短期施水对长期干旱铁杆蒿光合作用和叶绿素荧光特征的影响

模拟长期干旱条件下的突然降雨,研究短期施水对长期干旱条件下铁杆蒿(Artemisia sacrorum)光合特性的影响。结果表明,施水后,铁杆蒿的叶水势得到恢复,表观量子效率、羧化速率和最大光合能力明显增加,限制光合作用的气孔因素和非气孔因素得到缓解;铁杆蒿的光化学活性(Fv/Fm)在施水后完全恢复,实际光量子产量(PhiPSII))增加,PSII的还原比例和非化学猝灭(NPQ)降低;不同水分条件下,铁杆蒿叶片的叶绿素荧光光诱导过程存在较大的差异;施水后叶片光合速率(Pn)、气孔导度(gs)和PhiPSII上升速率明显加快,而非化学猝灭(NPQ)启动速度和最大值相对较小。

Effect of Short-Term Watering on Photosynthetic Characteristics and Chlorophyll Fluorescence of Artemisia sacrorum under Long-Term Drought

Water availability is an important factor affecting plant growth and yield,especially in the arid and semi-arid regions where plants are often subjected to periods of drought.Summer rains are important for most plants of semi-arid regions.A further understanding of the utilization of rain by plants requires information on responses of gas exchange and chlorophyll fluorescence to rainfall.In the present research,the effect of short-term watering after long-term drought on the photosynthetic characteristics of Artemisia sacrorum was studied by simulating a rainfall after extreme drought.The results indicated that,after watering,the leaf water potential recovered significantly,with increases in RuBP Case/Oase.Light saturation point(LSP),apparent quantum yield of photosynthesis(AQY),carboxylation efficiency(CE),and maximum photosynthetic rate with light and CO_2 saturating(Amax) were also higher in leaves of watered plants than those under continuing drought.The stomatal limitation and non-stomatal constrains to photosysthesis were relieved in A.sacrorum leaves after watering.Meanwhile,conversion efficiency of primary light energy(Fv/Fm) of PSII recovered completely after short-term watering,while the quantum yield of PSII electron transport(PhiPSII) increased significantly and the non-photochemical quenching coefficient(NPQ) notably declined.With different water conditions,the light induction processes of the plant leaves differed markedly.Net photosynthetic rate(Pn),stomatal conductance(gs),and actual PSII efficiency(PhiPSII) of watered leaves increased to maximal levels in a short period,whereas it took much longer for the water stressed leaves to reach any maximal levels.