Unraveling the effects of plant hydraulics on stomatal closure during water stress in walnut
Unraveling the effects of plant hydraulics on stomatal closure during water stress in walnut
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DOI：
10.1104/pp.010400
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发表时间：
2002-01-01
期刊：
影响因子：
7.4
通讯作者：
Améglio, T
中科院分区：
文献类型：
--
作者：
Cochard, H;Coll, L;Améglio, T
本研究的目的是确定相关的水力参数与气孔调节水分胁迫期间，并测试假设的气孔控制木质部栓塞核桃（核桃X黑）树。采用不同的方法改变植物蒸腾速率和气孔导度，研究了植物液流通道的水力特性。盆栽树木暴露于土壤水分耗竭，改变土壤水势（PSI（土壤）），土壤阻力（R-土壤），和根水力阻力（R-根）。土壤温度的变化，以改变R-根单独。在树干中产生栓塞以增加芽抗性（R-芽）。气孔关闭响应这些压力的影响，保持在-1.4 MPa以上的叶轴木质部（P-rachis）和叶水势（Psi（叶））在-1.6 MPa以上。E-plant和g（s）对P-rachis或Psi（leaf）的依赖性始终相同。这表明，气孔不响应PSI（土壤）R-根或R-芽本身的变化，而是他们对P-轴和/或PSI（叶）的影响。叶轴是最脆弱的器官，与阈值P-轴栓塞诱导-1.4 MPa。最小Psi（叶）值对应于叶膨压损失点。这表明气孔响应于由蒸腾速率和植物水力学决定的叶片水分状况，并且P轴可能是水分胁迫期间气孔关闭调节的生理参数，这将具有防止水分胁迫期间空化的广泛发展的效果。
The objectives of the study were to identify the relevant hydraulic parameters associated with stomatal regulation during water stress and to test the hypothesis of a stomatal control of xylem embolism in walnut (Juglans regia X nigra) trees. The hydraulic characteristics of the sap pathway were experimentally altered with different methods to alter plant transpiration (E-plant) and stomatal conductance (g(s)). Potted trees were exposed to a soil water depletion to alter soil water potential (Psi(soil)), soil resistance (R-soil), and root hydraulic resistances (R-root). Soil temperature was changed to alter R-root alone. Embolism was created in the trunk to increase shoot resistance (R-shoot). Stomata closed in response to these stresses with the effect of maintaining the water pressure in the leaf rachis Xylem (P-rachis) above - 1.4 MPa and the leaf water potential (Psi(leaf)) above - 1.6 MPa. The same dependence of E-plant and g(s) on P-rachis or Psi(leaf) was always observed. This suggested that stomata were not responding to changes in Psi(soil) R-root or R-shoot per se but rather to their impact on P-rachis and/or Psi(leaf). Leaf rachis was the most vulnerable organ, with a threshold P-rachis for embolism induction of - 1.4 MPa. The minimum Psi(leaf) values corresponded to leaf turgor loss point. This suggested that stomata are responding to leaf water status as determined by transpiration rate and plant hydraulics and that P-rachis might be the physiological parameter regulated by stomatal closure during water stress, which would have the effect of preventing extensive developments of cavitation during water stress.