Comparing the phosphorus requirements of wheat, lupin, and canola
2008
Bolland, M.D.A. | Brennan, R.F.
Spring wheat (Triticum aestivum L.), lupin (Lupinus angustifolius L.), and canola (Brassica napus L.) are the major crop species grown in rotation on the predominantly sandy soils of south-western Australia. Comparisons among the species for yield responses to applied phosphorus (P), effects of applied P on growth rates of shoots, P response efficiency for shoot and grain production, and the pattern for accumulation of P into shoots during growth and into grain at maturity are rare, or are not known, and were quantified in the glasshouse study reported here. Size and P content (P concentration multiplied by yield) of sown seed were in the order canola<wheat<lupin. Therefore, yield responses to applied P were first observed at ~10 days after sowing (DAS) for canola, ~17 DAS for wheat, and ~60 DAS for lupin. Lupin shoots showed no yield response to applied P at the first harvest at 51 DAS. Otherwise all species showed large yield, P concentration, and P content responses to applied P for all harvests at 51, 78, 87, 101, 121, and 172 DAS. To produce 90% of the maximum grain yield, the relevant data for cropping, lupin required ~67% less P than wheat, canola required ~40% less P than wheat, and canola required ~75% more P than lupin. Growth rates, and P response efficiency, were generally largest for canola, followed by wheat, then lupin. For shoots, P accumulation was in the order lupin>wheat>canola at 51 DAS, canola>wheat>lupin at 78 and 87 DAS, canola>wheat=lupin at 101 DAS, and all 3 species were about similar at 121 DAS. For accumulation of P into shoots plus grain at maturity (172 DAS) the order was canola>lupin>wheat, and for grain only was canola>wheat=lupin.
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