Abstract Knowledge about heat acclimation in perennial plants is limited. Our hypotheses were (i) that high temperature during budswell before budbreak elicits acclimation in grapevines that is mediated by greater water transport capacity, and (ii) that water deficit modulates acclimation to high temperature. We compared field grown Malbec grapevines heated before budbreak during 3 or 15 days with untreated controls. We also combined these thermal regimes with two water regimes, well-watered and water deficit. The heat treatment was applied to vines enclosed in individual chambers. Under well-watered conditions, 3 days of heating during budswell were enough to increase number and diameter of primary xylem vessels in the emerging shoots, leaf stomatal density, transpiration, CO2 assimilation, shoot hydraulic conductance, specific shoot hydraulic conductivity, rates of shoot growth, leaf and lateral shoot appearance. Water deficit, while influencing xylem architecture, before budbreak did not alter the temperature effects on the water transport capacity. In vines with water deficit before budbreak, shoot hydraulic conductance was correlated with primary vessel number and total area of vessels, while in well-watered vines, with vessel size and total area of vessels. Irrigation practices need to manage this tradeoff between adaptation to elevated temperature and increased risk of hydraulic failure in plants with more and larger xylem vessels.

中文翻译：

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葡萄萌芽期的高温增加了地上部水分输送能力

摘要 关于多年生植物热驯化的知识是有限的。我们的假设是 (i) 萌芽前萌芽期间的高温引起葡萄藤的适应，这是由更大的水分输送能力介导的，以及 (ii) 水分亏缺调节对高温的适应。我们将在 3 或 15 天内在萌芽前加热的田间种植马尔贝克葡萄藤与未处理的对照进行了比较。我们还将这些热状况与两种水状况相结合，充足浇水和缺水。热处理应用于封闭在单独室中的葡萄藤。在充分浇水的条件下，萌芽期加热 3 天足以增加新芽中初级木质部血管的数量和直径、叶片气孔密度、蒸腾作用、CO2 同化、芽水导、比枝条导水率、枝条生长速率、叶和侧枝外观。水分亏缺虽然影响木质部结构，但在萌芽前并未改变温度对水分输送能力的影响。在萌芽前缺水的葡萄藤中，枝条水力传导度与主血管数量和血管总面积相关，而在水分充足的葡萄藤中，则与血管大小和血管总面积相关。灌溉实践需要在适应高温和具有更多和更大木质部容器的植物中增加水力故障风险之间进行权衡。在萌芽前缺水的葡萄藤中，枝条水力传导度与主血管数量和血管总面积相关，而在水分充足的葡萄藤中，则与血管大小和血管总面积相关。灌溉实践需要在适应高温和具有更多和更大木质部容器的植物中增加水力故障风险之间进行权衡。在萌芽前缺水的葡萄藤中，枝条水力传导度与主血管数量和血管总面积相关，而在水分充足的葡萄藤中，则与血管大小和血管总面积相关。灌溉实践需要在适应高温和具有更多和更大木质部容器的植物中增加水力故障风险之间进行权衡。