Effect of phosphorus on the growth and mineral composition of four tropical forage legumes

Abstract

The effect of phosphorus on the growth and mineral composition of four tropical pasture legumes-Centrosema pubescens, Centrosema plumeris, Puereria phaseoloides and Stylosanthes gracilis-was investigated in the greenhouse. All the species except P. phaseoloides responded to phosphorus application. C. pubescens required more phosphorus for optimum growth than C. plumeris and S. gracilis which required about the same amount,In the species, the potassium, sodium and calcium concentrations in plants given phosphorus seemed higher than that of the control except in S. gracilis where the potassium, and in Cplumeris where the calcium, concentration appeared to be lowered by phosphorus. The concentration of magnesium of C. plumeris seemed to be increased but unaffected in other species by phosphorus addition. Phosphorus tended to depress plant sulphur but it had no effect on percent nitrogen.The percentages of phosphorus, in the species for maximum growth at 65 days from sowing were: C. pubescens, 0.293 ; P. phaseoloides, 0.228 ; C. plumeris, 0.280; and S. gracilis, 0.270.