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首页> 外文期刊>Plant and Soil >Drought resistance of 2-year-old saplings of Mediterranean forest trees in the field: relations between water relations, hydraulics and productivity
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Drought resistance of 2-year-old saplings of Mediterranean forest trees in the field: relations between water relations, hydraulics and productivity

机译：地中海林木2岁树苗在田间的抗旱性：水关系，水力和生产力之间的关系

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Drought resistance was examined for 2-year-old saplings of Ceratonia siliqua L., Olea oleaster Hoffmgg. et Link., Quercus suber L. and Q. pubescens Willd. growing in the field in Sicily, with the aim of testing their possible use in the reforestation of degraded areas. To this purpose, leaf conductance to water vapour (g(L)), transpiration rate (E-L), relative water content (RWC) and water potential (Psi(L)) were measured between pre-dawn and sunset, monthly from May to November. Parallel measurements of loss of hydraulic conductance of twigs of the current year (PLC) were made together with an estimate of whole-plant hydraulic conductance (K-PLANT) on the basis of the ratio of maximum E-L to (Psi(PD) - Psi(MIN)), where Psi(PD) is pre-dawn Psi(L) and Psi(MIN) is the minimum diurnal Psi(L). C. siliqua saplings maintained high g(L) throughout the study period with high RWC (over 90%) and Psi(L). They grew rapidly and increased their foliage area (A(L)) by over 60% from May to winter rest. This was accompanied by low twig PLC ( about 20% in September) resulting in high K-PLANT all through the study period. In contrast, O. oleaster saplings underwent distinct dehydration in July, i.e. they showed stomatal closure due to a drop in RWC (to 75%) and Psi(L) (to the turgor-loss point). This was apparently due to twig cavitation, resulting in a strong decrease of K-PLANT. Plants, however, tolerated summer drought, and showed growth (A(L) increased by 15% from May to November). Saplings of Q. suber and Q. pubescens were much more vulnerable to twig cavitation ( PLC was 35-48% from June to November) than the other two species, and their average K-PLANT was lower. Saplings of Q. suber and Q. pubescens grew only during the wet spring period, and no new foliage was produced thereafter. Changes in twig hydraulic conductance played a dominant role in determining changes in K-PLANT in that the two variables were well correlated to each other (r = 0.68 for P = 0.001). We conclude that C. siliqua is an ideal candidate for reforestation of Sicilian degraded areas as is O. oleaster that, however, requires some additional water supply in the summer, at least during the early years after plantation. In wetter locations of Sicily, to an altitude between 0 and 500 m, Q. suber and Q. pubescens can be used for reforestation with expected higher competitiveness of the latter over the former species.
机译：检查了2岁的Ceratonia siliqua L.，Olea oleaster Hoffmgg的幼树的抗旱性。 et Link。，Quercus suber L. and Q. pubescens Willd。在西西里的田间种植，目的是测试它们在退化地区的重新造林中的可能用途。为此，从五月至五月的每月黎明至日落之间测量叶片对水蒸气的电导率（g（L）），蒸腾速率（EL），相对水含量（RWC）和水势（Psi（L））。十一月。根据最大EL与（Psi（PD）-Psi的比率）对当年树枝（PLC）的水力传导损失进行了并行测量，并估算了整个工厂的水力传导（K-PLANT）。 （MIN）），其中Psi（PD）是黎明前的Psi（L），而Psi（MIN）是最小的昼夜Psi（L）。在整个研究期间，长毛树苗保持较高的g（L），具有较高的RWC（超过90％）和Psi（L）。从五月到冬季休息，它们生长迅速，叶子面积（A（L））增加了60％以上。伴有低枝PLC（9月约为20％），导致整个研究期间的K-PLANT较高。相比之下，O。oleaster幼树在7月份经历了明显的脱水，即由于RWC（降至75％）和Psi（L）（达到了鼻gor消失点）而降低了气孔关闭。显然这是由于树枝气蚀，导致K-PLANT大大降低。然而，植物可以忍受夏季干旱，并表现出生长（从5月到11月，A（L）增加了15％）。比起其他两个物种，苏伯Q.suber和pubescens的幼树更容易受到树枝空化的影响（PLC从6月到11月为35-48％），它们的平均K-PLANT较低。 Suber和Q. pubescens的树苗仅在春季湿润时期生长，此后没有新的叶子生长。枝条水力传导率的变化在确定K-PLANT的变化中起主要作用，因为这两个变量之间具有很好的相关性（P = 0.001，r = 0.68）。我们得出的结论是，C。siliqua和S. oleaster一样是西西里退化地区重新造林的理想人选，然而，至少在种植后的最初几年，O。oleaster在夏天需要额外的水供应。在西西里岛较湿的地区，海拔在0至500 m之间，可以将Suber和pubescens进行重新造林，预计后者比前一个物种具有更高的竞争力。

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