Flooding tolerance of some Western Australian pasture legumes

Abstract

The effect of flooding on several varieties of clover was studied in three separate experiments. In experiment 1 ten cultivars of subterranean clover (Trifolium subterraneum), two of strawberry clover (T. fragiferum), two of white clover (T. repens) and Serradella (Ornithopus sativa) were subjected to two flooding treatments 77 days after planting. With the water table at ground level, herbage yields were not significantly less than those of unflooded plants in Yarloop, N2254, Yabba North, Wenijup, Palestine, and Salina and New Zealand white clovers, hut there were significant decreases in yield in N2167, N2168, Clare, Geraldton, Mt. Barker, Morocco, Ladino, and Serradella. When the water table was raised to three inches above ground level, all the cultivars had significantly lower herbage and root yields than the control plants. Overall, Yarloop appeared to be the most productive under both of the flooding treatments. In experiment 2 Yarloop and Geraldton clovers were flooded at three different stages of growth (one third eleven days after planting, one third sixty days after planting, and one third 86 days after planting). Flooding lasted 21 days then half of each group was harvested and the other half allowed to grow for a further 14 days under free drainage before harvesting. Both Geraldton and Yarloop were affected most by flooding sixty days after planting. Nodulation was delayed in the plants that were flooded eleven days after planting, but commenced once the soil was allowed to drain freely. In experiment 3, eight Yarloop crosses were flooded three inches above ground level for 21 days, 80 days after planting. The crosses were subdivided on seed colour. Flooding reduced yield in all crosses except Yarloop x Yabba Noah brown seed and Yarloop x Mt. Barker brown seed. The data suggest that breeding for greater tolerance to flooding may be practicable.