EFFECT OF PHOSPHATE FERTILIZERS ON THE ELEMENTAL COMPOSITION OF SEED OF WHEAT, LUPIN, AND TRITICALE

The effect of phosphorus (P) fertiliser applications applied to the soil on the composition of up to 15 elements (N, P, K, Ca, Mg, S, Cu, Zn, Mo, Mn, Ni, Co, Cd, Fe, and Se) in the seed of wheat (Triticum aestivum), lupin (Lupinus angustifolius), and triticale (x Triticosecale) was measured. The seed was grown in six field experiments in south-western Australia, where P fertiliser was applied as single superphosphate, triple superphosphate or rock phosphate. Two of the experiments compared wheat and lupin, two were only wheat, one was lupin, and one was sown to triticale. The P fertiliser levels were applied either one to three years previously or while sowing the crops that produced the seed. Basal fertilisers (some or all of the following depending on the site: N, K, S, Ca, Mg, Cu, Zn, Mo, Mn, and Co) were applied before sowing the crops to ensure that P was the only element limiting yield. Increasing the levels of P fertilisers applied to all species increased the concentration of P and K in the seed. P concentration increased by 20 to 200% and K concentration by 13 to 20%. There was one exception for K; in one experiment the concentration of K in the seed of wheat did not change. For the other elements, increasing the level of application of P fertiliser either had no effect on their concentration in the seed, or the concentration increased or decreased. Generally Ca, Mg, Zn, Fe, and Se did not change, but Cu decreased. Sulfur was unaffected in cereals but increased in lupin. N was, unaffected in lupin, but in cereals, when it did change, it decreased. When Mo, Mn, Ni, Co, and Cd changed in cereals, they increased, with the exception of Ni, which decreased for triticale. Nickel and Cd also increased in lupin but Mo and Mn decreased and Co did not change. The concentration of N, K, Ca, Mg, S, Zn, Mo, and Ni was always higher in lupin seed than in wheat or triticale seed whereas the concentration of Mn was lower in lupin seed. The sources of P used to grow triticale in one experiment affected the concentration of certain elements. At equal seed yields, seed grown using triple superphosphate had a greater seed concentration of P, K, Mo, Mn, and Ni than seed produced using either of the two rock phosphates. Queensland rock phosphate produced higher concentrations of Cu, Mn, Ni, and Co than North Carolina rock phosphate, but a much lower concentration of Cd.