A comparison of the responses of two cultivars of late-autumn-sown wheat to applied nitrogen

Abstract

SUMMARYAt four pairs of sites in the UK, two cultivars of wheat, bred either for autumn (cv. Mercia) or for spring (cv. Tonic) sowing were sown in November 1988 and 1989 and their yield response to springapplied fertilizer N assessed over the range 0–320 kg/ha N. Grain samples were taken at harvest and analysed for those qualities regarded as indicators of suitability for milling. In five experiments, the grain yield of Mercia was up to 1 t/ha greater than that of Tonic, but overall there was no consistent difference between the two cultivars in the optimum economic yield (Yopt)or in the amount of fertilizer N needed to produce it (Nopt). Both cultivars produced c. 17·5 kg of grain per kg of fertilizer N applied up to Nopl. In the five experiments in which Tonic yielded less, it produced grain of greater N concentration than Mercia when given the same amount of fertilizer N. Differences in grain N concentration, while small (< 0·3%), were significant when analysed across sites. In six experiments both cultivars produced grain of 11 % protein at Nopt. There were no consistent or worthwhile increases in specific weight, Hagberg falling number (HFN) or response to the sodium dodecyl sulphate (SDS) sedimentation test of either cultivar from applying more fertilizer N than Nopl. The average specific weight of Mercia grain was 2·5 kg/hi greater than that of Tonic, while Tonic gave larger SDS values of c. 8. There was little difference in HFN. It was concluded that the yield requirement for fertilizer N was similar for these two cultivars of wheat when sown in late autumn, and there was no need to apply differential fertilizer N applications to the cultivars to produce grain of the quality needed for breadmaking. In four experiments the application of plant growth regulator (PGR) increased the yields of both cultivars by c. 0·5 t/ha.