Effects of urea alone or with fungicide on the yield and breadmaking quality of wheat when sprayed at flag leaf and ear emergence

Urea (supplying 15 kg N/ha) applied to winter wheat (Triticum aestivum) at flag leaf emergence and again at ear emergence improved grain yield in only two, but increased grain nitrogen (N) in four out of five experiments. The size of the improvements in yield and nitrogen content differed over varying sites and seasons but were not affected by cultivar or propiconazole (250 g a.i./ha) plus tridemorph (500 g a.i./ha) fungicide applied with the urea. Breadmaking quality was assessed on grain from one site in 1985 and in 1986. The beneficial effects on loaf quality of urea and fungicide applied separately were reduced when they were applied as a mixture. In 1986 this negative interaction was associated with effects on sodium dodecyl sulphate (SDS) sedimentation volume, flour sulphur content (S), N/S ratio and dough resistance. The effect of urea also interacted with cultivar on SDS sedimentation volume in 1985 and dough resistance in 1986.