Sulphur nutrition: An important factor for the quality of wheat and rapeseed

The incidence of sulphur (S) deficiency has increased in many crops in the U.K. and other European countries in the last 10 years. Apart from the effects on yield, the S nutrition of a crop often has a strong influence on the quality of the produce. We have shown that S fertilisation significantly improved breadmaking quality of field-grown wheat (Triticum aestivum L.) in the U.K. with the loaf volumes of the same variety grown at different sites correlating better with the concentrations of grain S than grain N. Sulphur also increased gel protein content of flour, but decreased its elastic strength. In contrast, application of S fertilisers to oilseed rape (Brassica napus L.) can lead to increased glucosinolate concentrations in the seed which exceed the limit for the meal to be used in animal feeds. Results from 29 field experiments showed that the glucosinolate concentration of rapeseed was usually higher when grown at the S-sufficient than the S-deficient sites. However, the addition of S fertiliser increased the glucosinolate concentration much more under S-deficient than under S-sufficient conditions. Furthermore, there was a strong interaction between N and S on seed glucosinolates. Increasing N decreased the glucosinolate concentration when S was deficient, but increased the glucosinolate concentration when S was applied. The need to maintain a balanced N and S supply for both yield and quality is stressed.