Beetroot or garden beet (Beta vulgaris) is a popular root vegetable grown for its fleshy roots, which are used as cooked vegetables, salad, and for pickling and canning. It belongs to the family Chenopodiaceae (now Amaranthaceae) along with chard and spinach. Both leaves and roots are edible in beetroot. The leaves have a bitter taste whereas roots are sweet. Typically, rich purple in color, beetroot can also be white or golden. The green leaves are a rich source of calcium, iron, vitamin A and C. Beetroots are an excellent source of folic acid, and a very good source of fiber, manganese, and potassium. Beetroot is gaining popularity as a new superfood owing to recent studies claiming that its juice improves athletic performance, lowers blood pressure, and increases blood flow. Beetroot-based new products especially juices, drinks, etc., are coming up and are preferred by consumers due to their nutritional value.
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Beetroot is biennial, producing a fleshy elongated hypocotyl and a rosette of leaves in the first year and flowers in the second year. The upper portion of the fleshy root develops from hypocotyls and the basal part from taproot. Concentric rings are seen in the cross-section of the root are due to alternate formation of vascular tissues and storage parenchyma tissues. Root skin color varies from orange-red to dark purple-red. The color of beetroot is due to the presence of red-violet pigment of ß cyanin and yellow pigment of ß xanthin.
One gram of seed ball counts about 50 seeds, which retain its viability for 5-6 years under ordinary storage conditions. Attempts to breed varieties with monogerm seeds are in progress since thinning is a costly and essential operation in beetroot cultivation. Beetroot is an important crop for low inputs and high yield from a small cultivated area.
Climate and soil requirement for Beetroot Cultivation
Beet is less sensitive to heat, requires sufficient daylight, and has low wind sensitivity and less water requirement. Thus, it can grow in almost every climate. Being fairly hardy, it is generally considered a cool-weather crop. Although beet grows in warm weather, it usually attains better color and quality when produced under cool and moist conditions. In India, it grows best during winters in plains. It requires abundant sunshine for proper development. Beetroot is most productive at 20-22°C. Where summers are hot, it is produced as early spring, fall, or late winter crop. It grows well during warm sunny days and cool nights. It can be grown in the mild climate of hills around the year. Although it is biennial in nature, if the plants are subjected to a relatively low temperature of 4.5-10°C, over a period of 15 days or longer, some plants start bolting (formation of flower-stalks) in the field before attaining marketable size. Temperature above 26°C can make roots hard having less sugar content. Good quality beet grown in cool weather has a high sugar content and dark internal color flesh. Under unfavorable conditions, beet shows alternate white and colored circles when sliced. This zoning of beet is more prominent in hot weather.
Beetroot thrives best in light to medium-heavy soil. Loamy sand, deep, well-drained, and fertile soils are preferred for this crop. Quality beet is produced on a wide variety of soils, but slightly alkaline soils (with a pH up to 8.0) are ideal. A loose, rich loamy soil is desirable for producing shapely roots, the lighter soils, however, are good for early crops and the heavier for the main crop. Muck soil is excellent for late beet crops since it is loose and moist.
Varieties of Beetroot
The choice of cultivar is influenced by days to maturity, foliage size, root shape and size, exterior surface smoothness, interior color, and degree of zoning. On the idea of the form of roots, the beetroot varieties are classified as flat, short, top-shaped, round or globular, half long and long. The varieties recommended for cultivation are globular or round-shaped. However, a couple of other varieties of which seeds are imported are also cultivated for domestic use. The recommended varieties for cultivation are given here.
Crimson Globe: Its tops are medium to tall, leaves elliptical large and bright green with maroon shade, although venation is prominently colored in young and older ones. Edible roots are globular to the flattened globe, medium red with little shoulders. Roots are early, sweet, and tender, valuable for canning and pickling. The flesh is dark red, with hardly any zones, and non-corrosive in taste when eaten raw. This is a heavy yielder (>200 q/ha) and suitable for salad-making and for juice propose.
Crosby Egyptian: Roots are flat globe with a small taproot and a smooth exterior. The internal color is dark purplish red with some indistinct zoning. The top is medium tall, green with red veins. The cultivar reaches maturity in 55-60 days after sowing and shows pronounced white zoning when grown in warm weather.
Detroit Dark Red: Its tops are small, leaves are glossy dark green, with maroon tinge (more prominent in older ones). Venation is prominent, midrib is thin from the dorsal side and appears to be wider because of the maroon shade around it. Roots are perfectly round with deep red skin, tender, firm, crisp, top to round shape with a tap root, showing hardly any zones. The flesh is deep red, fine-grained, tender, and corrosive when eaten raw, but exceptionally sweet when boiled. It gives an average yield of 150-200 q/ha. It is suitable for salad and juice purposes.
Early Wonder. The roots are a flattened globe with round shoulders a smooth dark red skin. The interior is dark red with some lighter red zoning. The top is heavy, green with red veins. The cultivar takes 55-60 days after sowing to reach harvestable maturity. Ooty-1: It has round roots with blood-red flesh color. It matures in 120 days from seed sowing. The marketable yield of roots ranges from 250-300 q/ha. It sets seed under Nilgiris conditions.
Other varieties: Madhur, Ruby Queen and Ruby Red are a few of the varieties marketed by the private seed industry.
Cultivation Practices in Beetroot Cultivation
Planting of Beetroot
Proper soil preparation is a key to the success of best root production. An ideal beetroot bed needs deep, rock-free soil. Its seeds are sown directly, spaced between lines at 35-45 cm when cultivating on ridges and 30-40 cm on flatbeds. Plant spacing of 10-15 cm within the line is maintained by thinning. The seed should be sown on ridges 2-2.5 cm deep in fields having sufficient moisture. The irrigation should be done taking care that seeds are not washed away from ridges. Raised beds are preferred as they serve the purpose of subdividing large fields into small plots to facilitate irrigation. Raised beds provide deep, friable soil that the root crops require, stay warmer than ground beds (enabling the seed to germinate readily) and allow excess water to drain rapidly. The ideal spacing for commercial beetroot production is 45 cm x 10 cm. A seed rate of 7.5-8 kg is required to raise a crop on 1 ha. Sowing in high hills (>1,200 m) is carried out from March to April and June to August; in mid-hills (800-1,200 m) from February to March and July to September, and in plains September to November.
For continuous availability, sowing at 2 weeks intervals provides its roots regularly. To get better germination, seeds are soaked in water for 5-12 hr depending on the temperature. Uniform germination takes place when the beds are not too moist or too dry. Seed balls are placed in the soil in close contact by compacting. High moisture causes damping off. Raking is done to break the crust as seeds sprout poorly in crusted soil. A germination inhibitor in seeds may be removed by soaking them in water for 2-4 hr before planting.
Training and pruning in Beetroots
The top of the beetroots after attaining a fair size can be pruned or thinned to be used as greens. Thinning at 5-10 cm distance by pulling the young plants to be used as potherb is always beneficial.
Manuring and fertilization in Beetroot Cultivation
All the root crops need potassic fertilizers in plenty as these help in root development. Its growth being rapid, application of 100:50:70 kg NPK/ha is recommended for normal soil conditions. A basic dose of 25 tonnes/ha of well rotten farmyard manure or compost at the time of soil preparation is beneficial. If organic manure is applied, the application of NPK can be reduced. The application of 60:40:50 kg NPK/ha is sufficient to obtain optimum roots. A full dose of P and K and one-third of N may be applied as basal dose. Second and third doses of N may be applied as topdressing 5 and 7 weeks after sowing. If the soil is poor in micronutrients, a good micronutrient combination can be used.
Aftercare in Beetroot Cultivation
Weeds in and between the rows, in the field must be removed. They should be controlled by hand weeding or hoeing. Frequent shallow cultivation should be done at regular intervals to keep the crop weed-free and facilitate soil aeration and proper root development. Early weeding is critical in any root crop. If early weedings are not done a good crop of beets cannot be taken. Chemical weed control in beet fields may be practiced. Pre- and post-emergence sprays of propachlor (2.5 kg/ha) give weed control for 40-50 days and increase the yield of roots. Hand thinning of seedlings when they are 6-8 cm tall is very important since each fruit or seed ball contains more than one seed and the plants come up in clumps, thinning is done until individual plants are 8-10 cm apart. When the roots are 2.5 cm in diameter, pull every other one of the row, water well, and mulch to keep down weeds and conserve moisture. These uprooted young plants are required by processors and green leaves can be used as a potted herb.
Irrigation in Beetroot Cultivation
Irrigation time is very important. If rain is not sufficient, irrigation at 7-10 days intervals is ideal. In the cultivation of beet deficiency of water may lead to a reduction in size. The water requirement of beet is about 300 mm to be applied in 5-6 irrigations. If there are winter rains only 3 irrigations are sufficient for the growth. Assured irrigation with 2.5 cm water a week should be given otherwise plants bolt and the roots crack or become stringy and tough. The key to a sweet-tasting beet is even soil moisture and rapid growth. Soil should be kept moist throughout. If the soil dries and water is added it causes root splitting.
Yield and quality of Beetroot
A foliar application of growth substances for increasing yield, quality, and pigment content has been suggested in beetroot. Application of tyrosine (100 ppm) and proline (200 ppm) proved beneficial in improving the growth and yield characters of beetroot. Beetroot growers can effectively use these two amino acids as a foliar application to increase yield for edible purposes and to increase pigments for extraction to be used in coloring and medicinal industries. the average yield of beet varies from 250-300 q/ha.
Seed production in Beetroot cultivation
Unlike the other root crops, annual tropical types do not exist in beetroot. All cultivars varieties in beetroot are temperate biennial types and seed production is possible in hills beyond 1,400 m above mean sea level. A low temperature of 4.4-7.7°C for 6-8 weeks is required to initiate flowering. The usual method of seed production is the root to seed method. In this method, seeds are sown in July-August and well-developed roots are dug out during November-December. After the selection of root, the top is trimmed without injuring the crown. For producing elite seeds, stecklings or roots are selected for their true shape and checking of the internal color by cutting a V-shaped nick 1.5-2 cm deep vertically on one each side of the selected root depending upon root size. Thus, dark-colored roots without zoning are selected and replanted for producing a commercial seed crop. The whole roots of selected plants are transplanted at a spacing of 60 cm x 45 cm in well-prepared and irrigated fields. Harvesting is done during June-July. Being a cross-pollinated crop, that is too wind-pollinated, an isolation distance of 1,000 m is required to be kept for certified seed production and 1,600 m for breeder and nucleus seed production. The average seed yield is 15.0 q/ ha.
Physiological disorders in Beetroot cultivation
The internal black spot or brown heart or breakdown of beets is caused due to the deficiency of boron (B) in neutral or alkaline soils. Hard and corky black spots are scattered throughout the root but are always found in the light-colored zones. The light-colored zones are the youngest cells of beet that are actively growing. Its deficiency affects young cells and tissues first. The younger leaves of the plants tend to be more strap-like than the older leaves or may become malformed and one-sided in shape. Detroit Dark Red variety of beet shows comparatively fewer symptoms of B deficiency. Borax if applied @ 11.2 kg/ha in soil, checks its deficiency symptoms. If seeds are sown early and the temperature is high, beetroots produced are often coarse with woody flesh and dull in color. If too much fresh manure or compost is added shortly before planting or growing in rocky or heavy soils, poorly formed, hairy roots develop.
Harvesting and post-harvest management in Beetroot cultivation
Early beets are pulled from rows when they are about 3.5 cm in diameter. If beets are allowed to grow much larger, they become woody, spongy, especially in warm and dry weather. Beets for bulk marketing or canning are topped in the field when they attain a diameter of 6.5-8 cm. Beets can be kept in polybags under cool, and moist storage conditions. The best time to harvest beets is on a dry clear day. Deterioration of beets starts if roots are left for more than 10 days after attaining the full size. For harvesting of roots, the soil should be somewhat moist to remove roots easily. Harvested roots can also be tied in bunches of 4-6 each according to their size but all roots should be fairly uniform.
Healthy and clean beetroots are often stored in outdoor pits or in a common storage house. The best temperature of beets to store well is 0°C and 90% relative humidity, but roots should not be allowed to freeze. The air in the storehouse or cellar should be kept humid to prevent wilting and withering of roots. Beetroots can also be stored in pits 90-150 cm deep. The length and width of the pit depend upon the number of roots to be stored. Before storing, the pit should be dry. It is filled with topped roots, after that, a layer of dry soil (30 cm) is put above roots. This is covered with dry grass and finally by polythene to protect it from moisture, rain, snow, or low temperature. Thus, beetroots can be stored for 4-6 months. The washed beetroots in a plastic bag can be stored for 2 weeks in the refrigerator.