【作者】 李秀媛；

【导师】 刘西平；

【作者基本信息】 西北农林科技大学 ， 植物学， 2010， 硕士

【摘要】 本文以美国本土海滨桤木和薄叶桤木为试验材料,采取盆栽、人工控水的方式研究并比较了海滨桤木(Alnus maritima)和薄叶桤木(A. incana ssp. tenuifolia)气孔导度(Gs)、叶片水势(ψleaf)、渗透调节能力以及光合性能对土壤水分条件的响应,以探讨引起两种桤木生态分布巨大差异的生理生态原因。结果表明:(1)正常水分条件下,海滨桤木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相关性低于薄叶桤木;干旱胁迫下,海滨桤木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恢复的更为缓慢。(2)正常水分条件下,海滨桤木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:(a)饱和状态渗透势(ψssat)下降,(b)膨压与水势关系的最大变化率降低,(c)初始失膨点渗透势(ψstlp)增加,(d)细胞渗透调节能力范围(ψssat-ψstlp)减小的趋势,但与薄叶桤木相比,海滨桤木ψstlp较高,ψssat-ψstlp较小。(4)海滨桤木最大净光合速率(Amax)、量子表观速率(AQY)、呼吸速率(Rd)、光补偿点(LCP)、光合速率(Pn)以及光下最大荧光(Fm’)、光合电子传递速率(ETR)和光化学淬灭系数(qP)均显著高于薄叶桤木,而光饱和点则低于薄叶桤木,表明海滨桤木对强光的适应性更低;干旱胁迫下两种桤木Pn和蒸腾速率(Tr)显著下降,水分利用率(WUE)上升,光系统Ⅱ(PSⅡ)的有效光化学量子产量(Fv’/Fm’)、ETR和非光化学系数(qN)显著下降,其中,海滨桤木变化幅度大于薄叶桤木。从以上结果可以看出,尽管在有效辐射范围内光合性能较强,但较低的气孔敏感性、较高的叶片水势、干旱下较低的渗透调节能力、较小的光合有效辐射范围以及对干旱较高的敏感性,是造成海滨桤木分布范围狭小的主要原因之一。更多还原

【Abstract】 This study compared stomatal conductance (Gs), leaf water potential (ψleaf), basic osmotic adjustment and photosynthetic responses of Alnus maritima and A. incana ssp. tenuifolia growing in America under artificial soil humidities, to explore physiological reasons of gigantic difference in ecological distribution of the both tree species. The results indicated that, (1) A. maritima kept a lower Gs and the correlation coefficients between A. maritima and meteorological factors ie. air temperature, vapor pressure deficit, relative humidity was lower than A. tenuifolia under well watered irrigation. During the dry-down period, A. maritima showed a weaker ability to keep stomatal open influenced by the decrease ofψleaf. In rewatered experiment, recovery speed of Gs of A. maritima was slower than that of A. tenuifolia.(2) Under well watered condition, A. maritima kept a higherψleaf and a higher threshold ofψleaf leading to stomata close compared to A. tenuifolia. Under drought stress, the decline inψleaf but was larger than A. tenuifolia.(3) There was no significant difference in the osmotic regulation of the two species. However, both species showed: (a) a decrease in solute potential at full turgor (ψssat) and, (b) a decline of maximum variation rate of turgor pressure against solute potential, (c) an increase in solute potential at turgor loss point(ψstlp), (d)ψssat-ψstlp dropped after surfing drought stressed. Noticeablyψstlp of A. maritima was higher, butψssat-ψstlp was lower than A. tenuifolia.(4) Light response curve of A. maritima showed a higher maximum net photosynthetic rate (Amax), apparent quantum yield (AQY), dark respiration rate (Rd) and light compensation point (LCP), but a lower light saturation point (LSP), compared with A. tenuifolia. Net photosynthetic rate (Pn), maximum fluorescence yield in light-adapted state (Fm’), non-cycle photosynthetic electron transport rate (ETR) and photochemical chlorophyll fluorescence quenching coefficient (qP) of A. maritima were higher than those of A. tenuifolia. Drought treatment led to a significant decrease in effective PS II quantum yield (Fv’/Fm’), in ETR and non-photochemical quenching coefficient (qN) in both species, particularly in A. maritima.These results indicated that the rarity and patchy distribution of A. maritima may partly attribute to (1) the lower sensitivity of leaf stomatal, (2) higher leaf water potential, (3) lower osmotic adjustment ability under drought stress, (4) higher sensitivity to drought stress and (5) smaller range of effective photosynthetic solar radiation.更多还原