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| Effect of short-term watering on photosynthetic characteristic and chlorophyll fluorescence of Stipa bungeana |
| Hu Xiangming1,2,Cheng Jimin1,Wan Hui'e1,Zhao Yanyun1,2,Xu Xuanbin1,Li Pengyuan3 |
| 1.Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Northwestern Sci-Tech University of Agriculture and Forestry,712100,Yangling,Shaanxi; 2.Graduate School of Chinese Academy of Sciences,100039,Beijing; 3.Northwestern Sci-Tech University of Agriculture and Forestry,712100,Yangling,Shaanxi: China |
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Abstract 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(Amax) 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（Fv/Fm） 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（Pn）,stomata conductance（gs）,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.
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Received: 09 November 2005
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