Performance of common buckwheat (Fagopyrum esculentum M.) supplied with selenite or selenate for selenium biofortification in northeastern China

Selenium (Se) deficiency commonly occurs in soils of northeastern China and leads to insufficient Se intake by humans. A two-year field study of Se biofortification of common buckwheat supplied with 40 g Se ha−1 as selenite (Se(IV)), selenate (Se(VI)), or a combination (1/2 Se(IV + VI)) was performed to investigate Se accumulation and translocation in plants and determine the effects of different forms of Se on the grain yield, biomass production, and Se use efficiency of plants and seeds. Se application increased seed Se concentrations to 47.1–265.1 μg kg−1. Seed Se concentrations following Se(VI) or 1/2 Se(IV + VI) treatment exceeded 100 μg kg−1, an amount suitable for crop Se biofortification. Se concentration in shoots and roots decreased with plant development, and Se translocation from root to shoot in Se(IV)-treated plants was lower than that in plants treated with 1/2 Se(IV + VI) and Se(VI). Both grain yield and biomass production increased under 1/2 Se(IV + VI) treatment, with grain yields reaching 1663.8 and 1558.5 kg ha−1 in 2015 and 2016, respectively, reflecting increases of 11.0% and 10.3% over those without Se application. The Se use efficiency of seeds and plants under Se(VI) treatment was significantly higher than those under 1/2 Se(IV + VI) and Se(IV) treatments. Thus, application of selenate could result in higher Se accumulation in buckwheat seeds than application of the other Se sources, but the combined application of selenate and selenite might be an alternative approach for improving buckwheat grain yield by Se biofortification in northeastern China.