2018 Volume 87 Issue 4 Pages 291-297
“Setokirara”, a wheat cultivar for bread making, tends to have a low grain protein content in spite of its high yield. In this study, we examined the effect of applying nitrogen fertilizer after anthesis on the grain protein content and the nitrogen accumulation in plant organs. The nitrogen fertilizer was applied by two methods: spreading soil surface with ammonium sulfate and foliar spraying with urea in solution. Furthermore the foliar spraying was performed by three methods: (1)spraying the full amount at anthesis, (2) spraying half the amount at anthesis and the other half one week after anthesis and (3) spraying the full amount at one week after anthesis. The grain yield was not increased by any method of nitrogen topdressing. The grain protein content was increased by all methods of topdressing, but there were no differences between ammonium sulfate and urea, or with the time of applying urea. Nitrogen from foliar spraying of urea was temporarily accumulated in vegetative organs, leaf + chaff + culm, and then translocated to grains. Nitrogen from ammonium sulfate applied to the soil surface was also accumulated in vegetative organs in one season, but was accumulated directly in grain not through vegetative organs in another season. Both nitrogen content and SPAD value of leaves were increased by nitrogen topdressing, but dry matter weight was not increased. Nitrogen application increased chlorophyll accumulation in leaves, but surplus chlorophyll did not appear to increase dry matter production.
