干旱胁迫对杨树气体交换与荧光参数的影响

以白杨派和黑杨派杨树的盆栽苗为试材,分析了不同干旱胁迫程度对5个杨树的气体交换参数与荧光参数(Fv/Fm、Fmv/Fms)的影响,并对不同树种的耐旱性进行了综合评价。结果表明:①5种杨树净光合速率与蒸腾速率均随苗木叶水势的下降而呈明显下降趋势;在水分胁迫初期,欧洲黑杨和银白杨的净光合速率呈现明显的上升趋势。②在中度干旱胁迫前,5个供试杨树的水分利用效率大部分随叶水势的下降有增大现象。③不同树种的Fv/Fm随叶水势降低总体上呈逐渐下降趋势。④与Fv/Fm相比,Fmv/Fms能更直接地反映光合机构的实际光能捕获能力。⑤当苗木叶水势为-1.5 MPa时,5个树种耐旱性的综合评价结果为:转Bt基因欧洲黑杨>欧洲黑杨>银白杨>银灰杨为欧洲山杨,综合指数评价结果与采用单一指标中的水分利用效率完全一致,与净光合速率相近;水分利用效率证明是一种较为可靠的树种耐旱性评价指标。

Responses and Evaluation of Gas Exchange Parameters and Fluorescence Parameters of Aspen and Crossbreed to Drought Stress and Their Evaluation

Selecting Leuce Duby and Aigeiros Duby seedlings as materials, this paper analyzed the responses of gas exchange parameters(Pn、Tr、WUE) and fluorescence parameters(Fv/Fm、Fmv/Fms) of five breeds of aspen and Crossbreed to Drought Stress, and comprehensively evaluated the drought-resistant characteristics of five breeds. It was found that the net photosynthetic rate and transpiration rate of five breeds obviously descended with the descend of leaf water potentials, at the initial stage of water stress, the net photosynthetic rate of Populus nigra and P. alba showed a obvious increasing trend. Before midium drought stressing,the water using efficiency of all the five breeds all showed the phenomenon of increasing with the descending of leaf water potential, the drought-resistance characteristics maybe a regular reflection of these breeds. Fluorescence parameter Fv/Fm of different breed wholly gradually descended with the descending of leaf water potential, the value of leaf water potential at the sudden descending point of Fv/Fm might become a new index to compare the drought-resistant capacity of different breeds. Compared with Fv/Fm, fluorescence parameter Fmv/Fms could directly inflect the practical solar energy capture capacity. While the leaf water potential of seedlings -1.5 MPa, the comprehensive evaluation result of drought-resistant capacity of the five breeds were: transgenic P. nigra carried Bacillus thuringiensis (Bt) gene > P. nigra > P. alba > P.×canescens Smith, P. tremula, which was same to the result while water using efficiency was only adopted, and near to net photosynthesis rate, water using efficiency had proved to be a relatively reliable index.