水分胁迫条件下4个杨树无性系气体交换特征比较

选用两个速生的（群众杨４４和欧美杨２５／８６）和两个慢生的杨树无纱水培苗木，在不同温度适应下进行水分梯度胁迫和解除胁迫处理，测定了不同叶室相对湿度条件下净光合速率（Ｐｎ）、气孔导率Ｃｓ及蒸腾强度（ＴＲ）等生理指标，试验结果表明，小叶杨和群众杨４４耐旱及恢复能力比两个欧美杨强。４个无性的Ｐｎ差异显著性受温度和相对湿度影响，产生无性系Ｐｎ差异的原因锖央气体扩散过程，也表现在非气体扩散过程（ＣＯ２固定的

GAS EXCHANGE CHARACTERISTICS OF FOUR POPLAR CLONES UNDER WATER STRESS

Plants of four poplar clones, Populus simonii (Clone A), P.euromericana 28/86(Clone B), P.popularis 44(Clone C), and P.euramericana 25/86(Clone D),were grown by water cultivated method, and then exposed to PEG (4000) solution with different osmotic potential and rewatering at different temperature regimes. Net photosynthesis rate (P n), stomatal conductance (Cs) and transpiration (TR) were measured at different relative humidity (RH%) in leaf chamber. Results showed that clone A and C were More drought tolerance than clone B and D. The difference in Pn among clones could be affected by temperature and air relative humidity. The reasons for the significant difference in Pn among clones were attributable to both gas diffusion between air and intercellular the physical process, and the biochemical process the fixation of CO2 underlying photosynthesis. Among majority of treatments were no significant differences in CS and TR among clones. It Could be inferred that the difference in P n among clones was mainly attributable to the biochemical process, and close relative to different genotypes.