Influence of atmospheric and soil environmental parameters on the diurnal fluctuations of leaf water status of barley

Abstract

The effect of environmental parameters on the diurnal trend of leaf water status was determined on spring barley grown in soil near field capacity and near the permanent wilting point on a cool, mostly cloudy day and a warm, mostly clear day. Leaf relative water content and leaf water potential varied inversely to diurnal trends of air vapor pressure deficit, air temperature, soil surface temperature, wind velocity, pan evaporation, solar radiation, and net radiation. Leaf relative water content, leaf water potential and leaf temperatures were influenced by soil moisture content and day type. Vapor pressure deficit was negatively correlated with leaf relative water content. The correlation was −0.912 for pooled data with soil moisture near field capacity, and −0.943 for pooled data with soil moisture near the permanent wilting point. Highest correlation coefficients involving leaf water potential were obtained with soil surface temperature. The correlation was −0.862 with soil moisture near field capacity and −0.917 with soil moisture near the permanent wilting point. Leaf temperature and soil surface temperature were higher when soil moisture was near the permanent wilting point than when it was near field capacity. Leaf temperature appeared to be a sensitive indicator of plant water stress.