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Leek (Allium porrum) is known for its high antioxidant activity and the ability to accumulate significant amounts of potassium and iron. We assessed yield, quality indicators, antioxidants and elemental composition of nine leek cultivars grown in greenhouses under organic or conventional systems in the Moscow region. The management 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 higher with organic management, whereas nitrate concentration was higher with conventional management. The cultivars Vesta and Summer Breeze showed the highest dry matter and total sugar content, whereas Goliath had the highest antioxidant, selenium and potassium concentrations. Among the antioxidants, ascorbic acid attained higher values with organic management. The antioxidant system of leek 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 management system, showing a higher content in organically grown pseudo-stems. Varietal 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 species such as garlic (A. sativum), leek accumulated levels equal to garlic 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 for both conventional and organic management systems in greenhouses.

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The beneficial synergism between selenium (Se) and other antioxidants on human health stimulates the search of new medicinal plants with high antioxidant activity (AOA) and Se accumulation levels. Using fluorimetric method of Se analysis and titrimetric method of total AOA determination monitoring was achieved of 53 species of herbs, 24 species of deciduous and evergreen trees and shrubs and 11 species of conifers grown on the Southern and SouthEastern coast of the Crimean peninsular. Two new Se-hyperaccumulators were indicated among deciduous trees: Tamarix ramosissima and Paliurus spina-christi with leaves Se content 6236 and 1800 µg. kg-1 d.w. respectively. Among herbs 5 new hyperaccumulators were revealed: Artemisia draсunculus cv. Izumrudny, Anthemis tranzscheliana, Cota tinxtoria, Astragalus arnacantha and Limonium gerberi with Se accumulation levels of 23460, 9479, 960, 4110, and 1926 µg. kg-1 d.w. respectively. Medians of Se levels reached 97 µg. kg-1 for conifers, 86.5 µg. kg-1-for deciduous plants and 61 µg. kg-1-for herbs with the appropriate AOA values: 67, 70. and 49.3 mg-GAE.g-1 d.w. respectively. Tamarix was the only plant with both Se hyperaccumulation abilities and high AOA level (212 mg-GAE. g-1 d.w). High AOA (188-256 mg-GA E. g-1 d.w) and relatively high Se levels (193-236 µg. kg-1) were demonstrated for Pistacia atlantica and Cotinus coggygria.

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