期刊
PLANT AND SOIL
卷 425, 期 1-2, 页码 21-41出版社
SPRINGER
DOI: 10.1007/s11104-018-3585-x
关键词
Reverse flow; Survival strategies; Sap flow; Water uptake; Water stress
资金
- Fundacao para a Ciencia e Tecnologia (FCT, Portugal) [PTDC/AAC-AMB/100635/2008, SFRH/BD/66967/2009]
- Fundação para a Ciência e a Tecnologia [PTDC/AAC-AMB/100635/2008, SFRH/BD/66967/2009] Funding Source: FCT
Aims In this study on hydraulic redistribution (HR) in roots, we aimed to use the calibrated average-gradient (CAG) heat-pulse method, the novelty being the use of a much narrower averaging window for the signal analysis, in order to achieve a more linear calibration curve, allowing the HR quantification. Methods The study was conducted in 12 large roots of a rain-fed olive orchard, for 6 months without significant rain, when the predawn leaf water potential decreased to -2.4 MPa, and immediately following the first autumn rains. Results Detailed numerical modelling of the CAG method allowed verification of the response of the measurement system to a range of drivers, improving the linear range of the calibration response function, which has remained stable over the observations period. On average, reverse flow was observed during 30% of the summer nights and, in a conservative estimate, it increased to about 5% of total daily root flow before first autumn rain. Conclusions Reverse flow accounted on average for 2.6% of the total daily root flow, enabling upper roots to stay active during the very dry late-summer period. In qualitative terms, our results confirm the CAG method as a reliable tool to identify reverse flow and quantify HR when it occurs.
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