Exploring hydraulic redistribution for water management in gardens

The understanding of water use by mixed stands, where trees and herbaceous share the same area, as in landscaping, requires at least the combined consideration of the role of water and radiation, as limiting factors for plant development and survival.
Hydraulic redistribution (HR), a mechanism of transport of water between different root zones via roots, is of high interest in this context.
Several studies in last decades, using bidirectional sap flow sensors in roots, and other tools, unlighted the role of this survival mechanism in potentially critical hydro-climatic conditions, i.e., when plants are subjected to severe water stress.
Woody plants can act as water transporters from underground deep layers to shallow soil layers, via their deep roots, as a result of water potential gradients.
Results from literature suggest that in doing so (HR) deep rooted plants not only ensure conditions for their own survival but also that, at certain stages, they increase the survival chances for other plants installed in nearby shallow layers.
Our hypothesis is that synergies between species exploring water from different soil layers can be identified in a simple experiment, the results being of potential interest for garden planning.
We show preliminary results obtained with olive trees in Mediterranean climatic conditions, and associated herbaceous plants, in a kind of split-root experiment.
Water status of herbaceous plants in three different conditions was evaluated from data on leaf water potential and stomatal conductance.
The results confirm our hypothesis in that herbaceous plants were significantly affected by water applied to part of the tree root system, even if not receiving irrigation directly.
This mechanism should be taken into account when creating sustainable urban gardens, in respect to water management.

XXX International Horticultural Congress IHC2018: VII Conference on Landscape and Urban Horticulture, IV Conference on Turfgrass Management and Science for Sports Fields and II Symposium on Mechanization, Precision Horticulture, and Robotics

S.V. Lourenço, M.I. Ferreira

water stress, irrigation, mixed stands, Mediterranean, landscaping

https://doi.org/10.17660/ActaHortic.2020.1279.14