渗透胁迫对绿豆叶圆片叶绿素荧光的影响

绿豆叶圆片用0、-0．3、-0．6、-1．2、-1．8、-2．4MPa等6个渗透梯度处理24h后，其叶绿素荧光的反应表明：光系统Ⅱ的潜在量子产量(FD／Fm)和电子传递受体(QA)的库容(pool size)均随胁迫强度的增大而减小，但QA库容的下降明显比Fg／Fm的下降缓和。结合原初荧光Fo和最大荧光Fm的变化，分析认为本实验中渗透胁迫并未导致明显的光系统Ⅱ反应中心的失活或破坏。造成光系统Ⅱ潜在量子效率降低的原因主要是通过光系统Ⅱ反应中心到Ⅱ的电子传递受到阻抑。

Effects of osmoticstress on chlorophyll fluorescence in leaf discs of mungbean (Phaseolus aureus)

Leaf discs of mungbean (Phaseolus aureus Roxb.) were submitted to six osmotic treatments,I.e.,0,-0.3,-0.6,-1.2,-1.8,-2.4 Mpa,for 24 hours.After dark adaptation,randomly-selected 10 leaf discs were measured using a portable fluorometer (Handy PEA,Hansatech Instruments Ltd.,UK) in the dark room.Results showed that the potential quantum yield of PSⅡ and the pool size of PSⅡ electron transport accepters (QA) were both reduced by treatments of osmotic stress.The mild osmotic treatments of -0.3 and -0.6 Mpa had smaller,while moderate and severe treatments had larger influence.Associated with the Fo and Fm values in all treatments,it was suggested that osmotic stress had slight effects on the pool size of QA and did not induce the apparent inactivation or damage to PSⅡ reaction centers.The main reason for the reduced potential quantum yield of PSⅡ (Fv/Fm) was the blocking of electron transport from PSⅡ reaction center to QA.