M.A. GILBERT and K.A. SHAW
Queensland Department of Primary Industries P.O. Box 1054, Mareeba, Qld 4880, Australia
The effects of sulphur supply on growth and chemical composition of a range of Stylosanthes species were examined in glasshouse and field experiments. Species were S. humilis cv. Paterson, S. hamata cv. Verano, S. guianensis cvv. Endeavour, Graham, Schofield, and CPI 34906, S. scabra cv. Seca, and S. viscosa CPI 34904. Some legumes were not included in both experiments.
For each legume, sulphur application increased yield of shoots and roots in the glasshouse experiment. The external requirement for sulphur (i.e. the amount of applied sulphur required for 90% of maximum yield) was similar for all legumes, but CPI 34904 was slightly less sensitive to sulphur deficiency (i.e. yield of unfertilised Plants expressed as a percentage of maximum yield) compared to the others.
There were no differences in yield and sulphur concentration between legumes grown without added sulphur in either the glasshouse or field experiments., With increasing sulphur supply in the glasshouse, however, differences appeared between legumes in yield, sulphur concentration and uptake into shoots. Although the legumes had similar external requirements for sulphur, they had quite different critical sulphur concentrations, and these were inversely related to yield. We conclude that there is little difference in tolerance to sulphur deficiency between these legumes.