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首页> 外文学位 >Hydraulic and canopy conductances in hybrid poplar clones.
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Hydraulic and canopy conductances in hybrid poplar clones.

机译：杨树杂种无性系的水力和冠层电导。

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摘要

Hydraulic and stomatal resistances were related to growth and water use in hybrid poplar clones. Poplar trees are valuable for wind protection if they can grow under moisture limitation by maintaining their ability to take up moisture while effectively controlling water loss. Hydraulic resistance is therefore as important as the resistance provided by the stomata. Canopy conductance increased rapidly in the early mornings and then decreased throughout the day, implying a limitation on water supply to the leaves. However, since leaf water potential remained constant (isohydric) for most of the day, stomatal conductance did not control sap flow in the stem, except by regulating the leaf water potential. This meant that the tree's hydraulic resistance, which controlled leaf water supply and leaf water potential was important for combined drought tolerance and growth. Diurnal decrease in root water potential and an increase in hydraulic resistance were inferred from sap velocity patterns. However, irrigation resulted in decreased hydraulic resistance over several weeks in drought-stressed trees, which was attributable to biotic factors. These results implied that leaf water potential and control of root hydraulic resistance were important factors in drought tolerance of poplars. Leaf water potential was less negative in Northwest poplar, which performed better in a dry year than Walker poplar, suffered less shoot dieback and had more sapwood. This suggested that Walker poplar was more likely to sustain xylem cavitation in terminal shoots and in the stem. The clonal differences implied that clone-by-site interactions should be expected, with Walker poplar performing better on wet sites and Northwest poplar performing better on dry sites.
机译：水力和气孔阻力与杂交杨树无性系的生长和耗水量有关。杨树如果能够在保持水分吸收能力并有效控制水分流失的情况下在水分受限的情况下生长，则对于防风很有用。因此，水力阻力与气孔提供的阻力一样重要。冠层电导率在清晨迅速增加，然后全天下降，这意味着对叶片供水的限制。但是，由于叶片水势在一天的大部分时间内保持恒定（等渗），因此气孔传导率无法控制茎中的汁液流动，除非通过调节叶片水势。这意味着控制树木叶片供水和叶片水势的树木的水力阻力对于综合的干旱耐受性和生长至关重要。从树液速度模式推断出根水势的日减少和水力阻力的增加。但是，灌溉导致干旱胁迫的树木在数周内的水力阻力降低，这归因于生物因素。这些结果表明，叶水势和根系水力阻力的控制是杨树抗旱性的重要因素。西北杨树的叶片水势负值较小，在干旱的一年中其表现优于沃克杨树，梢枯死少，边材多。这表明Walker杨树更有可能在末梢和茎中维持木质部空化。克隆差异暗示应该进行逐位克隆的相互作用，其中沃克杨树在湿地上表现更好，西北杨树在干燥地上表现更好。

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  • 作者

    Kort, John.;

  • 作者单位

    University of Toronto (Canada).;

  • 授予单位 University of Toronto (Canada).;
  • 学科 Agriculture Forestry and Wildlife.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 森林生物学;
  • 关键词

  • 入库时间 2022-08-17 11:42:31

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