2020 Volume 89 Issue 4 Pages 307-316
We examined the relationships between nitrogen topdressing at flowering and grain ash content in the wheat variety “Yukichikara” for bread in a sand dune and upland field converted from paddy field of Niigata prefecture. In the sand dune, the grain ash content and phosphorus concentration were increased by nitrogen topdressing at flowering. In the upland field converted from paddy field, nitrogen topdressing at flowering did not affect grain ash content. This difference in these fields depended on the relationship between increment of grain phosphorus content per unit area and grain yield. The phosphorus uptake during the ripening period was increased by nitrogen topdressing at flowering, and the increment was greater in the sand dune than in the upland field converted from paddy field. Available phosphoric acid concentration (Truog P) was greater in the sand dune than in the upland field converted from paddy field, and a possible effect of the available phosphoric acid concentration on phosphorus uptake during ripening period was implied. These results suggest that the relationship between nitrogen topdressing at flowering and grain phosphorous concentration depends on the balance between increment of grain phosphorus content per unit area and that of grain yield. Additionally, it was implied that grain phosphorus concentration and grain ash content were increased by nitrogen topdressing at flowering in soil with high available phosphoric acid concentration.
