Increasing phosphorus concentration in lupin seed increases grain yield on phosphorus deficient soil

Abstract

In a field experiment on a phosphorus (P) deficient soil in south-western Australia, lupin seed (Lupinus angustifolius cv. Danja) of the same size (157 mg/seed) but with 2 different phosphorus (P) concentrations in the seed (2.0 and 2.8 g P/kg) was sown with 4 levels of superphosphate (5, 20, 40 and 60 kg P/ha) drilled with the seed in May 1988 to examine the effect of seed P concentration on subsequent dry matter (DM) and grain yields. Increasing the amount of superphosphate applied from 5 to 60 kg P/ha almost doubled yields. In addition, lupins grown from seed containing the higher P concentration produced larger yields of dried whole tops in early August (69-day-old) for all levels of superphosphate drilled with the seed, the difference decreasing from about 45 to 10% as the level of superphosphate increased from 5 to 60 kg P/ha. By maturity (mid- November), however, plants grown from seed containing the higher P concentration in seed produced higher DM yields of tops and grain only when 5 and 20 kg P/ha superphosphate was drilled with the seed, the differences being about 40 and 20%, respectively.