Effects of selenium application on biochemical characteristics and biofortification level of kohlrabi (Brassica oleracea L. var. gongylodes) produce.

Background: Biofortification of vegetables with selenium (Se) greatly depends on species tolerance to Se supply. Due to the scant information regarding kohlrabi Se biofortification, the aim of the present work was the evaluation of foliar sodium selenate application on yield and biochemical characteristics of three kohlrabi cultivars. Material and methods: A two years field experiment was conducted in Moscow region (Russia) on 3 kohlrabi cultivars using foliar biofortification with Na2Se04 solutions (50, 75 and 100 mg/L) and subsequent biochemical analysis of roots, stems and leaves. Results: Out of the three concentrations tested (50, 75 and 100 mg/L) plus an untreated control, the Se 75 dose demonstrated the strongest growth stimulation effect resulting in the increase of stem weight (by 1.35-1.61 times), yield (1.37-1.66 times), monosaccharide (1.59-2.24 times), ascorbic acid (1.54-2.01 times) and total phenolic levels (by 1.23-1.37 times), compared to the untreated control. The biofortification values varied from 69.4 (White Vienna 1390) to 59.9 (Dobrynya F1 hybrid) and 43.6 (Sonata F1 hybrid) under the Se dose of 100 mg/L. The maximum Se content in kohlrabi stems reached 4.40 mg/kg d.w. for Sonata F1, 3.53 mg/kg d.w. for Dobrynya F1 hybrids and 5.20 mg/kg d.w. for cultivar White Vienna 1390. Significant correlations were revealed between Se and total phenolics (0.720; p < 0.002), ascorbic acid (0.842; p < 0.001), monosaccharides (0.898; p < 0.001) and total sugar (0.764; p < 0.001). No significant changes in nitrate levels and dry matter content were recorded as the result of Se supply. Conclusion: The outcomes of the present research demonstrated the high benefits of Se application in improving kohlrabi yield and nutritional quality.