干旱胁迫下４种常用植物幼苗的光合和荧光特性综合评价

卢广超 Lu Guangchao,刘斌 Liu Bin,薛立 Xue Li,邵怡若 Shao Yiruo,李诗刚 Li Shigang,许建新 Xu Jianxin

doi:10.5846/stxb201303150430

Abstract

老鸭嘴，山毛豆，假连翘和葛藤是常见的矿山植被恢复植物。采用盆栽控制土壤水分的方法，测定了这 4 种幼苗叶片的光合和荧光指标，以期为矿山植被的恢复植物筛选提供依据。结果表明（1）干旱胁迫处理期间，4 种幼苗叶片的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和胞间CO2 浓度（Ci）持续下降，复水8 d后Pn均显著增加，老鸭嘴和山毛豆的Gs和Tr恢复到对照水平，山毛豆和葛藤的Ci恢复到对照水平；假连翘幼苗叶片的气孔限制值（Ls）随干旱胁迫时间的延长而逐渐增加，其他3 种幼苗略降后增加，复水8 d后均恢复到对照水平。（2）干旱胁迫处理期间，4 种幼苗叶片的photosystemⅡ（PSⅡ）光能捕获效率（Fv’/Fm’）、实际光化学量子效率（Yield）和表观电子传递速率（ETR）持续降低，8 d时显著小于对照。复水8 d后，Fv’/Fm’小幅波动，Yield和ETR有所恢复，其中葛藤的Yield和山毛豆的ETR恢复到对照水平；4种幼苗叶片的非化学淬灭（NPQ）持续上升，在第8天显著大于对照，复水8 d后，均持续下降，其中葛藤恢复到对照水平。（3）对光合和荧光指标进行主成分分析表明，干旱胁迫下4 种幼苗的抗旱性能大小顺序为山毛豆 > 老鸭嘴 > 假连翘 > 葛藤。;With global climate change, environmental stresses will become the most important issue for plant growth. Among these environmental factors, drought is the most important factor that limits photosynthesis and growth. As a result, an advancement in the current understanding of the responses of plants to drought stress has became a major target for research. Drought limits stomatal conductance, mesophyll conductance and photosynthetic metabolism, and the possibility of overexcitation of photosystemⅡ increases, and this reduces the photosynthetic rate and lead to an increase in the dissipation of absorbed energy through nonradiative processes. Therefore, photosynthesis and chlorophyll fluorescence can greatly help the differentiation of plants and the physiological understanding of the process under drought conditions. It has been proposed that the choice of a photosynthesis and chlorophyll fluorescence parameters as an indicator of plant performance under drought stress, in order to provide a technique for rapidly screening plants with different drought tolerances. The Thunbergia erecta, Tephrosia candida, Duranta repens and Pueraria lobata are common plant species used for mine vegetation restoration. A test of potting methods with water control was applied to study the photosynthetic and fluorescence characteristics of the seedlings of four plant species for mine vegetation restoration. The results were as follows: (1) The parameters of net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and intercellular carbon dioxide concentration(Ci) of the four species decreased gradually with increasing drought time. After 8 days of rehydration, the Pn of the four seedling types greatly increased. The Gs and Tr of T. erecta and T. candida, and the Ci of T. candida and P. lobata returned to the controls level after rehydration with 8 days. The value of stomatal limits (Ls) of D. repens increased gradually with drought time, whereas that of other seedling types slightly decreased followed by an increase, and the Ls of the four seedling types returned to the controls level after 8 days of rehydration. (2) The chlorophyll fluorescence parameters of the excitation capture efficiency of PSⅡ (Fv'/Fm'), photochemical quantum yield of PSⅡ in the light (Yield) and apparent electron transport rate (ETR) of the four seedling types continuously decreased and significantly lower than the controls at 8th days after drought stress. After 8 days of rehydration, the Fv'/Fm' of the four seedling types waved slightly, their Yield and ETR recovered to some extent, but the Yield of P. lobata and the ETR of T. candida returned to the controls level. The non-photochemical quenching (NPQ) of the four seedling types continuously increased and it significantly greater than the control after 8 days of drought stress. The NPQ of P. lobata returned to the controls level, whereas that of the other seedling types decreased continuously after 8 days of rehydration. (4) The photosynthetic characteristics and chlorophyll fluorescence parameter of the four seedling types were evaluated with principal component analysis, indicating that the order of drought resistance of the four seedling types was T. candida > T. erecta > D. repens > P. lobata.

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