Effects of selenate applied at two growth stages on the nutrient quality of Cardamine violifolia

Cardamine violifolia is an edible selenium (Se) hyperaccumulator that is mainly distributed in Enshi, China. Here, C. violifolia treated with different selenate concentrations (i.e., 0, 1.5, 20, and 80 μmol L − 1) at the rosette and podding stages in a hydroponic experiment was carried out to investigate the effects of Se accumulation on the nutrient quality of this crop. The shoots accumulated high levels of Se at the rosette and podding stages, and the main Se forms at these stages were selenocystine and selenate. The effects of selenate on the chlorophyll, carotenoid, soluble sugar and protein, total free amino acid, and vitamin C contents of C. violifolia differed between the rosette and podding stages. Selenate treatment reduced total flavonoid and increased the total phenolic acid content at the podding stage. Total glucosinolate content decreased after selenate treatment at the rosette stage. Ten volatile compounds were found in C. violifolia shoots and the dominant volatile observed at the two stages was benzyl isothiocyanate. Selenate treatment demonstrated mixed influences on the volatile compounds. For example, at the rosette stage, selenate treatment inhibited the emission of benzyl isothiocyanate and benzyl isocyanate but promoted the generation of 12,15-octadecadiynoic acid methyl ester. Moreover, selenate treatment reduced the emission of isobutyl isothiocyanate at the podding stage of C. violifolia. These results provide us novel insights into the comprehensive effects of Se on the nutrient quality of Se hyperaccumulators.