采用PEG模拟干旱胁迫及复水玉米光合补偿效应

采用聚乙二醇(PEG)模拟干旱胁迫方法,研究玉米五叶期水分胁迫期间及复水后叶片叶绿素含量、叶绿素荧光动力学参数、光合参数和可溶性糖的补偿效应.研究结果表明,胁迫期间叶片叶绿素含量、PSⅡ原初光的转化效率(Fv/Fm)和PSⅡ的潜在活性(Fv/Fo)、光合速率均降低,而可溶性糖浓度升高,且降低幅度和升高幅度与胁迫程度正相关;复水后,叶片叶绿素含量、Fv/Fo和Fv/Fm、光合速率及可溶性糖浓度均逐渐恢复,出现补偿和超越补偿效应,恢复所需要时间与胁迫程度正相关.胁迫抑制植株生长,导致同化物消耗减少并在叶片内堆积,光合作用降低,表明旱后复水玉米的生长补偿与光合补偿之间具有正反馈机制.

Study on photosynthetic compensatory effects of PEG osmotic stress and rewatering on maize

Simulated water stress experiment on the five-leaf stage of maize growth with different concentrations of polyethylene glycol(PEG) in nutrient solution was performed to study the effects of water stress and rewatering on chlorophyll content,chlorophyll fluorescence kinetic parameters,photosynthetic parameters and soluble sugar content.The results indicated that the chlorophyll content,the maximum quantum yield of PS II primary photochemistry(Fv/Fm) and potential activity(Fv/Fo),and photosynthetic rate of leaves decreased,but soluble sugar content increased under water stress,and the tendency was positively related to the intensity of water stress.Meanwhile,the chlorophyll content,Fv/Fm and Fv/Fo,photosynthetic rate,and soluble sugar content gradually recovered after rewatering,resulting in compensation and overcompensation effects,and the time for recovery was positively related to the intensity of water stress.It is concluded that water stress restrains plant growth,decreases the consumption of assimilation,and leads to the accumulation of assimilation in leaves,and thus results in the decrease of photosynthetic rate.The results above suggested that there might be a positive feedback between compensatory growth and compensation of photosynthetic rate after rewatering.