|Author: ||H.J. Schenk|
|Keywords: ||plant hydraulics, xylem vulnerability, drought stress, plant-based measures, irrigation scheduling|
Plant-based measures of water stress are increasingly used in horticulture for irrigation scheduling.
A common outcome of water stress is the formation of air bubbles in the xylem, the hydraulic system of plants.
Most of the time, water in the xylem is under sub-atmospheric or negative pressure, which creates the possibility that air can be sucked into the conducting cells, forming xylem embolisms.
Embolisms can impede water transport in plants, in severe cases leading to death of roots, branches, or whole plants.
Formation of embolisms in some perennial crops has been characterized through so-called xylem vulnerability curves, which document the degree of xylem embolization as a function of xylem water potentials.
Grapevine varieties are among the most studied plants, but embolism formation has also been studied in varieties of asparagus, apple, peach, plum, walnut, olive, citrus, coffee, and other horticultural crops.
Many plant species, including some horticultural crops, have been found to have the ability to remove air bubbles from the xylem and refill the conducting cells with water even while the xylem is transporting water under negative pressure.
Most research on embolism repair has focused on bay laurel and grapevine.
Except for the species named, not much is known about the embolism repair capability in horticultural crops.
To date, measurements of embolism formation and repair have not been used for making irrigation decisions.
It is proposed that research into embolism formation and repair in horticultural plants will lead to a better understanding of their drought tolerance and will aid in water conservation by leading to better plant-based measures for irrigation scheduling.
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