a group of plants with tubers on the underground stems or on the side roots that are used for food, for fodder, or in the manufacture of raw materials. Root crops are generally native to the tropics and belong to various families. The potato of the family Solanaceae and the artichokes of the family Compositae have tubers that develop from the stems. The sweet potato of the family Convolvulaceae and the cassava of the family Euphobiaceae have root tubers. The tubers of most root crops store carbohydrates, predominantly starches (up to 19 percent in potatoes, 24–28 percent in sweet potatoes, and 35 percent in cassava) or inulin (up to 12 percent in artichokes). They also contain protein, fat, and vitamins. The most important root crop in temperate zones is the potato; in the tropics, the sweet potato and the cassava. Root crops are propagated from tubers or cut pieces of tubers with developed buds, seeds, and cuttings (parts of the stems).
V. N. VEKHOV
plants grown for the sake of their large, succulent underground organs (incorrectly themselves called the root crops).
The root crops comprise primarily biennial plants of the families Cruciferae (turnip, charlock, rutabaga), Umbelliferae (carrot, parsley, celery, parsnip), and Compositae (chicory, viper’s-grass). There are, in addition, some annuals, such as garden radish, and perennials, such as sea kale (family Cruciferae). Most root crops develop a rosette of leaves and the enlarged root during the first year of growth. The upper part, or head, of the enlarged root bears the rosette and is formed of the shortened stem. Below this is the neck, consisting of the hypocotyl—the part of the stem between the cotyledons and the primary root (for example, in carrots) or the upper part of the primary root (for example, in beet, turnip, or rutabaga). The root proper (usually meaning the primary root of the shoot) branches into lateral roots. The mass of the enlarged root is composed of thickened parenchyma of the xylem (in charlock and turnip) or of the phloem and skin (in carrots). In beets, the growth ring of xylem and phloem is formed by several rings of cambium; nutrients are stored in the parenchyma. In the second year, buds located in axils of the rosetted leaves develop into a flower-bearing and seed-bearing stem. The plant dies after fertilization.
Root crops demand moisture. Good harvests are obtained on fertile, loose soils. Root crops contain many sugars, mineral salts, vitamins, and carotenes. As foods, root crops are used boiled, stewed, and raw. They are also dried and canned.
L. V. KUDRIASHOV