Variation in seedling growth of 11 perennial legumes in response to phosphorus supply

Abstract

Phosphorus (P) deficiency is a major problem for Australian agriculture. Development of new perennial pasture legumes that acquire or use P more efficiently than the current major perennial pasture legume, lucerne (Medicago sativa L.), is urgent. A glasshouse experiment compared the response of ten perennial herbaceous legume species to a series of P supplies ranging from 0 to 384 µg g⁻¹ soil, with lucerne as the control. Under low-P conditions, several legumes produced more biomass than lucerne. Four species (Lotononis bainesii Baker, Kennedia prorepens F.Muell, K. prostrata R.Br, Bituminaria bituminosa (L.) C.H.Stirt) achieved maximum growth at 12 µg P g⁻¹ soil, while other species required 24 µg P g⁻¹. In most tested legumes, biomass production was reduced when P supply was ≥192 µg g⁻¹, due to P toxicity, while L. bainesii and K. prorepens showed reduced biomass when P was ≥24 µg g⁻¹ and K. prostrata at ≥48 µg P g⁻¹ soil. B. bituminosa and Glycine canescens F.J.Herm required less soil P to achieve 0.5 g dry mass than the other species did. Lucerne performed poorly with low P supply and our results suggest that some novel perennial legumes may perform better on low-P soils.