Assessment of Content of Fat and Tocopherols in Seeds of Amaranthus in Relation to Diversified Fertilization with Macroelements
This study is based on the field experiment carried out in the years 2007-2008, on an individual farmer's field in Bodaczow, near Zamosc. The aim of the experiment was to determine the influence of different dosages of NPK on the content of fat and homologous tocopherols in the seeds of two varieties of amaranth: Rawa and Aztek. The experiment was started on brown soil made from loess, with high content of P, K and Mg, and slightly acidic reaction (pH in l mol KCl·dm-3 - 5.8). The experiment was started with split-plot method in three repetitions, and involved: two varieties of amaranthus (Rawa and Aztek), and 4 variants of fertilization with macroelements NPK (kg · ha-1) (1 - object without any fertilization, 2 - 70 N, 50 P2O5, 50 K2O; 3 - 90 N, 60 P2O5, 60 K2O; 4 - 130 N, 70 P2O5, 70 K2O). The content of fat was marked in the seed with Soxhlet's method, and α-, β-, γ- and Δ-tocopherol with high performance liquid chromatography (HPLC). The study reveals that the amount of accumulated fat in the seeds of amaranthus largely depended on the variety of the plant and variant of fertilization with macroelements. Significantly high content of fat in the seeds was found at the fourth (the highest) level of fertilization with NPK. Higher content of fat in the seeds was determined in Aztec variety than Rawa. The varieties of amaranthus varied considerably in the content of: α-, β-tocopherol and their total amount. Higher content of α-tocopherol and its higher total amount was found in the seeds of Aztek variety, rather than Rawa. The seeds of Rawa variety had significantly more β-tocopherol than Aztek variety. Fertilization with growing dosages of NPK had a significant, positive influence only on the amount of α-tocopherol and its total amount.
Biotic and Abiotic Factors Affecting the Content of the Chosen Antioxidant Compounds in Vegetables
Vegetables are a rich source of biologically active substances, which support the body's defense mechanisms. A large group of these substances are compounds with antioxidant properties. Apart from vitamins (A, C and E), tocopherols, carotenoids, glutathiones and thiocyanates, polyphenols are also classified as the compounds of antioxidant properties being found in plants. They include: phenolic acids, flavonoids and hydroxycinnamic acid and among them a large group of anthocyanins. These compounds inhibit DNA damage in cancer cells, induce the production of insulin in the pancreas and protect the human brain from aging. They have also high antioxidant activity, which determines the defense mechanisms of plants under stress, such as temperature varia-tions, UV radiation, attacks by pests and mechanical damage. Their content may vary among individual plants of the same species, which is associated with a number of internal and external conditions, such as genetic factors, environmental and agronomic. The contents of anthocyanins determines plant species, botanical variety and breeding and biological processes associated with ontogenesis. Also climatic and soil factors, the factors influencing the content of antioxidants and agronomic factors such as method, place and date of planting, fertilizing, mulching, salinity may contribute to the formation of stress conditions during plant growth and increase the content of antioxidants in plants. This review focused on the content, composition, and antioxidant capacity of vegetables.