Beta vulgaris (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Beta vulgaris L.

Protologue: Sp. pl.: 222 (1753).

Family: Chenopodiaceae

Chromosome number: 2n= 18

Major taxa and synonyms

• Cv. group Garden Beet: B. vulgaris L. convar. crassa (Alef.) Helm provar. conditiva (Alef.) Helm (1957), B. vulgaris L. ssp. vulgaris convar. vulgaris var. vulgaris sensu Mansfeld (1986), B. vulgaris L. ssp. vulgaris sensu Ford-Lloyd (1986).

• Cv. group Spinach Beet: B. vulgaris L. convar. vulgaris provar. vulgaris sensu Helm (1957), B. vulgaris L. ssp. vulgaris convar. cicla (L.) Alef. var. cicla sensu Mansfeld (1986), B. vulgaris L. ssp. cicla (L.) Koch sensu Ford-Lloyd (1986).

• Cv. group Swiss Chard: B. vulgaris L. convar. vulgaris provar. flavescens DC sensu Helm (1957), B. vulgaris L. ssp. vulgaris convar. cicla (L.) Alef. var. flavescens DC sensu Mansfeld (1986), B. vulgaris L. ssp. cicla (L.) Koch sensu Ford-Lloyd (1986).

Vernacular names

Cv. group Garden Beet (cultivars grown for the swollen hypocotyl and root):

• garden beet, beetroot (En)
• Betterave potagère (Fr)
• Indonesia/Malaysia: bit
• Philippines: remolatsa (Bisaya)
• Thailand: phakkat-daeng (central), phakkat-farang (Bangkok)
• Vietnam: cải dường, củ dền.

Cv. group Spinach Beet (cultivars grown for the leaves):

• spinach beet, leaf beet (En)
• Poirée à couper, poirée ordinaire (Fr)
• Indonesia: bit bodas.

Cv. group Swiss Chard (cultivars grown for the enlarged petioles and midribs):

• Swiss chard (En)
• Poirée à carde, carde, côte de blette (Fr).

Origin and geographic distribution

Wild forms of B. vulgaris occur along the shores of the Mediterranean, extending eastwards as far as Indonesia and westwards along the coasts of the Atlantic up to southern Norway. B. vulgaris was taken into cultivation in the eastern Mediterranean or the Middle East and first mentioned in the literature in Mesopotamia in the 9th Century BC. It followed the early trade routes to East Asia, reaching India in classical times and China by 850 AD. Originally, beets were grown mainly for their leaves. The first recorded recipes for the root date from the 3rd Century AD. Towards the end of the Middle Ages the garden beet, with its thick cylindrical or globular root, had become an important vegetable in central Europe. Very little is known of the development and early distribution of Swiss chard. Presently, beets are grown for their roots, petioles and leaves throughout the world. Garden beet is the most important form worldwide.

Uses

The usually deep-red roots of garden beet are eaten boiled either as a cooked vegetable, or cold as a salad after adding oil and vinegar. A large proportion of the commercial production is processed into boiled and sterilized beets or into pickles. Spinach beet leaves are eaten as pot herb. Young leaves of the garden beet are used similarly, e.g. in Indonesia and Japan. The midribs of Swiss chard are eaten boiled like asparagus.

Roots and leaves are used medicinally against infections and tumours, and garden beet juice is a popular health food. Betanins, obtained from the roots, are used industrially as red food colourants, e.g. to improve the colour of tomato paste. Forms with strikingly coloured, large leaves are grown as ornamentals.

Production and international trade

Europe and North America produce the bulk of the crop and their combined annual commercial production amounts to 900 000 t (excluding Eastern Europe). Spinach beet is important in northern India and parts of South and Central America, but no production figures are available. In most other areas beet crops are grown mainly for home consumption or local markets.

Properties

Garden beet contains per 100 g edible portion (80% of the fresh root): water 89 g, protein 1.5-2.0 g, fat 0.1-0.2 g, carbohydrates 7-10 g, fibre 1-1.5 g, ash 1 g. The energy value is 160 kJ/100 g. The carbohydrates consist purely of saccharose. Compared with other vegetables, garden beet has a low mineral and vitamin content. Spinach beet, in contrast, has less energy value but is richer in vitamins and minerals. The nutritional value of Swiss chard is intermediate between Garden beet and Spinach beet.

The colouring agents in garden beet are not anthocyans, but heterocyclic nitrogen compounds: red betacyanins (betanins). Beets contain geosmin, which causes the typical earthy smell.

1000-seed weight is 5-10 g. Seeds are normally clustered into glomerules or seedballs. The weight of 1000 seedballs is 13-22 g.

Description

• A highly variable, robust, erect, usually biennial herb.
• Main root long, stout, tapered, side-roots forming a dense, extensive root system in the top 25 cm of the soil. In garden beet, the hypocotyl and the upper part of the main root are conspicuously swollen, being globular, flattened, cylindrical or tapering; adventitious roots occur in two opposite rows on the lower part; the swollen root consists of alternating layers of strongly coloured conductive tissue and light coloured storage tissue. In vegetative plants leaves grow in a basal rosette and have long petioles.
• Leaves alternate, often ovate and cordate, 20-40 cm long, margins wavy except in spinach beet, leaf tissue puckered between nerves, subglabrous, green, dark green or red, often shiny; leaves in the inflorescence passing into linear bracts; in Swiss chard the petiole and midrib are swollen.
• Inflorescence a long, paniculate, more or less open spike, 50-150 cm long; flowers greenish, sessile, bisexual, usually 2-3(-5) together, subtended by minute bracts; perianth 5-partite, becoming thicker at base as fruits ripen; stamens 5; ovary 1-celled, surrounded by a disk; pistil short with 2-3 stigmas.
• Fruit 1-seeded, enclosed within the swollen corky perianth-bases, 3-7 mm in diameter, 1-6 fruits adhering in groups called glomerules or seedballs.
• Seed kidney-shaped, brown, 1.5-3 mm in diameter and 1.5 mm thick.

Growth and development

Beets are biennial plants requiring vernalization for flower induction. In cultivars of temperate areas 4-10 °C for 2 weeks is sufficient to induce flowering. The low-temperature requirements in tropical selections are less. Long daylengths further promote flowering. Flowering in garden beet is also stimulated by high temperatures, which may lead to flowering during the first year in the tropics. This risk does not occur in Swiss chard and spinach beet. When grown for seed production, flowering can be obtained by using vernalized seed or seedlings. Pollination is mainly by wind, though flowers produce nectar and are visited by insects, especially thrips. Beets are selfincompatible.

Other botanical information

At present it is quite generally accepted that the cultivated taxa of the genus Beta L. all belong to one species: B. vulgaris L. However, there is disagreement concerning the infraspecific classification and the classification of related wild taxa, together constituting section Beta of the genus Beta. There are almost no barriers to gene exchange between the wild and cultivated taxa and a pattern of continuous morphological variation is present.

In the literature the subclassification of B. vulgaris is confused and characterized by numerous ranks and names. As long as the phylogeny of the cultivated taxa is not known with certainty, it seems most appropriate to classify the cultivated taxa below species level only in cultivar groups and in cultivars, as has been done here. In this view, the other two cultivated Beta taxa, sugar beets and fodder beets, should be classified as B. vulgaris L. cv. group Sugar Beet and B. vulgaris L. cv. group Fodder Beet, respectively.

For the vegetable types, some cultivars recommended for the tropics are:

• cv. group Garden Beet: "Crimson Globe" and "Detroit Dark Red";
• cv. group Spinach Beet: no specific cultivars are known; all sold planting material is called spinach beet;
• cv. group Swiss Chard: "Fordhook Giant" and "Lucullus".

The most recent revision of the wild Beta taxa within section Beta distinguishes 3 species: B. vulgaris L. (with ssp. adanensis (Pamukçuoglu) Ford-Lloyd & Williams, and ssp. maritima (L.) Arcangeli), B. macrocarpa Gussone and B. patula Aiton.

Ecology

Temperatures over 25 °C adversely affect growth and colour development of garden beet. An elevation of 600-1000 m in the tropics is the minimum for profitable production. Spinach beet and Swiss chard tolerate higher temperatures.

Beets require a fertile, moist soil for good growth. They prefer a neutral to slightly alkaline pH. As they originate from sea-shores, they are tolerant of limited concentrations of salt.

Propagation and planting

Beets are always propagated by seed. Seed production in the tropics is difficult and seed is normally imported. Beets are sown 2-3 cm deep in rows (12.5-)25-30(-50) cm apart. Mostly, whole seedballs are sown, making thinning to single plants necessary. Monogerm seed, obtained through breeding or by dividing the seedballs, is available. As transplanting may give poor results and malformed roots, beets are often direct-seeded. However, Chinese gardeners normally transplant. The plant density depends on the purpose of the crop. For young, high quality minibeets the plant spacing may be as close as 12.5 cm × 5 cm, whereas for a crop of mature garden beets the plant spacing may be 25 cm × 10-13 cm. Spinach beet and Swiss chard are planted 5-25 cm apart, depending on the system of harvesting.

Husbandry

Relatively large amounts of fertilizer are important for profitable yields. Nitrogen can be given as NaNO₃ in slightly acidic soils, or where available Na is limited. In some areas common salt is applied as a fertilizer or sprayed to stimulate beet growth and to kill small weeds. Where boron deficiency causes stunted and slow growth, 10-30 kg/ha of borax can be applied. However, too much boron may be toxic to the subsequent crop. For good growth, moist soil is required. Irregular irrigation may cause cracking of roots.

Diseases and pests

Beets are generally not seriously attacked by diseases or pests. Downy mildew (Peronospora parasitica) transmitted by seed may cause red-rimmed spots on the leaves of adult plants. Another leaf disease is Cercospora beticola. Phoma betae, also transmitted by seed, may cause damping-off, as do Pythium and Rhizoctonia.

Larvae of beet web worms feed on leaves and produce webs. Occasionally aphids and beet leafminers are a problem. Meloidogyne root knot nematodes affect the roots of beets.

Harvesting

Garden beets are often harvested with their leaves and tied into bunches of 3-4 and sold fresh. Harvesting is often by hand, but various kinds of mechanical root harvesters can be used. The time from planting to harvesting depends on the size of the roots preferred. Minibeets with a diameter of 3-4 cm can be harvested about 2 months after sowing, full-size beets after 3-4 months.

Spinach beet and Swiss chard are usually harvested by cutting the large, still vigorous, outer leaves with a knife. Harvesting can start about 45 days after sowing and can continue for up to 2 years in fertile soil. In closely spaced plantings, whole plants are sometimes harvested.

Yield

With good cultivation techniques and effective weed control garden beet in the tropics may yield 15-25 t/ha. Swiss chard and spinach beet may yield 100 t/ha per year though much higher yields have been obtained under small-scale intensive cultivation.

Handling after harvest

Garden beet can be stored for more than half a year under cool, well-ventilated conditions, provided the leaves are removed. The optimum temperature is 0-4 °C at a relative humidity of 90-95%. Industrially, beets are preserved after steam-boiling and skinning and addition of vinegar, either as whole minibeets or sliced.

Genetic resources

Genetic material collected for breeding work in sugar beet and fodder beet can be used in breeding vegetable beets. Collections of wild and cultivated Beta material from the eastern Mediterranean and secondary centres of diversity are kept by sugar beet breeders in Western Europe and North America. The genus Beta has a high priority for IBPGR since diversity is rapidly eroding.

Breeding

Most breeding work is done in temperate countries, but also in southern China, Hong Kong and northern India. Breeders of garden beet aim at rapid root formation, limited leaf production and petioles narrow at their base, good homogeneous colour, good shape, appearance and taste, and no bolting in the first year.

Prospects

Spinach beet and Swiss chard, with their high productivity and high nutritional value, merit more attention as market vegetables in the cooler parts of the tropics. Garden beet is mostly grown for the European cuisine. The absence of serious diseases and pests and the good transport and storage characteristics are commercially attractive.

Literature

• Knott, J.E. & Deanon Jr, J.R. (Editors), 1967. Vegetable production in South-East Asia. University of the Philippines Press, Los Baños, the Philippines. pp. 290-292, 305-317.
• Krug, H., 1991. Gemüseproduktion [Vegetable production]. 2nd edition. Verlag Paul Parey, Berlin, Germany. pp. 287-294.
• Letschert, J.P.W., 1993. Beta section Beta: biogeographical patterns of variation and taxonomy. Thesis. Wageningen Agricultural University Papers 93-1, Wageningen, the Netherlands. 154 pp.
• Messiaen, C.-M., 1974. Le potager tropical [The tropical vegetable garden]. 2. Cultures spéciales [2. Special crops]. Presses Universitaires de France, Paris, France. pp. 374-379.
• Nonnecke, I.L., 1989. Vegetable production. Van Nostrand Reinhold, New York, United States. pp. 347-353, 500-504.
• PAGV, 1988. Teelt van kroten [Cultivation of beetroot]. Teelthandleiding No 24. Proefstation voor de Akkerbouw en de Groenteteelt in de Vollegrond (PAGV), Lelystad, the Netherlands. 51 pp.
• Tindall, H.D., 1968. Commercial vegetable growing. Oxford University Press, United Kingdom. pp. 119-122.

Authors

• L.P.A. Oyen