Shoot mineral composition and yield of wheat genotypes grown on a sodic and a non-sodic soil

A collection of wheat lines including 49 overseas and 35 Australian lines was grown in a 3-replicate randomised block design experiment at 2 sites (Two Wells and Roseworthy Campus, South Australia) during the 1994 growing season (June-December 1994). The aim of this investigation was to determine if elemental nutrients could be implicated in response to soil sodicity tolerance of wheat. Large grain yield differences and mineral concentrations were evident among different varieties including those from Australia. Several mineral concentrations in shoot, including manganese, potassium, sodium, phosphorus, boron, zinc and copper, taken up by these plants were correlated significantly with grain yield. The detrimental effects of sodium and boron concentrations on grain yields were less for local varieties than the overseas lines, because of lower average shoot concentrations and lower coefficients of variation associated with the Australian varieties. The grain yield reduction at a sodic site appeared to be due to both soil physical changes and nutritional changes, with the combined effects of nutrient deficiencies and toxicities accounting for 23% of the variation. Except for the large differences of boron and sodium concentrations, there appeared to be a similar magnitude of variability between the overseas wheat collection and the Australian wheats. The present study confirmed that the tetraploid and hexaploid wheats differ in sodium concentration or potassium:sodium ratio, in addition to other nutrient changes including potassium, manganese, magnesium and copper. However, sodium concentration (or potassium:sodium ratio) and boron were not sufficient enough to explain the variability in grain yield of all the Australian wheats studied, suggesting that other factors detrimental to wheat production in sodic soils need to be identified.