Leaf structure and patterns of photoinhibition in two neotropical palms in clearings and forest understory during the dry season
Leaf structure and patterns of photoinhibition in two neotropical palms in clearings and forest understory during the dry season
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DOI：
10.1002/j.1537-2197.1994.tb15507.x
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发表时间：
1994-06
影响因子：
3
通讯作者：
J. Araus;K. Hogan
中科院分区：
文献类型：
--
作者：
J. Araus;K. Hogan
我们在巴拿马巴罗科罗拉多岛的空地（高光 [HL] 棕榈）和森林林下（低光 [LL] 棕榈）的自然旱季条件下研究了两种棕榈（Socratea exorriza 和 Scheelea zonensis）的叶子结构、水分状况和快速荧光响应。与 HL-Scheelea 相比，HL-Socratea 叶片更耐荫、更少旱生，且受干旱影响更强烈。两个物种的 HL 叶中的 Fv/Fm（可变叶绿素荧光与最大叶绿素荧光的比率）和 t（Fm 的半上升时间）较低，表明存在光抑制。在 HL-Scheelea 中，光诱导的 Fv/Fm 降低远小于 HL-Socratea，并且 Fv/Fm 一夜之间完全恢复。相对含水量、特定叶片干重、稳定碳同位素组成和叶片电导的模式表明，Scheelea 抗旱性的增强降低了对光抑制的敏感性。 F0 的增加表明 HL-Socratea 中 PSII 反应中心失活。 HLSocratea 中极低的叶绿素 a/b 比率和叶绿体超微结构的改变与光抑制一致。在 LL 下，该物种在叶绿素荧光方面没有表现出明显的种间差异。过量的光照导致 HL 植物相对于 LL 植物在两个叶表面（尤其是下表面）的 Fv/Fm 值较低，这是由于两个表面的 Fm 降低而下表面的 F0 增加。对于这两个物种，HL 植物下表面的 Fo 较高，而 t 明显低于上表面，这对于遮荫叶子来说是典型的。旱形叶结构可以降低旱季对光抑制的敏感性。干旱增强的光抑制可能会限制某些物种利用树木倒塌间隙的能力。
We studied the leaf structural, water status, and fast fluorescence responses of two palms, Socratea exorrhiza and Scheelea zonensis, under natural dry season conditions in a clearing (high light [HL] palms) and the forest understory (low light [LL] palms) on Barro Colorado Island, Panama. HL-Socratea leaves were more shade-adapted, less xeromorphic, and more strongly affected by drought than HL-Scheelea. Fv/Fm (the ratio of variable to maximum chlorophyll fluorescence) and t, (the half-rise time of Fm) was lower in HL-leaves of both species, indicating photoinhibition. In HL-Scheelea, the lightinduced reduction of Fv/Fm was much less than in HL-Socratea, and Fv/Fm recovered completely overnight. Patterns of relative water content, specific leaf dry weight, stable carbon isotope composition, and leaf conductance suggest that increased drought resistance in Scheelea reduces susceptibility to photoinhibition. An increase in F0 indicated the inactivation of PSII reaction centers in HL-Socratea. The very low chlorophyll a/b ratio and alterations in chloroplast ultrastructure in HLSocratea are consistent with photoinhibition. Under LL, the species showed no appreciable interspecific differences in chlorophyll fluorescence. Excess light leads to low values of Fv/Fm in HL-plants relative to LL-plants on both leaf surfaces, particularly on the lower surface, due to a decrease of Fm in both surfaces and an increase in F0 of lower surface. For both species, Fo for the lower surfaces of HL-plants was higher and t, was markedly lower than for the upper surface, as is typical for shade-adapted leaves. Xeromorphic leaf structure may reduce susceptibility to photoinhibition during the dry season. Drought-enhanced photoinhibition could limit the ability of some species to exploit treefall gaps.