Responses of grain yield, biomass and harvest index and their rates of genetic progress to nitrogen availability in ten winter wheat varieties

Abstract

(0.34%/year; R 2 = 0.001), increased as year increased. Genetic gain in yield was smaller without fertiliser N (0.021 t ha −1 y −1 ; R 2 = 0.21) and at 40 kg ha N (0.025 t ha −1 y −1 ; R 2 = 0.25) than at 215–250 kg/ha N (0.065 t ha −1 y −1 ; R 2 = 0.39). Theoretically, if the maximum biomass (18.60 t/ha for Rialto), could have been combined with the maximum harvest index (55.3%) in Riband, yield would potentially have been increased by 2.5 t/ha compared with yields for either variety.