中文摘要：

以黑龙江地区优势杨树的3个无性系‘A5’（Populus pseudo—simonii×P．nigra）×（P．simonii×P.nigra）、‘J7’（P．deltoidis×P．catyana CL．‘J7’）和‘1344’（P．deltoides×P．cathayana CL．‘1344’）当年生幼苗为实验材料，进行NaCl胁迫实验，各处理NaCl质量／干土质量分别为0％，0．3％、0．5％、0．7％，测定杨树幼苗的生长和光合生理特征参数的变化。结果表明：NaCl胁迫下无性系‘1344’各处理盐害症状出现的时间最早，受害程度最大，其次为‘J7’。随着处理时间增加，株高基径差异性逐渐加大，分别比对照下降10％～35％。叶绿素a含量随NaCl浓度增加而下降，‘J7’叶绿素a含量随NaCl浓度增加而下降的趋势大于‘A5’和‘1344’。类胡萝卜素含量‘A5’表现为随NaCl浓度增加而上升，而‘J7’和‘1344’表现为随NaCl浓度增加而下降；0．3％NaCl胁迫下叶绿素b含量‘A5’和‘1344’高于对照，‘A5’在0．5％和0．7％NaCl胁迫下叶绿素b含量与对照差异不显著，‘1344’在0．3％与0．5％NaCl胁迫下显著高于对照和0．7％NaCl胁迫；‘J7’在0．3％NaCl胁迫下与对照差异不显著，高于0．5％与0．7％。光合速率随NaCl浓度增加而下降，‘1344’幼苗的最大光合速率（Pmax）下降速率最快，‘A5’的Pmax受NaCl胁迫影响最小。气孔导度（Gs）和胞间CO2浓度（Ci）随NaCl浓度增加而下降，气孔限制值（Ls）呈降低趋势，表明影响杨树幼苗的光合作用是气孔限制和非气孔限制的共同作用的结果。水分利用效率（WUE）在3种杨树幼苗中的各NaCl浓度下均维持较高水平，NaCl浓度为0．7％时‘A5’幼苗的WUE仍保持很高的水平。综上分析，3个杨树无性系中‘A5’幼苗耐盐能力最强。

英文摘要：

We studied the response of photosynthetic physiological characteristics of three poplar clone seedlings to NaCl stress with three kinds of poplar（Populus L. ） clones of poplar（Populus L. ） clone seedlings including ＇ A5＇ （ Populus pseudo-simonii ×P. nigra） × （ P. simonii × P. nigra ）, ＇ J7＇ （ P. deltoidis × P. catyana CL. ＇J7＇） and ＇1344＇ （P. deltoids × P. cathayana CL. ＇1344＇） in Heilongjiang Province. Three NaCl stress treatments were established at the contents of 0.3%, 0.5% and 0.7% （ percentage of NaCl in total dry soil mass）. The salt injury symptoms first appeared in ＇ 1344＇ under NaCl stress, followed by ＇J7 ＇ and ＇ A5 ＇ Furthermore, under the same NaCl content, the maximum damage due to NaCI stress also occurred first in ＇1344＇ , followed by ＇J7＇ and ＇A5＇. The mean tree diameter at breast height and total tree height differed signi？ cantly under three NaCl stress treatments. Moreover, the difference between three NaCl stress treatments gradually become bigger, which was 10% -35% lower than the control treatment during the late period of this experiment. With the increase of NaCl, the chlorophyll content decreased, with the decrease in ＇J7＇ being much more obvious than in ＇ A5＇ and ＇ 1344＇ With the increase of NaCl, the content of carotenoid in ＇ A5＇ increased, and ＇J7＇ and ＇1344＇ decreased. Chlorophyll b content under 0.3% NaCl stress in ＇A5＇ and ＇1344＇ was higher than that in the control, while the ＇A5＇ chlorophyll b content under the 0.5% and 0.7% NaCl stress levels were in contrast not significantly different, but ＇ 1344＇ under 0.3% and 0.5% NaCl stress levels was significantly higher than that in the control and the 0.7% NaCl stress level. ＇ J7 ＇ showed no significant difference when compared with the 0.3% NaCl stress, hut was higher than the 0.5% and 0.7% levels. The photosynthesis of the clone see decreased with the increase of the salt, dlings reduced due to the NaCl stress.