The objective of this work is to test the strength of relationships between maximum trunk daily shrinkage (MDS), soil matric potential (SMP) for various soil depths, and some weather variables in grown plum trees and medium-textured soils under continental-temperate climate conditions. The obtained relationships might be used in identification of water stress for irrigation scheduling. The study was carried out in a 7–9-year-old plum tree orchard plot with the ‘Stanley’ cultivar grafted on Saint Julien A semi-dwarf rootstock. Micrometric trunk diameter fluctuations of three trees were automatically measured by phytomonitors, and SMP was monitored continuously with resistance blocks installed in three profiles at four depths: 0.2, 0.4, 0.6 and 0.8 m during many wetting-drying cycles during two growing seasons. Strong and highly significant regression equations were obtained between MDS and air temperature (T) and daily vapor pressure deficit (VPD) for three growing seasons of observations. There were also weaker but significant relationships between MDS and SMP for all the four depths studied. Multiple linear regression equations between MDS, SMP for all the four depths, and either maximum T or VPD generally improved R² from the simple regression equations obtained with each of the same variables. The MDS threshold of 0.08–0.12 mm approximately corresponds to a SMP range of about −60 to −40 kPa; however, due to the high MDS variability in time and the weight of the weather variables in the relationships between MDS, SMP and weather variables like T or VPD, the usefulness of these relationships is limited.

中文翻译：

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中质地土壤和温带气候下树干最大日收缩量，土壤基质势与天气变量的相关性

这项工作的目的是测试大陆温带气候下不同土壤深度的最大树干日收缩率（MDS），土壤基质势（SMP）以及生长的李子树和中等质地土壤中的一些天气变量之间的关系的强度。条件。所获得的关系可以用于识别灌溉计划中的水分胁迫。该研究是在一个7–9岁的李子果园地中进行的，其中将“ Stanley”品种嫁接在Saint Julien A半矮砧木上。通过植物监测器自动测量三棵树的树干直径的细微波动，并在两个生长季节的多个干湿循环中，通过安装在三个剖面中的阻力块在四个深度（0.2、0.4、0.6和0.8 m）连续监测SMP。在三个生长季节的观测中，在MDS与气温（T）和日蒸气压亏缺（VPD）之间获得了强大而高度显着的回归方程。在所有研究的四个深度中，MDS和SMP之间也存在较弱但重要的关系。对于所有四个深度，MDS，SMP之间的多个线性回归方程以及最大T或VPD通常都会改善R从使用每个相同变量获得的简单回归方程式中得出²。MDS阈值0.08-0.12 mm大约对应于SMP范围约-60至-40 kPa；但是，由于MDS在时间上的高度可变性以及MDS，SMP与天气变量（如T或VPD）之间关系中天气变量的权重，这些关系的实用性受到了限制。