The greater seedling high-light tolerance of Quercus robur over Fagus sylvatica is linked to a greater physiological plasticity
The greater seedling high-light tolerance of Quercus robur over Fagus sylvatica is linked to a greater physiological plasticity
复制标题
DOI：
10.1007/s00468-002-0184-4
复制
发表时间：
2002-08
期刊：
影响因子：
--
通讯作者：
F. Valladares;J. Chico;I. Aranda;L. Balaguer;P. Dizengremel;E. Manrique;E. Dreyer
中科院分区：
文献类型：
--
作者：
F. Valladares;J. Chico;I. Aranda;L. Balaguer;P. Dizengremel;E. Manrique;E. Dreyer
在法国南希的一个森林苗圃中生长了2年后，在夏季研究了栎树和山毛榉幼苗对4种不同的光环境(全光、50%、40%和15%日照)和快速增加的光照的反应。在大多数变量上，这两个物种之间存在显著差异。山毛榉对形态变量(根冠比、叶大小、叶重比)的表型可塑性高于橡树，而对解剖变量(气孔密度、表皮厚度、栅栏组织交换表面积)和生理变量(最大光合速率、气孔导度、Rubisco活性)的表型可塑性则相反。黎明前，除15%日照外，栎树的光化学效率(Fv/Fm)均高于山毛榉；100%日照下，山毛榉的Fv/Fm显著低于其他光环境，但栎树的Fv/Fm不显著。两个树种的最大光合作用速率(Amax)都随着光能利用率的增加而增加，但橡树的最大光合作用速率始终高于山毛榉。在全光照条件下，栎木表现出比山毛榉更高的Rubisco活性。遮荫苗木移栽到露地后，Fv/Fm下降，山毛榉的下降幅度大于栎树。被转移的栎树而不是山毛榉逐渐恢复到对照的Fv/Fm值。在强光下观察到的山毛榉幼苗叶绿素含量的降低和非光化学猝灭的增加不足以避免光抑制。结果表明，对强光的更大耐受性与增强的生理可塑性(与光合作用有关的变量)有关，而遮荫耐受性取决于采光变量(树冠形态和叶绿素含量)的可塑性增强。
The responses ofQuercus robur(oak) andFagus sylvatica(beech) seedlings to four different light environments (full, 50%, 40% and 15% sunlight) and to a rapid increase in irradiance were explored during the summer, after 2 years of growth in a forest nursery at Nancy (France). Significant differences between the two species were found for most variables. Phenotypic plasticity for morphological variables (root-shoot ratio, leaf size, leaf weight ratio) was higher in beech than in oak, while the reverse was true for anatomical (stomatal density, epidermis thickness, exchange surface area of the palisade parenchyma) and physiological (maximum photosynthetic rate, stomatal conductance, Rubisco activity) variables. Predawn photochemical efficiency (Fv/Fm) was higher in oak than in beech in all light environments except in 15% sunlight.Fv/Fmwas significantly lower in 100% sunlight than in the other light environments in beech but not in oak. Maximum photosynthetic rates (Amax) increased with increasing light availability in the two species but they were always higher in oak than in beech. Oak exhibited higher Rubisco activity than beech in full sunlight. The transfer of shade-adapted seedlings to the open caused a decrease ofFv/Fm, which was larger for beech than for oak. Transferred oak but not beech plants recovered gradually to the controlFv/Fmvalues. The decreased chlorophyll content and the increased non-photochemical quenching observed in high-light beech seedlings were not enough to avoid photoinhibition. The results suggest that a greater tolerance of strong irradiance is linked to an enhanced physiological plasticity (variables related to photosynthesis), while shade tolerance relies on an enhanced plasticity in light-harvesting variables (crown morphology and chlorophyll content).