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采取盆栽、人工控水的方式,研究并比较了美国本土海滨桤木(Alnus maritima)和薄叶桤木(A.incana)的气孔导度(Gs)、叶片水势(ψleaf)以及渗透调节能力对土壤水分条件的响应,以探讨引起两种桤木生态分布差异巨大的生理生态原因。结果表明:1)正常水分条件下,海滨桤木的Gs低于薄叶桤木,其与大气温度、相对湿度和水蒸气亏缺等气象因子的相关性低于薄叶桤木;干旱胁迫下,海滨桤木的Gs对其自身ψleaf下降信号的敏感度低于薄叶桤木;复水后,其Gs恢复更为缓慢。2)正常水分条件下,海滨桤木的ψleaf高于薄叶桤木,且引起气孔关闭的ψleaf临界值较高;干旱胁迫下,海滨桤木的ψleaf下降幅度高于薄叶桤木。3)正常水分条件下,海滨桤木和薄叶桤木的渗透调节能力无显著差异;干旱胁迫下,尽管两种桤木均表现出饱和状态渗透势(ψssat)下降、膨压与水势关系的最大变化率降低、初始失膨点渗透势(ψstlp)增加、细胞渗透调节能力范围(ψssat–ψstlp,Dψs减小的趋势,但与薄叶桤木相比,海滨桤木的ψstlp较高,Dψs较小。从以上生理生态指标可以看出,较高的叶片水势、较低的气孔调节能力、干旱下较低的渗透调节能力是造成海滨桤木分布范围狭小的重要原因。
Potted and artificial water control methods were used to study and compare the stomatal conductance (Gs), leaf water potential (ψleaf) and osmotic adjustment ability of Alnus maritima and A.incana in the United States. Soil moisture conditions in order to explore the ecological differences caused by two kinds of aloe huge ecological and physiological reasons. The results showed as follows: 1) Under normal water conditions, the Gs of Alnus cremastogyne was lower than that of Alnus cremastogyne, and its correlation with meteorological factors such as atmospheric temperature, relative humidity and water vapor deficit was lower than that of Alnus cremastogyne. Under drought stress The sensitivity of the Gs to the ψleaf descent signal was lower than that of the thin-walled Alnus cremastogyne. After rehydration, the Gs recovered more slowly. 2) Under normal water conditions, the ψleaf of Alnus cremastogyne was higher than that of Alnus cremastogyne, and the ψleaf critical value that caused the stomatal closure was higher. Under α stress, the ψleaf of Alnus cremastogyne decreased more than that of Alnus cremastogyne. Under normal water conditions, the osmotic adjustment ability of Alnus cremastogyne and Alnus cremastogyne without significant difference; under drought stress, although both alnus showed saturated osmotic potential (ψssat) decreased, turgor pressure and water potential (Ψsat-ψstlp, Dψs) decreased, but the maximum ψstlp was higher, and the average value of Dψs The results showed that higher leaf water potential, lower stomatal regulation, and lower osmotic adjustment ability under drought were the main reasons for the narrow distribution of Alnus cremastogyne.