Effects of waterlogging on soil aeration and on root and shoot growth and yield of winter oats (Avena sativa L.)

Summary Winter oats were grown outdoors in lysimeters containing monoliths of a sandy loam soil. The soil was either freely-drained throughout the experiment or waterlogged to the soil surface from mid-January until mid-April. After the start of waterlogging the oxygen flux density decreased most rapidly nearer the soil surface and in the upper 50 cm declined to zero. At 80 cm depth the oxygen flux density at the end of the waterlogging still had not diminished to zero. While the soil was waterlogged root growth was negligible in the 20–50 cm zone of the soil profile, whereas below that depth root growth continued, reaching 95 cm by the end of the treatment. During the latter part of the waterlogging period root growth resumed in the upper 10 cm, and in the upper 2.5 cm was greater than in the freelydrained treatment.At the end of the waterlogging period, the total root length and shoot dry weights were 77 and 60% of those in the freely-drained treatment, tillering was restricted and leaf area index diminished. However, by anthesis, root length and shoot weights of the plants that had been waterlogged were only 10 and 12% less respectively than for the freely-drained plants. At harvest, total dry matter and grain yields were only 9% less, the latter largely through fewer grains per panicle.