NITRATE REDUCTASE-ACTIVITY AND PRODUCTIVITY OF GRAIN CROPS UNDER WATERLOGGED CONDITIONS

The effect of waterlogging on potential and actual nitrate reductase activity, the nitrate content of the soil, and the ultimate productivity of two grain crops that differ in their tolerance of oxygen deficiency (oats, which is tolerant, and wheat, which is not) is studied. Two weeks of waterlogging during the elongation stage caused a decline in the nitrate reductase activity of both crops and a drop in productivity. But the nitrate reductase activity of oats was higher than that of wheat, and the oats exhibited a correspondingly smaller decline in productivity. Waterlogging produced a nitrate buildup in the soil under wheat, but not that under oats; the buildup was greater when ammonia nitrogen fertilizer was applied than when nitrate nitrogen was applied.