Irrigated spring wheat and timing and amount of nitrogen fertilizer. II. Physiology of grain yield response

In order to understand the mechanism by which the timing and amount of N fertilizer affect grain yield of wheat, a large experiment comprising 32 N treatments (from nil to 320 kg N ha−1, applications from seeding to booting) was conducted using a high-yielding semidwarf spring cultivar grown under low natural fertility at Griffith, New South Wales (34°S). The weather was close to normal and supplemental spring irrigations eliminated the...