应用盆栽试验研究了不同盐(NaCl)胁迫下乌桕1年生幼苗光合特性与叶绿素指标的变化。结果表明：随着盐胁迫的加剧，GC2种源净光合作用速率（Pn）先上升后下降，其余种源Pn则随胁迫的加剧逐渐递减；在020 %（NaCl质量分数）盐胁迫下，与对照相比XN1与GC2两种源气孔导度（Gs）增大，其余种源Gs呈不同程度降低，按照降幅大小排序为：HS1、HZ2、GCH1、SC4。在质量分数为040 %与060 %的盐胁迫下，各种源Gs普遍低于对照；不同盐胁迫下各种源胞间CO2浓度（Ci）变化趋势不同；GC2、GCH1与HZ2种源叶绿素含量随盐胁迫的增加而下降，但XN1、SC4与HS1种源呈无规律变化。相关分析表明，Pn与Gs、Ci、Tr呈极显著正相关（p＜001），但与叶绿素指标的相关性不明显。依据幼苗光合速率降幅与叶绿素含量变化分析，在轻度盐胁迫下XN1与GC2具有较强的忍耐性，SC4与GCH1次之，而GC2种源在中度盐胁迫下仍能维持一定的光合作用，其耐盐能力最强。

Effects of salt stress on photosynthetic characteristics and chlorophyll content of Sapium sebiferum seedlings was studied. The results showed that the change of net photosynthetic rate (Pn) of Sapium sebiferum seedlings from various provenances was different. The Pn of GC2 provenance showed the tendency of increased first and then decreased. The change of the rest provenances was gradually descending with increasing of salt stress. Compared with control the stomatal conductance（Gs）of both XN1and GC2 provenances increased under 020 %NaCl stress, Gs of the rest provenances decreased. According to the change ranges, they were ordered as HS1>HZ2>GCH1>SC4. The Gs of whole provenances was lower than that of the control under 040 %,060 % NaCl stress. The intercellular CO2 concentration（Ci）of different provenances showed a distinct tendency. The chlorophyll content (Chl)of GC2,GCH1 and HZ2 provenances was gradually descending with increasing of salt stress, but provenances of XN1,SC4 and HS1 showed irregular changes. Correlation analysis showed that Pn was significantly positively correlated to Gs, Ci，Tr(p＜001),but correlation between Pn and Chl was not obvious. By combining the changing ranges of Pn and Chl, we drew a conclusion that both XN1 and GC2 provenance showed stronger tolerance under lower salt stress, SC4 and GCH1 took the second place, whereas GC2 provenances could keep certain photosynthesis under middle salt stress, and its tolerance to salt stress was the strongest.