指标的变化。结果表明:在整个高温干旱胁迫过程中土壤相对含水量、香根草叶片相对含水量及叶绿素含量均呈下降趋势,而丙二醛(MDA)含量和游离脯氨酸(Pro)含量持续增加,抗氧化物酶类(SOD、POD)活性先升高后降低。胁迫初期香根草叶片的净光合速率(Pn)、细胞间CO2浓度(C i)显著下降。随着胁迫程度加剧,PSII最大光化学量子产量(Fv/Fm)、PSII有效光化学量子产量(Fv’/Fm’)、光化学猝灭(qP)、非光化学猝灭(qN)、电子传递速率(ETR)下降。表明高温干旱胁迫初期光合速率的下降是由于气孔关闭引起,胁迫后期指标变化是由于叶片PSII光合系统受损引起。

This experiment used gramineous C4 plant vetiver, Vetiveria zizanioides as material to study the changes of photosynthetic characters and physiological indices under constant heat and drought stress. The results suggested that under the whole stress period, all the relative soil water content ,the relative leaf water content and the chlorophyll content showed decreasing tendencies, MDA content and dissociated proline content showed increasing tendencies, and the enzyme activity of SOD, POD in peroxide enzyme system increased at first and then decreased. Net photosynthetic rate （Pn） of vetiver＇ s leaf and intercellular CO2 concentration（Ci） decreased notably in the early period of heat and drought stress. Then notable decreases of PSⅡ max photochemistry quanta output （Fv/Fm）, PSII effective photochemistry quanta output （ Fv ＇/Fm ＇ ）, photo-chemical quenching （ qP）, electron transport rate （ETR） and non photo-chemical quenching （qN） were observed as the extent of stress increased. This suggested that the decrease of photosynthetic rate in the early period of heat and drought stress was caused by the closure of stoma, and the changes of indices in the later period of heat and drought stress was caused by the damage of PSⅡ in leaves.