PEG胁迫对玉米幼苗光合特性和叶绿素荧光参数的影响

Effect of PEG Stress on Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters of Maize Seedlings

为探讨PEG胁迫对玉米幼苗光合生理特征影响,采用水培试验对玉米杂交种郑单958幼苗以10%、15%、20%PEG进行胁迫24、48、72 h后,分别测定了叶片净光合速率(Pn)、蒸腾速率(Tr)、叶绿素荧光参数等光合生理指标。结果表明:随着PEG胁迫浓度增加,玉米幼苗叶片的、Pn、Gs与Tr均显著下降,且胁迫浓度增高以及胁迫时间延长,各指标下降幅度增大,同时基础荧光(F0)、非光化学猝灭(NPQ)呈上升趋势,最大荧光(Fm)、可变荧光(Fv)、PSⅡ潜在光化学活性(Fv/Fo)、PSⅡ最大光化学效率(Fv/Fm)和实际化学效率(φPSⅡ)呈下降趋势。但在10%和15%PEG胁迫下,玉米幼苗叶片中Fo、Fm、Fv、Fv/Fo、Fv/Fm、NPQ和φPSⅡ间均无显著差异,但与20%PEG胁迫下各指标间差异均达到显著水平。可见,随着水分胁迫程度增加,玉米幼苗叶片Pn、Tr、Gs受到抑制,其PSⅡ光能转化效率降低,热能散增加,光化学活性受到抑制,致使光合作用显著降低,影响其生长发育。

The effects of PEG stress on photosynthetic characteristics and fluorescence parameters of maize seedlings were studied in this article.The net photosynthetic rate, transpiration rate, chlorophyll fluorescence parameters of maize hybrid seedling were treated with 10%,15%,20% PEG6000 （Polyethylene glycol） stress at 3 leaf stage for 24 h,48 h,72 h,respectively.The results showed that net photosynthetic rate,stomata conductance and transpiration rate of maize seedlings leaf were decreased with the increment of PEG stress.The minimal fluorescence （Fo） and non-photochemical quenching （NPQ） increased,maximum fluorescence （Fm）,Fv,potential photochemical e^ciency（Fv/Fo）,and maximum photochemical e^ciency（Fv/Fm）,q^PS ]I decreased with PEG stress pressure increasing. However,the chlorophyll fluorescence parameters were not significantly different from that of maize seedlings under 10% and 15% PEG stress,but they were significantly different from that of maize leaf when treated with 20% PEG stress.It may be concluded that the Pn,Tr, Gs were restrained,and PS II light energy conversion efficiency,heat dissipation increased significantly and photochemical activity was inhibited with PEG stress pressure increasing,which resulted in a significant reduction of photosynthesis and affecting their growth and development.