Effects of soil properties and fertilization on quality and biological activity of Swiss chard

Swiss chard (Beta vulgaris L. var. cicla) is a leafy vegetable highly consumed in many parts of the world as a very popular ingredient of different diets. The purpose of this study was to evaluate effects of soil properties and fertilization on yield, mineral composition, total phenolics, antioxidant and biological activity of Swiss chard. The mineral composition of Swiss chard was generally affected by soil properties. The fertilization at 50% of recommended level (110 kg ha(-1) N, 90 kg ha(-1) P2O5, and 100 kg ha(-1) K2O per season) affected negatively yield and on the other hand affected positively antioxidant activity, while fertilization at 150% of recommended level had a contrary effect. The available K in soil affected the yield positively. Total phenolics were in negative correlation with the yield. The positive relationship of total phenolics and content of Mn in chard was noticed. The greatest efficacy in human colorectal carcinoma cell lines was obtained by Swiss chard extract from plants fertilized at 150% of recommended level.