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Radish

 Contents

I.          Introduction

II.         Soil

III.        Climate

IV.        Varieties

V.         Planting Requirements

VI.        Manures and Fertilizers

VII.       Irrigation

VIII.      Interculture

IX.        Pest Control

X.         Disease Control

XI.        Harvesting and Yield

XII.       Storage and Marketing

Preface

Radish is one of the choicest salad vegetables grown all over the world. Its green leaves are a rich source of vitamin A and can also be used as green leaf vegetable. It is a quick growing vegetable, thus, occupying field for a very short period. Also, it is equally suitable for growing in large scale as well as in kitchen or nutrition gardens.

 I. Introduction

Radish is a popular vegetable in both tropical as well as temperate regions. It is cultivated under glass house conditions for i early market, but large scale cultivation in the field is more I common. Being a quick growing crop it can be easily planted as a companion crop or intercrop between the rows of the other vegetables. It can also be planted on ridges, separating one plot from another. It is cultivated all over India, especially near the city markets.

Radish originated probably in China. In India, it seems to have been cultivated from ancient times. It was popular among the ancient Egyptians and Greeks.

The botanical name of radish is Raphanus sativus. The enlarged edible roots are fusiform and differ in colour from white to red. There are two distinct genetical groups in radish. The Asiatic varieties, which are primarily for tropical climates, produce edible roots in the first season and seed in the second season as a biennial crop. On the other hand, the exotic or European varieties produce roots in the plains of tropical and subtropical climate and seeds in the hills of temperate climate.

 II. Soil

Radish can be grown on nearly all types of soils, but the best results are obtained on light friable loam soil that contains ample humus. Heavy soils produce rough, mis-shapen roots with a number of small fibrous laterals and, therefore, such soils should be avoided.

 III. Climate

Commonly radish is a cool season crop but the Asiatic varieties can resist more heat than the European or temperate varieties. It attains best flavour, texture and size at 10 to 15°C. Long days as well as high temperature lead to bolting without adequate root formation. During the hot weather, the root becomes tough and pungent before reaching the edible size and, therefore, crop should be harvested while young and small in size. The radish is more pungent at higher tempcrature. Pungency decreases with cooler temperature.

IV. Varieties

A large number of varieties indigenous as well as introduced, are cultivated in the different regions of India. The indigenous varieties are usually white with a conical shape, attaining 25-40 cm in length and are said to be more pungent than the introduced European types. European types are not very common and popular in India. Important characteristics of some of the recommended varieties are given below.

I. Pusa Desi

It is a tropical and subtropical cultivar suitable for growing from middle of August to October in the northern plains. Roots are pure white, 30-35 cm long, tapering with green stem, pungent and heavy yielder. It matures in 50-55 days after sowing.

2. Pusa Himani

The roots of Pusa Himani are 30-35 cm long and 10-12 cm in girth with green stemend. They are scmi-stumped to tapering with short stalks. The skin is pure white and the flesh is soft and sweet flavored with mild pungency. Though it is primarily a variety for hilly region, it has been found to do well in milder climate of the plains also.

 

3. Pusa Chetki

It has been developed at IARI, New Delhi. Roots are medium long, white, good textured, weighing 300 -400 g each. Since it can tolerate high temperature, it is suitable for sowing from the middle of March to middle of August. This cultivar sets seeds properly in the plains because it bolts very early in the plains during October- November. It yields about 200 -250 quintals fresh radish per hectare.

 4. Pusa Reshmi

The roots are 30-45 cm long with white green tinge on top. It is suitable for early sowing during winter, but it can tolerate slightly higher temperature. Good sized roots are ready for harvesting in about 55 to 60 days.

 5. Arka Nishant

This variety has been developed at IIHR, Bangalore. It matures in 45 -55 days. Roots are medium sized, marble white, crisp texture, pleasant aroma, free from early bolting, pithiness, splitting and forking. Each root weighs about 300-400 g. It is pungent and yields about 200 -300 quintals of fresh radish per hectare.

 6. Japanese White

It has been developed at IARI, New Delhi. The roots are cylindrical, 22 -25 cm in length and 5 cm in diameter. The skin is snow white, flesh crisp, solid and mildly flavoured. It matures in 45 days.

It is suitable for growing between October and December in plains and during July to September in hills.

7. Punjab Safed

Radish roots are white tapering, smooth, mild in taste, free of forking, 30 to 40 cm in length and 3 -5 cm thick. It is a quick growing type.

 8. Kalyani White

Roots are pure white with blunt end, uniform in size, 25 -30 cm length. It is a mildly pungent cultivar with light top. It can be grown throughout the year except a few months during the summer. It takes about 45-50 days to reach edible maturity.

 9. Chinese Pink

The skin is shining red, and the flesh is white, crisp, solid and mildy pungent. The roots are 30-40 cm long with a semi-blunt end.

The top is medium. It is a good cultivar for the hills but can be grown in plains with mild climate. It requires low temperature for secd production.

I0.IHR-I-I

Roots are thin, about 30 cm long, frec from premature bolting, pithiness, splitting and forking. Roots are mildly pungent, each weighing about 300 gm. Root surface is smooth, shining and white. It is highly resistant to white rust and takes about 45 days to reach harvesting maturity.

 11. Rapid Red White Tipped

It is an extra European type which matures in 25-30 days. The roots are smooth, small, round and bright red with white tip.  Flesh is pure white, crisp and snappy.

 12.White Icicle

It is a medium -short European variety which matures in 30 days. The skin is pure white, thin and tender, whereas the flesh is icy-white, crisp, juicy, mild and sweet flavoured with just enough, pungency to appeal the appetite. The root is a solid icicle shaped straight and tapered. It has given a good harvest in the plains.

V. Planting Requirements

Radish is sown by seeds. Important aspects of sowing such as land preparation, sowing time, seed rate, seed treatment, and seed sowing methods are describes here.

1. Land preparation

The soil for radish is thoroughly prepared so that there are no clods to interfere with root development. The soil should not contain any undecomposed organic matter because that may result into forking of roots or mis-shapen roots. Generally first ploughing, about 30 cm deep, is done with soil turning plough and remaining 4-5 ploughings are done with desi plough. Each ploughing should be followed by planking. Application of well decomposed farmyard manure should preferably be done at the time of first ploughing.

2. Sowing time

Since radish is a cool season crop, its cultivation is prepared during winter season in the plains. It can be sown at any time between September and January in northern plains as it is not affected either by frost or by extreme cold weather condition. It is grown from March to August in the hills. In the regions where summer is mild, it can be grown throughout the year, except few months of summer. In Bangalore, radish roots are available for 8-10 months of the year but the best edible roots are available during November-December only. The temperate types are generally not planted till October.

 3. Seed rate and seed treatment

Radish seeds count about l00-125seeds per gram. About 9-12 kg seed will be sufficient for sowing in one hectare of land. It has been found that soaking radish seeds in naphthaline acetic acid (NAA) at. 10-20 ppm before sowing is effective in stimulating germination of radish seeds.

4. Method of sowing

Radish is usually grown on ridges to facilitate good root production. It is grown, as a single crop or as a companion crop. The plant rows or ridges about 22 cm high are kept about 45 cm apart, whereas the plants within the rows are kept 8 cm apart. The European or temperate types, as they need closer spacing, can be sown 20 -30 cm apart. Generally the seed sowing is done 1.15 cm deep. Seed is sown by any of the two methods namely line sowing and broadcasting.

 a. Line sowing

Seed is mixed with sand or soil in the ratio of 1:4 and placed in a row by hand, over the ridges and then covered with Soil.

 b. Broadcasting 

Seed is mixed with sand or soil in ratio of 1:4 and scattered over the field, as even as possible, followed by planking. Plants are spaced after germination while hoeing.

VI. Manures and Fertilizers

Radish is a quick growing crop, hence the soil should be highly rich in plant nutrients. Add farmyard manure 25-40 tonnes, nitrogcn 18-50 kg in the form of ammonium sulphate, phosphorus 50 kg in the form of superphosphate and potash 50 kg in the form of muriate of potash for one hectare of the field.

The farmyard manure should be mixed up thoroughly at the time of field preparation, whereas the complete doses of potassic phosphatic and one half dose of nitrogenous fertilizers can be applied in the rows before sowing. The remaining half dose of  nitrogenous fertilizers should be applied as a top dressing along with irrigation when the plants start growing vigrously.

VII. Irrigation

It is necessary that enough of soil moisture is available to help uniform seed germination and growth of the plant. If sufficient soil moisture is not available at the time of sowing, the first irrigation is given immediately after sowing. It is advantageous in case of light soils but it hinders the germination in heavy soils. In such soils, the surface becomes dry with hard film formation before the seed  sprouts. In this case it is always safer if the sowing is done when already enough of soil moisture is available for germination. Depending upon the season and the soil moisture availability, radish may be irrigated once or twice a week. It should not be irrigated very frequently, but care should be taken that field does not become dry and compact and the root development is not checked.

VIII. Interculture

Regular weeding is necessary to check the growth of the weeds. During rainy season, two weedings will be required to keep the growth of weeds under check. Tok E -25 (Nitrofan 25%) applied as pre-emergence, controls both monocot as well as dicot weeds in radish field. One earthing up and one weeding during the early stages of growth are necessary for proper development of roots. Radish has a tendency to bulge out of soil as it grows in size. Therefore, thorough covering by earthing up is recommended to produce quality roots. For seed crop, a second earthing up during flowering and fruiting is advocated to prevent lodging of the plants.

IX. Pest Control

The common pests of radish are described below.

1. Aphids

Aphids are the most serious pests of radish. They attack both seedlings and mature crops. Cloudy humid weather conditions favours the spread of their infestation. In case of heavy infestation the plants are completely devitalized, leaves and shoots curl up, become yellowish and finally die.

Control

Spraying Malathion 50% in the ratio of one litre in 1000 litres of water gives sufficient high percentage of kill with a residual effect of 2- 3 weeks. Nicotin sulphate one litre in 800 litres of water is also effective at higher temperature of about 210 C. Spraying Nuvacron (1.25ml) or Metasystox (2ml) per litre of water is also recommended.

2. Mustard saw-fly

This is a common pest of radish and turnip. In radish, it appears when the crop is in flowering and at vegetative stage. The damage is done by the group by biting holes in the leaves and fruits.

Control

Mustard saw-fly can be controlled by dusting 10% BHC at the rate of 15-20 kg per hectare at the vegetative growth of the infested crop and 35-40 kg per hectare at the seed formation stage. Spraying of 4 gm Sevin 50 W.P. per litre of water at weekly interval can also control this pest.

 3. Flee beetle

In some areas, it becomes a serious pest on the vegetative parts of the plants which are eaten by this pest.

Control

It can be controlled by spraying with Malathion (0.15%) or Sevin (0.4%) at 10 to 15 days interval.

X. Disease Control

Radish develops so quickly and the entire period of culture, even of a seed crop, is so much short that the crop matures before any slow developing disease can show its serious effects. Some of the important diseases of radish are black rot, alternaria blight, crown, gall disease, white rust, downy mildew, white mosaic and radish  phyllody. These diseases are described here along with their suitable control measures.

1. Alternaria blight

This disease is caused by Alternaria raphonic. Symptoms usually first appear on the leaves in the form of yellowish, slightly raised I spots or Iesions. These lesions enlarge many times on seed pods. Infection spreads rapidly during rainy weather, and the entire food may be so infected that the styler end becomes black and shriveled. The fungus penetrates the pod tissues ultimately infecting the seeds. The infected seeds may lose their viability.

Control

Use of disease free seeds is the prime requirement. Spraying of the crop with fungicides is recommended if seeds are being produced or if the vegetable crop is of high value. In the latter case spraying should be done only in the early stages of plant growth. Copper oxychloride (0.5 to 0.75%), Maneb (0.2%), or Zineb (0.25%) or Blitox 50 can be used as spray. Two to three sprayings will be sufficient.

 2. White rust

White rust of radish is caused by Albugo candida. In some areas, the disease assumes a serious problem of radish. It produces a white powdery substance in patches on the under surface of the leaves. It mainly appears on the leaves and flowering shoots which get deformed and bear only malformed flowers.

Control

Destruction of diseased crop debris helps in reducing the inoculum. Weed control and other sanitary precautions are also essential. Among fungicides 0.8% Bordaux mixture or Dithane Z- 78 (0.3%) can be sprayed for the effective control of the disease.

3. Downy mildew

This disease is caused by the fungus Peronospora parasitico . In addition to radish, the fungus also attacks cauliflower, cabbage, turnip, etc. The disease is characterized by the appearance of the purplish brown spots on the under surface of the leaves. These spots may remain small or enlarge considerably. The upper surface of the leaf above the lesion is tan to yellow. Downy growth usually appears on the under surface of these lesions.

Control

Crop rotation, clean seed beds, destruction of weed and other sanitary measures are important to check the spread of the disease. Intensity of the disease can be reduced by spraying 0.2% Maneb, 2-3 times at 10 days interval after the disease has been noticed in the field.

 4. Black rot

This disease is caused by the bacterium Xanthomonas compestris. It effects almost all the cruciferous plants all over the world. It is a seed-borne disease. The plant may be affected at any time during its growth from the youngest seedling until it matures. On young seedlings, the cotylcdons are affected at the margins which show blackening and such cotyledons die. Later, infection of leaves occurs through water pores at the margins. The infected tissues I turn yellow and the chlorosis occurs. The veins show a brown or black discolouration.

Control

The pathogen lives only for one year in the field, hence two years crop-rotation is sufficient to check the soil borne infection. For seed treatment a number of antibiotics such as Agromycin (0.01 %), Streptocycline (0.01%), Agromycin, ete. are available. One of the recommendation is to give hot water treatment at 520 C for 30 minutes. Application of 10-12 kg stable bleaching powder per hectare as soil drench is also effective.

5. Radish mosaic

It is a viral disease. The symptoms first appear as small, circular to irregular chlorotic lesion in between and adjacent to the veins. Little or no leaf distortion is noticed, and stunting or abnormal leaf formation rarely occurs. Severe yield loss in susceptible cultivars of radish is caused due to this viral disease.

Control

The disease can effectively be checked by controlling aphids with insecticides and weed hosts by spraying weedicides.

6. Radish phyllody

It is a disease of radish seed crop which appears at the time of flowering. The sepals, petals and carpels of the affected flower show the phyllody condition and stamens become sepaloid. The degree of phyllody increascs in the direction of carpels.

So far no suitable control measures have been evolved for this discase.

 XI. Harvesting and Yield

Depending upon the cultivars, the roots become ready for harvesting in about 25-35 days after sowing. Early and rapid maturing European cultivars reach harvest maturity in 25-30 days after sowing. They become bitter and pithy if the harvesting is delayed. In India, harvesting is done manually. A light irrigation may be given before harvesting to facilitate lifting of roots. In advanced f countries, commercial radish growers use a single row harvester  that pulls the plants from the soil, cuts the roots from the tops, then places them in bags for transportation to a picking shed. The Asiatic improved varieties produce 150-250 quintals roots per hectare in 40-60 days, whereas the European or temperate varieties produce 80 -100 quintals roots per hectare in 25 -30 days.

XII. Storage and Marketing

After harvesting, the roots are properly washed, graded and tied in bundles. They can be put in wooden baskets and sent to markets early in the morning. Radish roots cannot be stored for more than 2 -3 days under room temperature. However, they can be stored for about two months in, cold storage at 0oC temperature with 90 -95% relative humidity.

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Please note that this is the opinion of the author and is Not Certified by ICAR or any of its authorised agents.