Influence of sulfur on growth and nutrient composition of soft red winter wheat

Sulfur (S) deficiencies in soft red winter wheat (Triticum aestivum L.) result in reduced yields and inferior grain quality. Diagnosis of S deficiency has been unreliable since soil testing does not accurately measure available soil S, and tissue S concentration varies with plant age. In order to establish more reliable guidelines for determining S deficiency in winter wheat we used nutrient solution culture to provide uniform conditions for determining the effect of tissue S content on dry matter accumulation and nutrient uptake. The critical level of S for 90% of maximum growth in winter wheat seedlings (Feekes scale 1 with 5 leaves) was calculated at 1.4 g kg^‐1 using a modified Mitscherlich model. Root growth was less sensitive to low S levels than top growth which may reduce the effect of S deficiency in the field. Concentrations of N, Mg, Fe, and Cu in the plant tissue increased with increased S concentration. An N/S ratio of greater than 22 was associated with reduced growth. Our results suggest that if care is taken in standardizing the plant age when sampling early diagnosis of S deficiency could be based on total S analysis.