Rhubarb

Common rhubarb ( Rheum rhabarbarum )

The rhubarb, rhubarb or even vegetable Krauser rhubarb ( Rheum rhabarbarum ) is a crop from the family of the buckwheat family ( Polygonaceae ). The peeled or unpeeled petioles are processed into compote.

Etymology

The name is derived from Middle Rheum rhabarbarum Latin word rheumatic barbarum in the importance of exotic root: root and rheum for barbarus for foreign, alien. The German word barbarian has therefore the same Greek origin as the plant name rhubarb. On his arrival in Europe in the 18th century, the German name from the Italian word was borrowed Rabarbaro, according to the French and the Spanish rhubarbe ruibarbo.

A different version of the dictionary represents Friedrich Kluge: It involves the migration of the plant from east to west. Here, the Persian word rewend as well as a reference to the proper name RHA for the river Volga (Russian Волга ) were transported.

Features

Rhubarb is a perennial plant, forming thick, irregular rhizomes. Above-ground parts die off in the fall. The resting phase begins in August and September. The regrowth in spring with underground buds.

The leaves are in a basal rosette. They are large, three-to multi-lobal. The petiole is up to 70 inches long and 5 inches wide. Depending on the variety, the stem is colored more or less strongly red by anthocyanins. The leaves contain toxins that can cause vomiting when eating raw and circulatory disorders. The leaf margin is slightly curled. The leaf stalks are flat on top, occupied at the bottom round and sharp edges.

The inflorescence shoot is up to two meters high. The flowering occurs between May and the end of June. The cream-colored flowers are in a panicle. For flowering a cold stimulus necessary ( vernalization), the temperatures below 10 ° C for a period of 12 to 16 weeks is required. The flowers are inconspicuous, usually hermaphrodite and are cross-pollinated. The fruits are single-seeded and three-winged achenes. The seed is 7 to 10 mm long, the width is 6 to 8 mm.

After germination rhubarb forms a primary root that develops first into a fleshy, thick beet, which is quite short-lived. The primary shoot developed in the second year of a tuber, in the following years also thicken the lateral axes and there are secondary tubers the meantime grown primary tuber. It caused such a 25-30 thickened stem axis.

History

Rhubarb comes from the Himalayas. In the 16th century it was grown in Russia and arrived in the 18th century in other parts of Europe. About France and the Netherlands, he came to England, where the cultivation is attested since 1753. The forcing was operated first by gardeners in Chelsea and later perfected in Yorkshire. The first commercial production in Germany was in 1848 in Hamburg- Kirchwerder and spread from north to south. In 1937 the area under cultivation in Germany in 1700 acres, 1993, between 350 to 400 acres. Since 1947 rhubarb in the United States is legally regarded as a fruit.

Cultivation

Moderate, deep and well water-holding soils with a pH of 5.6 to 7.2 are best suited for cultivation. The climatic requirements of the rhubarb are modest, he only has a relatively high water demand. The land for cultivation must be free of nematodes and root weeds. Is favorable to the cultivation for a plowing up. After a rhubarb growing a break of seven years must be maintained until the next cultivation. Varieties differ mainly by inner and outer stem color, growth length, stem thickness and time of sprouting and harvest.

Rhubarb is grown with or without foil cover in the field and in rooms as forcing. Propagation is mainly vegetatively by division of rhizomes. About In- vitro propagation on Plant tissue culture virus-free plants can be obtained.

In the field, the first harvest takes place in the second year after setting. The culture usually takes five to six years. Here the end of May only be harvested to about, in the following years until the end of July. The manual harvest for the fresh market is often carried out every eight to 14 days, harvesting for the processing industry often only twice per season. The young inflorescences are dropped when harvesting the leaves to increase the yield. The yields can reach 20 to 45 tons per hectare market goods. Under appropriate conditions, 0 to 1 ° C and 90 to 95 percent relative humidity, to outdoor rhubarb can store up to three weeks. Rhubarb is sensitive to ethylene and must therefore be stored air-permeable.

Rhubarb is forced in greenhouses or in buildings. The optimum conditions for this are 12 to 16 ° C and 85 to 90 percent relative humidity. The rhizomes are turned this into loose soil. The expulsion at light leads to the preferred red color of the stems. In England Rhubarb is traditionally driven under special clay pots.

Use

The petioles are - depending on the variety and age of sticks - peeled and cut most processed. Rhubarb is considered because of its preparation commonly referred to as fruit, although he is one of the vegetables. The best-known compositions are jams and compotes, both on an industrial scale, as well as cakes. In addition, rhubarb is also processed into juice or must. Rarely, rhubarb is used as a vegetable. Popular Rhubarb is because of its refreshing, spicy -sour taste and low calorie content.

Ingredients

The petioles contain an average of 94.5 grams of water per 100 grams of edible fresh matter. The 1.3 g of carbohydrates were divided fairly evenly on glucose, fructose, sucrose and starch. In addition, 0.6 g protein, 0.1 g fat and 3.2 g of fiber are included. At minerals 270 mg potassium, 50 mg calcium, 25 mg phosphorus, 13 mg of magnesium and 0.5 mg of iron in 100 g contain. At vitamins are vitamin C 10 mg, vitamin A ( carotene) with 0.07 mg, vitamin B1 with 0.025, 0.030 and B2 Niacin 0.25 mg to call. The energy value is 54 kJ (13 kcal).

Important for the taste of the fruit acid, especially malic and citric acid, in combination with the sugar. Varieties with red meat contain less fruit acids than those with green flesh. The variety " Ras Versteeg " contains about 1.5 grams of malic and citric acid 0.1 grams per 100 grams of edible fresh matter. In the stems 460 milligrams of oxalic acid per 100 grams fresh weight are included in the average. This high content is a powerful human calcium- wracking. For kidney and gall sick as well as for children with caution.

The laxative effect of rhubarb is probably due to the anthraquinone, which stimulates peristalsis. Medically the roots of Rheum palmatum are mostly used, not the vegetable rhubarb.

Diseases and Parasites

Economically significant is the rhubarb mosaic disease, which is caused mainly by the Arabis mosaic virus ( arabis mosaic virus ) and the carbon black ring virus ( turnip mosaic virus ). Thus, the intercostal fields of the leaves turn yellow in April / May. Also important are the nematodes, especially Stängelälchen ( Ditylenchus dipsaci ), beet eelworm ( Heterodera schachtii ) and root- ( Meloidogyne naasi ). Leaf beetle, aphids and caterpillars do not usually lead to reduced yields.

Varieties

  • Timperley Early
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