Genetic differences in the copper nutrition of cereals. II.* Genotypic differences in response to copper in relation to copper, nitrogen and other mineral contents of plants

Abstract

Cereal genotypes differed considerably in their sensitivity to copper deficiency. Copper concentrations in the leaves and grains were determined to see whether they reflected the copper status of plants. Nitrogen, phosphorus, calcium, zinc and manganese in the grains from normal plants were determined and the interrelationships between the mineral-accumulating ability of genotypes and their sensitivity to copper deficiency were examined. Copper concentration in the shoot at mid-tillering, when copper deficiency may be recognizable, clearly distinguished severely copper-deficient plants from copper-sufficient ones. In deficient plants, the mean concentrations of copper in the youngest leaves and older leaves were <1.0 and <2.0 ppm respectively. However, after maturity, copper concentrations in flag leaves and grain did not reflect the copper status of the plants. Nor did the content and distribution of copper in the plants explain the differential sensitivity of genotypes to copper deficiency. Accumulation of nitrogen, phosphorus, calcium, zinc, manganese and copper in the grain varied between genotypes. Nitrogen and phosphorus concentrations in the grains of normal plants were related to the differential responses of genotypes to copper. Evidence shows that the cereal genotypes with higher grain protein contents are potentially more susceptible to copper deficiency than those with relatively lower grain protein. ____________________ *Part 1, Aust. J. Agric. Res., 27: 453 (1976).