盐胁迫对不同种源麻栎叶片光合特征的影响

采用5 个不同盐浓度处理，研究了盐胁迫对山东费县、安徽滁州和四川万源3个种源地麻栎叶片光合特征的影响.结果表明：随着盐浓度的增加，3个种源的麻栎叶片叶绿素a、叶绿素b、净光合速率（P_n）均呈下降趋势，其中叶绿素a在山东种源中降幅最大，下降了21.5%～36.1%，四川种源降幅最小，在3.5%～19.8%之间.所有种源对照组的P_n均成“单峰”曲线，未出现“午休”现象；高盐浓度处理下则有明显的午休现象，经通径分析，P_n主要受饱和水汽压差和叶温的影响，气孔导度、胞间CO₂浓度和光强是次要因子.不同种源对照处理的麻栎叶片光合特征受原种源地环境因子的影响较大.麻栎的耐盐胁迫能力大小为：四川万源种源>安徽滁州种源>山东费县种源.

Photosynthetic characters of Quercus acutissima from different provenances under effects of salt stress

The photosynthetic characteristics of Quercus acutissima from Feixian, Chuzhou and Wanyuan provenances were investigated under NaCl stress at 5 concentrations. For the three provenances, their leaf chlorophyll a (Chl a) and chlorophyll b (Chl b) contents and net photosynthetic rate (Pn) decreased with increasing salt stress, among which, the maximal decrement of Chl a content was 215%〖KG-*2〗-〖KG-*7〗361% for Feixian provenance, and 35%〖KG-*2〗-〖KG-*7〗198% for Wanyuan provenance. The diurnal variation of Pn in control groups had a single peak, and no midday photosynthetic depression was observed. Under high salt stress, all the provenances presented midday photosynthetic depression. Path analysis indicated that the major factors affecting Pn were vapor pressure deficit (VPD) and leaf temperature (Tl), while the minor factors were stomatal conductance (Gs), intercellular CO2 concentration (Ci), and photosynthetically active radiation (PARi). In the control groups, the photosynthetic characteristics mainly depended on the climate factors of provenance location. Based on the variations of leaf chlorophyll contents and Pn among the provenances under different salt stress, Wanyuan provenance had the highest salt tolerance, followed by Chuzhou provenance, and Feixian provenance.