Comparing canola and wheat seedling use of different sources of phosphorus

Abstract

A glasshouse study, using soil collected from two sites, was undertaken to compare how 30‐day‐old seedlings of canola (Brassica napus) and wheat (Triticum aestivum) utilized phosphorus (P) from freshly‐applied (current) triple superphosphate (TSP), and TSP and rock phosphate [North Carolina and Queensland (Duchess) apatites] (RP) applied in field experiments 11 years previously (previous P). The P was applied to the soil surface and incorporated into the top 10 cm of soil with a rotary hoe. After application of the current P in the field, samples of the <2‐mm fraction of the top 10 cm of soil were collected for the glasshouse study. Both canola and wheat produced poor yields without P but responded strongly to applied P. Regardless of the source of P (current and previous TSP, previous RP), canola required less P than wheat to produce the same percentage of the maximum yield of dried tops. For each amount of applied P, the concentration of P in dried tops was from about 30 to 120% higher for canola than wheat, indicating that canola roots were better able than wheat roots at accessing P from the soil, regardless of the source of P.

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