Fotelli M N, Radoglou K M, Constantinidou H I
Forest Research Institute, National Agricultural Research Foundation (NAGREF), Vassilika, 57006 Thessaloniki, Greece.
Tree Physiol. 2000 Oct;20(16):1065-75. doi: 10.1093/treephys/20.16.1065.
Effects of water stress on phenology, growth, stomatal activity and water status were assessed from April to November 1996 in 2-year-old seedlings of Quercus frainetto Ten. (Quercus conferta Kit.), Quercus pubescens Willd., Quercus macrolepis Kotschy (Quercus aegilops auct.) and Quercus ilex L. growing in containers in northern Greece. All four species developed more than 50% of their total leaf area before the beginning of June--an adaptation to arid climates. Well-irrigated plants tended to develop greater individual leaf area, number of leaves per plant, total plant leaf area, height and root:shoot ratios than water-stressed plants, but the difference between treatments was not significant for any parameter in any species. Quercus macrolepis appeared to be the most drought-tolerant of the four species. It maintained the highest number of leaves of the smallest size and increased the proportion of fine roots during drought. In all species, drought caused significant decreases in stomatal conductance and predawn and midday water potentials from mid-July until the end of August, when the lowest soil water content and highest mean daily air temperatures and midday leaf temperatures occurred; however, the responses were species-specific. Among the four species, Quercus macrolepis sustained the highest stomatal conductance despite very low water potentials, thus overcoming drought by means of desiccation tolerance. Quercus ilex decreased stomatal conductance even before severe water stress occurred, thereby avoiding desication during drought. Quercus pubescens had the highest water potential despite a high stomatal conductance, indicating that its leaf water status was independent of stomatal activity. Quercus frainetto was the least drought-resistant of the four species. During drought it developed very low water potentials despite markedly reduced stomatal aperture.
1996年4月至11月，对生长在希腊北部容器中的2年生弗氏栎（Quercus frainetto Ten.，即Quercus conferta Kit.）、柔毛栎（Quercus pubescens Willd.）、大鳞栎（Quercus macrolepis Kotschy，即Quercus aegilops auct.）和冬青栎（Quercus ilex L.）幼苗，评估了水分胁迫对物候、生长、气孔活动和水分状况的影响。所有这四个物种在6月初之前就长出了超过其总叶面积50%的叶子，这是对干旱气候的一种适应。与水分胁迫的植株相比，充分灌溉的植株往往具有更大的单叶面积、单株叶片数量、植株总叶面积、高度以及根冠比，但对于任何一个物种的任何参数而言，处理之间的差异均不显著。大鳞栎似乎是这四个物种中最耐旱的。在干旱期间，它保持了数量最多但叶片最小的叶子，并增加了细根的比例。在所有物种中，从7月中旬到8月底，干旱导致气孔导度以及黎明前和中午水势显著下降，此时土壤含水量最低，平均每日气温和中午叶片温度最高；然而，这些反应具有物种特异性。在这四个物种中，尽管水势很低，但大鳞栎仍保持了最高的气孔导度，从而通过耐干燥性克服干旱。冬青栎甚至在严重水分胁迫发生之前就降低了气孔导度，从而在干旱期间避免脱水。柔毛栎尽管气孔导度很高，但水势最高，这表明其叶片水分状况与气孔活动无关。弗氏栎是这四个物种中最不耐旱的。在干旱期间，尽管气孔孔径明显减小，但它的水势却很低。
