The extensive grazing systems of northern Australia are dominated by C₄ grasses and are established in N- and P-responsive soils that receive minimal nutrient input. Under these conditions, tropical pasture legumes are expected to improve the quality of grazing forage and fix atmospheric N₂. However, legume persistence is relatively poor, which may be due to a presumed disparity in P requirements among tropical pasture species. This disparity suggests that P-efficient legumes may improve legume persistence, yet the P requirements of many tropical pasture legumes remain unquantified. Nine Desmanthus spp. genotypes were grown in pots to determine differences in shoot yield and root morphology in response to soil P supply (0–100 mg applied P kg^–1 soil; 5–63 mg Colwell P kg^–1 soil). The shoot yield of each genotype increased in response to increased P supply. When P supply was adequate for maximum plant growth, the shoot yield of the best genotype (3.5 g DM pot^–1; JCU 9) was 1.7-fold larger than that of the next most productive genotype. There were also substantial differences in the critical external P requirements of the genotypes (29.4–64.0 mg P kg^–1 soil), although these differences did not always reflect the efficiency of dry matter production per unit of applied P fertiliser. Differences in shoot yield and P acquisition were positively associated with differences in the development of root length. The results indicated that P-efficient genotypes of Desmanthus spp. can be identified for improved growth in the P-responsive pastures of northern Australia. These genotypes may compete more effectively with C₄ grasses and form resilient pasture swards as climate patterns change.

澳大利亚北部广泛的放牧系统以C ₄草为主，并在对氮和磷敏感的土壤中建立，这些土壤吸收的养分最少。在这种情况下，热带牧场豆科植物有望改善牧草的质量并固定大气中的N ₂。但是，豆科植物的持久性相对较差，这可能是由于热带牧草物种对磷的需求存在推测差异所致。这种差异表明，磷高效的豆科植物可能会改善豆类的持久性，但许多热带牧场豆类对磷的需求量仍未确定。九丹参属。基因型在盆中生长，以确定响应于土壤磷的供应（0–100 mg施用的P kg ^–1），枝条产量和根系形态的差异泥; 5–63 mg Colwell P kg ^–1土壤）。每种基因型的枝条产量都随着磷供应的增加而增加。当磷的供应足以最大程度地增加植物的生长时，最佳基因型（3.5 g DM盆^–1； JCU 9）的苗产量比第二高产基因型高1.7倍。基因型的关键外部磷需求量也有实质性差异（29.4–64.0 mg P kg ^–1土壤），尽管这些差异并不总是反映出每单位施用P肥料的干物质生产效率。枝条产量和磷素吸收的差异与根长发育的差异呈正相关。结果表明，木犀属植物的P型有效基因型spp。可以确定在澳大利亚北部的P响应型牧场中改善生长。这些基因型可能会与C ₄草竞争更有效，并随着气候模式的变化而形成有韧性的牧草。