应用IMAGING-PAM荧光仪测定了离体脱水胁迫不同时期梭梭和胡杨的叶绿素荧光动力学参数。结果表明:离体胁迫初期(3 h) Fv /Fm、qP和ETR轻微降低,但胡杨的降低幅度比梭梭大;而此时qN 却明显增加,胡杨的增加幅度远大于梭梭。随着离体时间的延长(6、12 h) ,胡杨的Fv /Fm、qP和ETR 明显降低,梭梭的降低幅度仍相对较小;而此时qN 呈降低趋势,梭梭低于对照水平,而胡杨仍旧高于对照。这也说明遭遇不同程度胁迫时,梭梭和胡杨启动了不同的过剩光能防御机制。

Euonymus evergreen hybrid(1#, 2#, 3#) and their parents (Euonymus japonicus‘Zhuzi’, E. kiautschovicus) were studied to test whether their cold resistance were stronger than their parents in the winter. The result showed The semi-lethal temperatures (LT50) were assessed separately by electrolyte leakage, the result showed that the LT50 of 1#, 2#, 3#, E. japonicus‘Zhuzi’ and E. kiautschovicus were 36℃, 32.1℃, -28.5℃, -26.9℃, and -28℃ respectively. The activities of superoxide dismutase (SOD), peroxidase (POD) in 3# were higher than that of the others, but there was no significant difference among the other varieties. The contents of proline in leaves of E. japonicus‘Zhuzi’ were higher than that of Euonymus evergreen hybrids and E. kiautschovicus. The present study indicates that the hybrid evergreen euonymus and their parents had different mechanisms of cold-resistance.

目的 冬季低温是决定高山林线树种能否生存的重要生态因素。休眠前后树木体内碳水化合物的变化能够反映出其安全越冬的策略。但目前高山林线树种休眠前后体内碳水化合物的变化及机理尚不清楚。为了探讨林线树种越冬期间的生存策略， 方法 本文以祁连山林线青海云杉为对象，研究了不同海拔（2 900、3 000、3 100、3 200、3 300 m）成年树枝、叶休眠前后非结构性碳水化合物含量变化，包括可溶性糖（葡萄糖和果糖）、淀粉以及糖/淀粉比值的变化。 结果 表明：（1）休眠前青海云杉当年及1年生叶在高海拔处NSC含量高于中、低海拔处NSC含量，而在枝条中高、中、低海拔间没有显著差异。（2）休眠后叶中NSC含量最高值在中海拔3 100 m处，显著高于高海拔；不同组织中NSC含量高于休眠前，叶片中尤为明显。（3）与休眠前相比，休眠后可溶性糖及淀粉含量增加，淀粉含量增加幅度显著，引起可溶性糖/淀粉比值降低。 结论 青海云杉休眠前贮存足够的碳水化合物保证越冬期间的细胞渗透调节及能量代谢，并且休眠后气温升高时叶片和枝条的NSC能够得到迅速补充，为新枝条萌发提供充足的碳源，反映了青海云杉在越冬期间的生存策略。