THE DEVELOPMENT OF WATERLOGGING DAMAGE IN YOUNG BARLEY PLANTS IN RELATION TO PLANT NUTRIENT STATUS AND CHANGES IN SOIL PROPERTIES

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Abstract
Summary: When the soil in which 13‐day‐old barley plants were growing was flooded, the concentration of dissolved oxygen in the waterlogged soil declined to < 2 % (in the equilibrium gaseous phase) within 48 h. Within the same time there was injury to seminal roots and a reduction in the rate of leaf extension. The net rates of uptake of nitrogen, phosphate and potassium in shoots were reduced shortly after the onset of waterlogging, and because dry matter accumulation by shoots was initially little affected, the average concentration of these nutrients showed a marked decline after 48 h compared with aerated controls. The concentration of nitrate in shoots was particularly sensitive to waterlogging and after 48 h was about one third of that in controls. Analysis of individual leaves and tillers showed that with waterlogging, nitrogen was accumulated by the younger tissues at the expense of the older leaves. This trend, which was not observed with plants in aerobic soil, preceded the premature breakdown of chlorophyll in the older leaves.With prolonged anaerobiosis, there were increases in the concentration of potentially inhibitory soil products (ethylene, organic acids, manganese) and a decline in nitrate in the soil solution, but these changes, which mostly occurred after the onset of the characteristic symptoms of waterlogging damage were relatively small and unlikely to have led to injury to shoots. The possible relations between the low concentration of oxygen around roots, the inhibition of ion uptake, the redistribution of nutrients within the shoot, and the premature senescence of leaves are discussed.