THE RELATIONSHIP BETWEEN PEACH TREE TRANSPIRATION AND EFFECTIVE CANOPY COVER

A short-term experiment was conducted at Tatura, Australia to determine the effects of reducing effective canopy cover (ECC) on transpiration (T) of an isolated well-watered field grown peach tree.
ECC was progressively reduced by de-branching over a 14-day period.
T was estimated from 15-minute measures of sap velocity at sixteen positions in the trunk sapwood.
Reference crop evapotranspiration (ET_o) was determined from meteorological data collected in a nearby automatic weather station.
Peach basal crop coefficient (K_cb) was calculated as the ratio of T to ET_o. ECC was estimated prior to each de-branching event using a combination of digital photographs of the tree taken from the direction of the sun and the fraction of PAR intercepted on the soil surface within the area of shade cast by the tree.
Over a 4-day period prior to de-branching, T and ET_o averaged 40 L d^-1 and 4.7 mm d^-1, respectively, and ECC was 5.8 m². Both T and K_cb declined with reduction in ECC. Leaf conductance and ET_o remained relatively constant for most of the experiment.
There was a strong positive linear relationship between K_cb and ECC (K_cb = 1.4 x ECC). These results suggest that T in an orchard may be estimated from a simple measure of the shaded ground area and ET_o. Implications for irrigation management are discussed.

IV International Symposium on Irrigation of Horticultural Crops

I. Goodwin, D.M. Whitfield, D.J. Connor

basal crop coefficient, sap flow, reference crop evapotranspiration, leaf conductance, PAR interception

https://doi.org/10.17660/ActaHortic.2004.664.34