The effects of soil moisture stress on the growth of barley. II. Grain growth

Abstract

The influence of water stress on grain growth has been investigated under conditions of intermittent stress with pot-grown plants and under longer periods of stress with plants grown in lysimeters. Premature cessation of growth was induced by even a moderate water stress, but the rate of grain growth (in dry weight) in the early stages of development was reduced only by severe water stress. There was evidence for an actual loss of dry matter in the final stages of maturation where plants were subjected to severe water stress. Grain moisture content was relatively unaffected by water stress during the major period of grain development, although grain water content dropped with increasing water stress during ripening. Spikelet chlorophyll content was also reduced by water stress, particularly in the later stages of grain development. Indirect evidence indicated that translocation of assimilate from the leaves to the ear was reduced by a moderate water stress. Tne significance of these findings in elucidating the mechanism of action of water stress on grain growth is discussed.