Genotypic differences in wheat for uptake and utilisation of P from iron phosphate

Two glasshouse experiments were conducted to evaluate the genotypic variation amongst cereal genotypes in phosphorus uptake from relatively insoluble iron phosphate. Optimum rates of iron phosphate were established by growing 3 wheat and 1 triticale genotype on an infertile sand amended with iron phosphate. Shoot dry weight of all genotypes showed a classic Mitcherlich response with 95% maximum growth achieved with 174 mg P/kg soil. Two rates of FePO4 were selected representing a deficient and sufficient supply (26 and 339 mg P/kg soil, respectively).These rates were used to screen 99 wheat, 8 triticale, and 4 cereal rye genotypes for phosphorus-use efficiency. Phosphorus efficiency was rated by 4 criteria: shoot dry weight at deficient P supply, shoot weight at deficient supply relative to shoot weight at sufficient P supply, P uptake efficiency (amount of P taken up per unit of P supplied), and P utilisation efficiency (shoot weight per unit P in plant).No genotypes were rated as efficient under all 4 criteria. Only 2 genotypes were rated efficient (rye Bevy, rye PC00361) and one inefficient (Machete) under 3 criteria. Seven genotypes were rated as efficient on 2 indices (wheat Chinese 80-55, Westonia, and Wawht 2147; triticale Treat, AT48-94, and TX93-78-1; rye Bulgarian Pento), whereas 7 genotypes were rated as inefficient on 2 indices (Boricuta, Cadoux, Cunderdin, Insignia, Kalingri, Perenjori, and triticale Abacus). Significant genotypic variation was identified in cereals in the ability to take up and utilise P from poorly soluble Fe-P, although all genotypes were able to utilise this source of phosphorus to some degree.