Institute of Forest Ecology, Slovak Academy of Sciences, Stúrova 2, 960 53 Zvolen, Slovakia.
Tree Physiol. 2010 Feb;30(2):205-13. doi: 10.1093/treephys/tpp116. Epub 2009 Dec 28.
Four-year-old seedlings of Picea abies [L.] Karst (Norway spruce) were grown in semi-controlled conditions with three watering regimes. The seedlings in the control group (c) were watered to prevent any dehydration effect. The two remaining groups were subjected to mild (ms) and severe water stress (ss), respectively. The following physiological variables were monitored until ss seedlings began to die: leaf water potential (psi(L)), stomatal conductance (g(s)), CO(2) exchange (P(N)), free proline content (Pro), total chlorophyll (a + b) concentration (Chl(t)) and the maximal photochemical efficiency of photosystem II (F(v)/F(m)). The results indicate that not all observed physiological parameters display the same degree of sensitivity to dehydration. After Day 12 of dehydration, psi(L) of ss seedlings was already significantly lower than that of the two other groups. On Day 26, significant differences in psi(L) were recorded among all treatments. Decreasing values of water potential were accompanied by early changes in P(N), g(s) and Pro. A significant decrease in Chl(t) and F(v)/F(m) were only observed during the more advanced stages of dehydration. These results demonstrate that the drought response of P. abies seedlings include a number of parallel physiological and biochemical changes in concert, enhancing the capability of plants to survive and grow during drought periods, but only to a point.
四年生挪威云杉（Picea abies [L.] Karst）幼苗在半控条件下用三种浇水制度进行生长。对照组（c）的幼苗浇水以防止任何脱水效应。其余两组分别受到轻度（ms）和重度水分胁迫（ss）的影响。在 ss 幼苗开始死亡之前，监测了以下生理变量：叶片水势（psi(L)）、气孔导度（g(s)）、CO(2)交换（P(N)）、游离脯氨酸含量（Pro）、总叶绿素（a + b）浓度（Chl(t)）和光系统 II 的最大光化学效率（F(v)/F(m)）。结果表明，并非所有观察到的生理参数对脱水的敏感性都相同。在脱水的第 12 天，ss 幼苗的 psi(L)已经明显低于其他两组。在第 26 天，所有处理之间记录到 psi(L)的显著差异。水势的降低伴随着 P(N)、g(s)和 Pro 的早期变化。仅在脱水的更后期阶段才观察到 Chl(t)和 F(v)/F(m)的显著下降。这些结果表明，挪威云杉幼苗的干旱响应包括一系列平行的生理和生化变化，增强了植物在干旱期间生存和生长的能力，但只是在一定程度上。
