气候与深层土壤双重干旱胁迫对苹果树水分传输的影响

树木体内水分高效、安全地传输是保障林地生产力和可持续性的关键。在全球苹果种植面积最大的黄土高原地区，果树正面临来自气候和深层土壤的双重干旱胁迫。然而，双重干旱胁迫对果树水分传输的影响尚不明确，严重制约对果树用水安全和苹果产业发展可持续性的认知。本研究以黄土塬区深层土壤干旱程度递增的苹果园为研究对象，通过降水再分配，建立双重干旱胁迫程度不同的试验处理，测定基于土壤-大气水势差的双重干旱胁迫强度、基于树干液流和枝条比导率的水分传输效率、基于枝条栓塞程度和栓塞脆弱性的水分传输安全性。构建干旱胁迫强度与水分传输效率和安全性的相关方程，明确双重干旱胁迫对二者的影响；进一步分析传输效率和安全性的关系，厘清果树为应对干旱而权衡水分传输效率和安全性的过程，并通过各处理枝条形态结构差异探明调节水分传输权衡的主控因子，揭示双重干旱对果树水分传输的影响机制，为黄土高原苹果产业健康、可持续的发展提供科学依据。

Efficient and safe water transfer in trees is the key to ensure forest productivity and sustainability. The Loess plateau is the world's largest apple planting area. In this region, apple trees are facing dual drought stress from climate and deep soil. However, the impact of dual drought stress on water transport in fruit trees is still unclear, which severely restricts the perception of water usage safety of fruit trees and the sustainable development of the apple industry. In this study, the apple orchards with increasing drought intensity in deep soil are selected. All the selected apple orchards are located on the flat tableland. Precipitation redistribution is conducted in each orchard to establish the experimental treatment with different degree of dual drought stress. Then, we investigate the dual drought stress intensity based on the difference of water potential between soil and atmosphere, the water transport efficiency based on sap flow and specific conductivity of branch, the water transport safety based on branch embolism degree and embolic vulnerability. Based on these measurements, the relationship between drought stress intensity and water transport efficiency and safety is constructed to clarify the influence of dual drought stress on them. The relationship between transport efficiency and transport safety is further analyzed to clarify the trade-off process between water transport efficiency and water transport safety in response to drought. The main controlling factors that regulate the water transport trade-off are explored through compare the differences in the morphology and structure of branches among treatments. The results of this study are projected to clarify the interaction between water transport and dual drought stress, and provide scientific basses for the healthy and sustainable development of the apple industry on the Loess Plateau.