Yield, Quality, Antioxidants and Elemental Composition of New Leek Cultivars under Greenhouse Organic or Conventional System

Abstract

A. porrum is known due to its high antioxidant activity and the ability to accumulate significant amount of potassium and iron. We assessed yield, quality indicators, antioxidants and elemental composition of nine leek cultivars grown in greenhouse under organic or conventional system in Moscow region. The farming system did not affect yield, which attained the highest value with the cultivar Giraffe and the lowest with Premier and Cazimir. Pseudo-stem dry matter and sugars were favourably affected by organic management, whereas nitrate concentration was enhanced by conventional farming. The cultivars Vesta and Summer breeze showed the highest dry matter and total sugar content, whereas Goliath had the highest antioxidant, selenium and potassium concentration. Among the antioxidants, ascorbic acid attained higher values with the organic management. The antioxidant system of A porrum was characterized by highly significant positive correlations between: Se and polyphenols, Se and ascorbic acid, Se and K, ascorbic acid and polyphenols, ascorbic acid and K, polyphenols and K (r = 0.94, 0.94, 0.95, 0.94, 0.95, 0.96, respectively, at P ≤ 0.001). Negative correlations were recorded between leaf and pseudo-stem Se and between leaf and pseudo-stem polyphenols (r = −0.922 and −0.976 respectively, at P ≤ 0.001). Among the mineral elements, only K was significantly affected by the farming system, showing higher content in organically grown pseudo-stems. Intervarietal differences in pseudo-stem element composition showed strong positive correlations of: Al with As, Co, Li, Pb and V; Cr with I, Mg, Si, Ca; V with As, Co and Fe; negative correlations of Se with Cr and I. Compared to related specie such as A. sativum, A. porrum accumulated equal to garlic levels of K, Mg, P, Cd, Cu, Mn, Se, Zn, lower levels of Si and significantly higher amounts of Ca, Na, Al, As, Cr, Ni, Pb, Sr, V, Sn, B, Co, Fe, I, Li. The strong relationships between quality, antioxidant and mineral components in leek plants may give wide possibilities in breeding programs under both conventional and organic system.