Daily and seasonal changes of water potential in cereals

Abstract

The paper reports measurements of the water relations of a barley crop (cv. Proctor) and a winter wheat crop (cv. Maris Huntsman), grown on the same site at Sutton Bonington. Throughout the two growing seasons, days were chosen when hourly measurements could be made of leaf water potential, by means of a pressure chamber, and of stomatal resistance, by means of a diffusion porometer. Environmental factors, e.g. radiation, temperature, humidity, were recorded concurrently. Relationships between leaf water potential, stomatal resistance and environmental factors are explored and compared for the two cereals. In particular, as frequent measurements were made over two months, the influence of leaf age on responses to environmental factors can be examined. On selected days with bright sunshine and dry soil the response of both cereals to water stress is analysed with particular reference to the control of evaporation by stomatal closure