The effects of sodium selenate applications on growth and selenium concentration in wheat

Abstract

In two field experiments, one located on a silt loam and the other on a clay loam, sodium selenate was applied to ‘Rongotea’ wheat sown in late autumn at rates which supplied 5, 10, 15, and 20 g Se/ha, as a seed coating, prills drilled with the wheat seed, or a foliar spray at mid-tillering and/or ear emergence. At both experimental sites, application of sodium selenate caused small reductions in vegetative growth and grain yield, but improved Se concentrations in mature plants and their fractions, viz straw, grain, wheaten flour, milling residue, and bran. Selenium concentrations in mature plants were linearly and significantly related to the quantities of sodium selenate applied. Each method of application was effective in raising Se concentrations, however, late foliar applications of sodium selenate made at ear emergence were slightly more effective than either the earlier foliar applications at mid-tillering, or the seed coating or prills treatments. Increases in plant Se concentrations were 32% greater on the silt loam than on the clay loam. Concentrations of selenium in wheat grain and wheaten flour sufficient for normal health in livestock and humans were achieved by applications of sodium selenate which supplied approximately 10 g Se/ha. © Crown 1989.