施水对本氏针茅光合作用和叶绿素荧光特征的影响

 通过利用短期施水代替降雨的方法,研究长期干旱条件下突然施水对本氏针茅光合特性的影响。结果表明:施水后,本氏针茅的叶水势得到恢复,RuBP羧化酶活性提高,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。同时,本氏针茅的光化学活性在施水后部分恢复,光量子产量和热耗散能力明显提高。不同水分条件下,本氏针茅叶片的叶绿素荧光光诱导过程存在较大的差异,施水条件下,叶片的光合速率、气孔导度、实际光化学效率和非光化学淬灭上升速率较快,而持续干旱条件下叶片的光诱导速率较慢。

Effect of short-term watering on photosynthetic characteristic and chlorophyll fluorescence of Stipa bungeana

Watering is an important factor affecting growth and yield of plant,mainly in 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 about（responses） of gas exchange and chlorophyll fluorescence to rainfall.In present research,the rainfall after（extreme） drought was considered to be reference;the effect of short-term（watering） after long-term drought on photosynthetic characteristics of Stipa bungeana was studied.The results indicated that,after watering,the leaf water potential recovered significantly,which resulted to RuBPCase/Oase activity increasing.Light saturation point（LSP）,apparent quantum yield of photosynthesis（AQY）,carboxylation efficiency（CE） and maximum photosynthetic rate with light and CO₂ saturating(A_max) also were higher in leaves grown short-term（watering） condition.The stomata limitation or non-stomata limitations of photosynthesis were catabatic in Stipa bungeana leaves after watering.Meanwhile,conversion efficiency of primary light energy（F_v/F_m） of PSⅡ in Stipa bungeana was partially come back after short-term watering,and the parameters of chlorophyll fluorescence such as,the quantum yield of PSⅡ electron transport（PhiPSⅡ） and the non-photochemical quenching coefficient（NPQ） were increased significantly in the short-term watering condition.Under different water conditions,the light induction processes were different significantly.Net photosynthetic rate（P_n）,stomata conductance（g_s）,actual PSⅡ efficiency（PhiPSⅡ） and non-photochemical quenching（NPQ） of watering leaves increased to maximal levels in a short period,whereas it took a much longer time for those of water stress leaves to reach maximal levels.The short-term watering Stipa bungeana leaves had a higher capacity to avoid photo-damage due to protective mechanisms,such as xanthophylls cycle-dependent dissipation of excessive energy.