Wheat genotypes differ in growth and phosphorus uptake when supplied with different sources and rates of phosphorus banded or mixed in soil in pots

Abstract

The growth response of wheat genotypes supplied with phosphorus fertiliser at different rates (banded or mixed throughout the soil) and sparingly soluble phosphorus sources (aluminium phosphate and iron phosphate) is not known. Eleven wheat genotypes and 1 rye genotype were tested at 3 rates of phosphorus fertiliser application (5, 10 and 20 mg P/kg soil) in a pot study. Another experiment compared 4 wheat genotypes at 2 rates of phosphorus application (deficient and sufficient) and 2 application methods (banding and mixing throughout the soil). The selected wheat genotypes were also used to investigate growth and root exudation response to iron phosphate and aluminium phosphate supply.

Banding of phosphorus fertiliser increased the uptake of phosphorus and wheat growth compared with mixing phosphorus throughout the soil. Wheat genotypes did not differ significantly in growth and phosphorus uptake at the low rate of application. With increasing rates of phosphorus supply, the 2 phosphorus-fertiliser-responsive wheat genotypes (Wawht 2074 and Aroona) had significantly increased phosphorus uptake and root and shoot weights. When supplied with aluminium phosphate and iron phosphate, the 2 phosphorus-fertiliser-responsive genotypes had larger roots and higher concentration of phosphorus in the shoots and roots, while the phosphorus utilisation-efficient wheat genotypes (Westonia and Gutha) had higher shoot weights than phosphorus fertiliser-responsive ones. All wheat genotypes produced quantitatively and qualitatively similar root exudates in the iron phosphate, aluminium phosphate and zero-phosphorus treatments. The aluminium phosphate treatment caused genotypes to increase root exudation of oxalic anions, uptake of phosphorus and growth, compared with the iron phosphate treatment. It was concluded that the choice of genotypes for achieving increased wheat growth would depend on the phosphorus source in soil and the rate of application of phosphorus fertiliser.