Articles
ESTIMATION OF CONTAINERIZED SINGLE-STEM AND SPLIT-ROOTED, NON-FRUITING APPLE TREE WATER USE USING MINIATURIZED HEAT PULSE PROBES
Article number
846_32
Pages
285 – 292
Language
English
Abstract
During the early summer of 2003, one-year-old Gala apple trees on M7 rootstock were potted into 30 L containers and maintained as either single-stem trees or approach grafted (dual-stem trees). Following callusing of approach grafts, one of the tops was selected for removal.
Experiments commenced in the spring of 2004. Actual crop evapo-transpiration (ETc) for single-stem trees was determined from gravimetric measurements, and compared to estimations of water use by heat pulse using the T-max method.
Throughout a three-week experimental period a good relationship existed between gravimetric and heat pulse measurements, however the T-max method consistently over-estimated daily water use of fully-irrigated, single-stem trees.
The relationship did however improve over time, likely the result of the rapid growth rate of young tissue.
For dual-stem trees, daily irrigation supplied a predetermined percentage of ETc (>100 or 50%) to individual trees and was either withheld from one root compartment or divided evenly between both root compartments.
For dual-stem trees, contribution to the total sap flow from a given root compartment showed a strong relationship to its trunk cross-sectional area.
Heat pulse and TDR gave similar estimations of water use for all treatments.
A combination of declining soil moisture, physiological and biochemical factors exerted control over sap flow.
Experiments commenced in the spring of 2004. Actual crop evapo-transpiration (ETc) for single-stem trees was determined from gravimetric measurements, and compared to estimations of water use by heat pulse using the T-max method.
Throughout a three-week experimental period a good relationship existed between gravimetric and heat pulse measurements, however the T-max method consistently over-estimated daily water use of fully-irrigated, single-stem trees.
The relationship did however improve over time, likely the result of the rapid growth rate of young tissue.
For dual-stem trees, daily irrigation supplied a predetermined percentage of ETc (>100 or 50%) to individual trees and was either withheld from one root compartment or divided evenly between both root compartments.
For dual-stem trees, contribution to the total sap flow from a given root compartment showed a strong relationship to its trunk cross-sectional area.
Heat pulse and TDR gave similar estimations of water use for all treatments.
A combination of declining soil moisture, physiological and biochemical factors exerted control over sap flow.
Publication
Authors
T. Einhorn, H.W. Caspari, S. Green
Keywords
Malus × domestica Borkh., partial rootzone drying, deficit irrigation, chemical signaling, T-max
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