A model describing soil-plant-water relations for potatoes

Abstract

A simple steady state model is derived which describes the diurnal water potential fluctuations in leaves and tubers of potatoes. The magnitude of these fluctuations is shown to depend on transpiration rate, hydraulic properties of the soil, rooting depth and density, resistance to flow of water within the plant, and the leaf water potential at which stomatal closure occurs. Model predictions agree quite well with measurements made in the field and in the growth chamber. The model is used to predict the lower limit of readily available moisture for potatoes and shows the important environmental and plant factors.

Resumen

Se ha derivado un modelo simple de equilibrio dinámico para describir las fluctuaciones diurnas del potencial de agua en hojas y tubérculos de papa.

La magnitud de estas fluctuaciones muestra dependencia en la tasa de transpiración, propiedades hidráulicas del suelo, profundidad y densidad de enraizamiento, resistencia al flujo del agua dentro de la planta, y el potencial de agua de la hoja al cual ocurre el cierre de los estomas. Las predicciones del modelo concuerdan bastante bien con medidas hechas en el campo y en las cámaras de crecimiento. El modelo se usa para predecir el límite más bajo de humedad facilmente disponible para papa y muestra la importancia de los factores ambientales y de la mísma planta. The relationship between soil water potential and plant transpiration rate and growth is subject to considerable influence by soil, plant, and atmospheric factors. With most irrigation systems, it is desirable to maintain the soil water potential sufficiently high to maximize growth. Much research has been conducted to determine the lower limit of available water to plants and the relative availability of water at various soil water potentials. These determinations are often confounded by the influences of transpiration, leaf osmotic potential, root density and distribution, and hydraulic conductivity of the soil. The purpose of this paper is to describe a soil-plant-water flow model which takes these factors into account and apply it to determine the optimum soil water potential for maximizing potato growth.