Estimation of Diurnal Changes in Potato Leaf Water Potential Under Irrigated Conditions

in Journal of the American Society for Horticultural Science
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  • 1 Department of Plant, Soil and Entomological Sciences, University of Idaho, Aberdeen, ID 83210

Abstract

Regression models of potato (Solanum tuberosum L. cv. Russet Burbank) leaf water potential (ψleaf) were developed for irrigated conditions using concurrent measurements of total solar irradiance (Rs), air vapor pressure deficit (VPD), air temperature (Ta) and windspeed. Estimates of potential evaporation (Ep) also were related to ψleaf. The data were collected over a 3-year period from two locations in southern Idaho. Of the variables tested, Rs had the highest simple correlation with ψleaf (r = 0.93), although a slightly higher correlation was obtained for log-transformed values of VPD (1n VPD). Potato ψleaf was best described by the equation ψleaf = -0.3672 - 0.1959 In VPD – 0.0005 Rs, where ψleaf, VPD, and Rs are expressed in units of MPa, kPa and W·m–2, respectively. The model accounted for 95% of the variation in ψleaf for well-watered ‘Russet Burbank’ potatoes. When the model was tested on an independent data set, it estimated diurnal changes in ψleaf for several different cultivars to within ±0.1 MPa of the measured values. The relationship between ψleaf and Ep was nonlinear and was described by an exponential function. Estimates for the Ep model were nearly identical to those for the VPD Rs model when ψleaf values were below -0.3 MPa.

Contributor Notes

Associate Professor.

Assistant Professor, Dept. of Plant, Soil and Entomological Sciences, Univ. of Idaho, Univ. Place, P.O. Box 460, Idaho Falls, ID 83401.

Assistant Professor, Dept. of Agricultural Engineering, Univ. of Idaho Res. and Ext. Ctr., Aberdeen, ID 83210.

Received for publication 7 July 1986. Univ. of Idaho Agricultural Experiment Station Research Paper no. 86722. We express appreciation to J.L. Wright, ARS/USDA, for his assistance in the collection of data from the Snake River Conservation Research Center, Kimberly, Idaho. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.