玉米光合生理对苗期土壤水分亏缺的响应

Response of Maize Photosynthetic Physiology to Water Deficit at Seedling Stage

在盆栽条件下研究了不同程度土壤水分亏缺下玉米苗期光合生理变化特征。结果表明:在土壤水分亏缺下,玉米叶片光合速率(Pn)、气孔导度(Gs)、蒸腾强度(Tr)均有不同程度下降,叶片水分利用效率(WUEL)有不同程度升高。轻度水分亏缺植株叶片表观光量子效率(A QY)比对照下降了6.9%,羧化效率(CE)比对照下降了26.3%,CO2补偿点(Γ)比对照升高了55.8%;重度水分亏缺处理表观光量子效率比对照下降了27.6%,玉米叶片羧化效率(CE)比对照下降了46.4%,CO2补偿点比对照升高了193.8%。土壤水分亏缺导致玉米叶片PSⅡ反应中心光化学效率(Fv/Fm)和潜在光化学效率(Fv/Fo)降低,光化学淬灭系数(qP)降低,非光化学系淬灭系数(qN)升高。轻度水分亏缺下,气孔限制是光合速率下降的主要原因;重度水分亏缺下,非气孔限制是光合速率下降的主要原因。

A pot culture experiment was used to study the variation＂ characteristics of photosynthetic physiology under different degrees water deficit of maize at seedling stage. The results showed that the net photosynthesis（Pn）, stomatal conductance（Gs）, transpiration rate（Tr）, intercellular CO2 concentration（Ci） were decreased by water deficit, but leaf water use efficiency（WUEL） got some increasing. The apparent quantum yields of photosynthesis（A QY）, car boxylation efficiency（CE） were decreased at different levels, but CO2 compensation point（ Г ） was increased by water deficit. Stomatal restriction was the main factor for Pn＇ S decrease by mild water deficit while the non-stomatal restriction was the main factor for Pn＇S decrease under severe water deficit. The Fv/Fm and Fv/Fo of PS Ⅱ of chlorophyll flu orescence were decreased by water deficit. Quenching（qP） of chlorophyll fluorescence was decreased and Non-Quenching（qP） of chlorophyll fluorescence was increased by water deficit.