COMPARATIVE PHOSPHORUS REQUIREMENT OF 4 LUPIN SPECIES

The yield response of yellow lupin (Lupinus luteus), sand plain lupin (L. cosentinii), narrow-leafed lupin (L. angustifolius), and white lup in (L. albus) to applications of phosphorus (P), as single superphosph ate (0 to 80 kg P ha(-1)), was measured in the year of application in a field experiment on a sandy soil. Comparative P requirement was dete rmined from yields when no P was applied, the amount of P required to produce the same percentage of the maximum (relative) yield, such as 9 0% of the maximum yield, and the P content measured in dried tops. For all these criteria, P requirement generally increased in the order L. cosentinii < L. albus < L. angustifolius < L. luteus. Proteoid roots, found only on L. cosentinii and L. albus plants, were probably respon sible for these species using indigenous soil P and applied fertilizer P more effectively than L. luteus and L. angustifolius.