Botanical name: Raphanus sativus

Family: Cruciferae

Origin: Europe

Chromosome number 2n = 18

Inflorescence type – Racemose

Fruit Type – Siliqua

Important Points

• Sporophytic self-incompatibility is present in radish.
• Radish is rich in Vitamin C (15-40mg/100gm)
• The Pusa Chetki variety is suitable for growing in hot months.
• Pusa Himani variety can be grown throughout the year
• Tropical varieties can produce seeds in both tropical and temperate regions.
• The temperate varieties are biennial in nature.
• The pungency in radish is due to isothiocyanates.
• The red colour of the radish is due to anthocyanin pigment.

Nutritive value (per 100 g of edible portion) and use

It has a cooling effect, prevents constipation increases appetite, and is more nutritious when cooked with the leaves. It is recommended for patients suffering from gallbladder problems, piles, liver troubles, jaundice, etc. The juice of fresh leaves is used as a diuretic and laxative.

Varieties

1. European or temperate type
2. Asian and Tropical

The temperate type varieties are smaller in size, less pungent in taste, and are mostly grown as salad crops.

Asiatic Varieties

Climate

Radish is heat tolerant. The ideal temperature for the growth and development of quality roots in radish is 10-15.5°C. The crop is grown in warm climates, with short root varieties producing tough and extremely pungent roots. Bolting intensifies when the day length increases. Long days as well as high temperatures cause the plant to mature prematurely without sufficient roots to form a stalk.

Soil

It can be grown in all types of soil but light sandy or loamy soil is best for radish cultivation. The optimum soil pH range is 5.5-7.0. Heavy soils tend to produce rough, ill-shaped roots with smaller lateral fibers, which reduce market value.

Time of sowing

September-January in the plains of North India

European Varieties: September-March

In the hills: March-October

Seed rate

Asian varieties: 10 kg/ha

European varieties: 12-14 kg/ha

Sowing Method

Radish is sown on ridges. The distance varies with the varieties. The temperate variety gets ready in 25 to 50 days. So they are sown very closely while tropical varieties take longer and are spaced more because of their larger size. Radish is sown on furrows at a distance of 45 cm and at a height of 22 cm. About 1.25 cm from the pointed end of the stick at the top of the ridge. A small furrow is made deep and the seeds are sown by hand in furrows mixed with fine sand or coarse soil. After this, the seeds are covered.

Manure and fertilizers

A fertilizer dose of 25-30 tonnes of well-decomposed cow dung manure and 50 kg Nitrogen, 100 kg P₂O₅, and 50 kg K₂O is recommended for the crop. The full dose of FYM, P₂O₅, K₂O, and half dose of N should be given as the base dose at the time of land preparation. The remaining dose of N is applied at the time of first hoeing.

Irrigation

Give light irrigation immediately after sowing. Irrigate the crop once in 6-7 days depending upon the weather conditions.

Intercultural operations

Weeding, hoeing, and earthing up the field should be done at the right time. Pre-emergence application of Fluchloralin 0.5 kg/ha or Oxadiazon 1.0 kg/ha can effectively control weeds in radish fields.

Digging

Radish should be dug when the roots are tender. A delay of a few days in harvesting, especially of temperate-type roots, may render the pithy and the root quite unfit for the market. European species must be uprooted 20 days after planting before they become spongy and hollow; other varieties are harvested when their roots are still tender and full-sized. To give them a good appearance by pulling them from above by hand, washing them, and removing the soil, they are sent to the market by tying them open in baskets or in bunches of 3-6 according to the variety.

Yield

• The European variety gives a yield of 8000 to 12000 kg per hectare or 5-10 t/ha.
• Asian varieties yield 20,000 to 33,000 kg per hectare or 20–30 t/ha.

Insect

1. Aphid (Lipaphis erysimi, Myzus persicae): Serious pest of radish, attacks at seedling as well as maturity stage. They suck the sap from the soft parts of the plants.

Control

Malathion 50 EC 1ml per liter of water or spray Phosphamidon, Dimethoate (0.05%) two to three times at an interval of 10 days.

2. Mustard sawfly (Athalia lugens proxima): Black larvae feed on leaves.

Control

Spray with Malathion 50EC @ 1 ml/Lit of water. Or spray Phosphomidone or Oxymethyl demeton (0.05%).

3. Flea Beetle (Phyllotreta striolata): Adult feeding on seedling stage and casing small holes.

Control

Spray with Quinalphos (0.05%).

Diseases

1. Mosaic 1: It is spread by aphids. Young leaves develop moulting and interveinal chlorotic areas which gradually increase in size and eventually coalesce to form irregular chlorotic patches.

Control

• Apply Carbofuran @ 1.5 kg/ha to the soil at the time of sowing.
• 2-3 spraying of Phosphomidone 0.05%.

2. White rust (Albugo candida)

Symptoms may first appear as small, pale green spots, which later turn white and eventually develop into raised white pustules like blisters, usually on the lower leaf surface. Systemic infection can occur, causing the tops of young shoots to become distorted and appear abnormally shaped.

Control

• Avoid sprinkler irrigation.
• Follow a 3-year rotation between susceptible crops.
• Grow resistant varieties.
• Spray Mancozeb 2 g/l or Copper oxychloride 2 g/l.

Physiological Disorders

1. Forking/Branching

• It is described as secondary root growth elongation which gives the roots a forked appearance.
• Use of decomposed organic matter
• Presence of high/excessive soil moisture during the period of root development,
• Due to the compaction of the soil, usually, the roots grown in heavy soil are forked.
• Soil with poor physical properties such as large clods of soil and stones under the roots and shallow cultivation lead to forked/branched roots.
• The use of old seeds with low viability or infested with nematode may also lead to the development of forking disorders.
• In addition, closer spacing (45 × 10 cm) also leads to a higher percentage of forking due to increased competition for light, nutrients, and water among plants, which significantly affects plant growth, quality, and yield.

Management

• To prevent this, rotten manure and irrigation should be done in the right amount at the right time.
• Round and short root varieties with rapid root growth should be planted in shallow arable or light soils, while long and large root varieties with poor root elongation should be planted in deep soils.

2. Pithiness

• Pithiness is also known as sponginess.
• It occurs when the accumulation/assimilation of nutrients lags behind the sudden increase in root volume due to sudden growth (thickening), this disproportion in growth results in the development of pores in the roots.
• This can be described as a rapid expansion of root cells with insufficiently accumulated material of parenchyma cells.
• Rupture of xylem vessels in response to strong elongation of root cells is considered to be the first step in pithiness.
• Further, with the development of the root, the size and distance of the cells increase, leading to greater pithiness.
• Later on, the water content in the root cells decreases, and they become spongy.
• Pithiness is the most important limiting factor affecting the post-harvest life of a radish, as it is the last stage of root hollow development.
• When viewed through cross-section the appearance of pithiness roots is a network of white streaks, spots, or loose white tissue as opposed to normal white tissue.
• This is due to the delayed digging of roots.
• In addition, bolting, over-maturity, and excess of nutrients (N, P, K) can lead to root pores.
• Greater spacing (45 × 20 cm) also promotes pithiness as it allows roots to utilize more resources which causes overcrowding and leads to pores formation.

Management

• To avoid pithiness, maintain optimum soil moisture,
• Dig up the roots at the right time,
• Avoid excessive fertilizing, and avoid root injury during intercultural operations and harvesting.
• Both low temperature and high soil EC (salt concentration) reduce growth rates, restricting the development of spongy tissues in the root.

3. Splitting/Cracking

• Cracking is described as root longitudinal fracture, which normally occurs before harvesting or is observed during post-harvest operations (1-2 days after harvest in storage).
• This disorder can be up to 30% and can significantly reduce marketable yield.
• Splitting usually occurs in two ways, one is “cellular debounding” in which the cells remain intact but are pulled away from each other, while in the second type, “plasmolysis”, the cells burst/rupture.
• Radish usually splits due to plasmolysis.
• Cracking in winter radish is due to the difference in expansion rate between the periderm and internal tissues. As the internal tissues expand more rapidly than the periderm, these put pressure on the secondary tissues and cause them to rupture.
• There are many reasons for root split in radish, one of the most important being insufficient irrigation.
• In addition, irrigation frequency and amount affect the water content of the hypocotyl, causing cracks on radish roots during active secondary growth.
• Radish, which was irrigated once in three days, had well-developed hypocotyls and less cracking/splitting incidence as compared to the radish crop which was irrigated once in two, four, six, or eight days.
• In soil, the application of organic fertilizers (70 t/ ha) also leads to split/cracked root development due to high nitrogen concentration.
• Wide fluctuations in temperature (high temperature 35°C) lead to hypocotyl splitting during the later growth period.
• The incidence of cracking is higher in long-rooted varieties, which are rarely cultivated.
• Boron deficiency also appears to be a major factor in inducing hypocotyl splitting.
• In addition, calcium-deficient soil also has a role in the production of cracked roots.

4. Hollowness

• Hollowness is defined as a longitudinally hollow cavity in the center of the root and is commonly seen in summer-grown radish crops.
• Hollowing occurs when the intercellular air spaces in the center (stele) of the root near the pith become fused during the first half of the growth period.
• Conditions favorable to root development such as early summer sowing, high fertilizer application, and low plant density are important in inducing hollowing.
• The faster the roots grow, the more likely they are to become hollow. However, unfavorable growing conditions such as late sowing, high plant density, early defoliation, and low fertilizer rates, which prevent the roots from developing well, result in little or no root hollowing.

5. Internal Browning / Brown Heart / Akashin

• Brown heart or internal browning (IB) is defined as an internal brown/red color in the central region of radish roots, which greatly reduces the commercial value of radish due to its unpleasant appearance and bitter taste, and It is more common in the summer season crop.
• Affected roots appear deformed, small, and brown in colour.
• Plants remain stunted due to a reduction in growth, leaves appear variegated with purple and yellowish-red spots and develop a thick periderm with a brownish appearance in section.
• The outbreak of this disorder is due to the low amount of boron in the soil.
• Boron requirements for radish are higher than for any other crop and a deficiency due to drought conditions or high temperatures can cause internal browning.
• Foliar application of 15-20 kg/ha of Borax and 0.1% B in the soil helps in reducing this disorder.