MECHANISMS OF DROUGHT AVOIDANCE IN KIWIFRUIT VINES

Ecophysiological parameters were evaluated in well-watered and water stressed kiwifruit (Actinidia deliciosa var. deliciosa) vines grown either in containers or in the field to evaluate mechanisms of resistance to water stress.
Stomatal conductance rapidly decreased as pre-dawn leaf water potential (_w) was reduced below a threshold value of -0.3 MPa.
Stomatal closure determined a marked decrease in leaf transpiration and a significant increase in leaf temperature.
Both leaf _w and relative water content (RWC) remained high even at extreme water deficits which caused leaves to lose turgor and reorient away from direct sunlight.
There was no evidence of osmotic adjustment due to active accumulation of solutes in the leaf.
These changes indicate that kiwifruit behaves as a typical drought-avoiding species with a limited potential to withstand drought.
As soil moisture is depleted kiwifruit responds in a conservative way by closing stomata and reducing transpiration, which further limits water uptake by establishing a low gradient in _w between the canopy and the root.
The practical implications for irrigation management are discussed.

III International Symposium on Kiwifruit

R. Gucci, R. Massai, C. Xiloyannis

https://doi.org/10.17660/ActaHortic.1997.444.48