The effect of nitrogen rate and timing on grain yield and grain protein of eight wheat varieties – Coonamble 2012

Abstract

Key findings • Only one variety, LongReach Impala[PBR], had a significant increase in grain yield as a result of the application of nitrogen (N) (only at 100 kg/ha N rate). Both EGA Gregory[PBR] and Caparoi[PBR] had significant reductions in grain yield as a result of the application of nitrogen. • Where no N was applied, the grain yield of EGA Gregory[PBR], Sunguard[PBR] and Suntop[PBR] were similar; however Sunguard[PBR] and Suntop[PBR] were able to maintain grain yield with increased N application. • Yield of most varieties was maximised at grain protein concentrations less than 10%, which goes against the 11% protein ‘rule of thumb’. • LongReach Spitfire[PBR] had a higher grain protein concentration than all other varieties and also maintained good grain size at increased N rates. • Increasing the rate of N at sowing increased pre-anthesis dry matter production which left less water available for grain fill post-anthesis.