Radish : Raphanus sativas L.
Radish (Raphanus sativus L), which originated from Europe or Asia, is presently cultivated all over the world. In Sri Lanka, Radish is one of the vegetables that can be grown in all agro ecological regions through out the year if adequate moisture is available. Two varieties, Japan ball Rabu and Beeralu Rabu are recommended for upcountry and low country respectively. Long and red/spring radishes that are mainly used for salad and decorative purposes have high demand for hotel industry. In addition, radish is used for pickling and other processing industries. Radish is widely cultivated in the districts of Nuwaraeliya, Badulla, Kalutura and Galle. Among other districts where it could be successfully grown are Kandy, Matale, Gampaha and Ratnapura.
Radish is used as vegetable or salad in Sri Lanka. The major component in the edible portion of radish (per 100g) is water that amounts 94.5%. Further, it contains protein, fat, carbohydrate, fiber and ash, which account 1.0, 0.1, 306, 0.7 and 0.8 grams respectively. The vitamins and minerals (100g) that consists in radish are follows
Source: Department of Food and Nutrition, American Medical Association, Futura Publishing Co.1974.
Varietal characters of recommended varieties
1. Japan ball
Roots - Round, white skin
Leaves - lobed to mid-rib pubescent
Harvest time - 45-55 days
2. Beeralu rabu
Roots - Spindle shape, white skin
Leaves - neither lobed nor pubescent
Harvesting time - 45 -50 days
3. Table radish
Roots - Marble size, red can be eaten raw
Harvesting time - 35-40 days
Radish can be grown in all agro ecological regions
Well drained soils with a pH range of 6.0 - 7.5 is more suitable
Soils should be ploughed to a depth of 30-40 cm to provide fine tilth
Unlike other exotic vegetables, seeds of radish could be produced under local climatic conditions
A radish crop should be isolated from other radish crops by the following
Basic seed crops- 1600 m; Standard seed crops- 1000m. If any species
of wild radish or mustard are found within the isolation distances during
flowering, the seed crop will be rejected.
2. Time of planting - Mid November
3. Spacing - 1' - 1 ' X 1' - 1 '
Basic seed production - Harvest the tubers 4-6 weeks after planting and transport the uniform tubers of the harvest for seed production.
Standard seed production
i. Non uniform plants should be roughed out before flowering stage to maintain the purity of the variety.
ii. At flowering stage, rough out the non uniform plants according to the colour of flowers
Standard colour of the petals
Beeralu - Purple and white
Japan ball - Mostly white. Some times white and purple
The popular varieties Japan Ball Rabu and Beeralu Rabu are widely cultivated by the farmers in the Up country and Low country respectively. The private sector, farmer organization and the farmers are the major source of seed supply. Department of Agriculture is supplying the total demand of Basic seed of Beeralu Rabu while seeds of Ball Rabu is imported by various private companies. Seeds of all the other varieties (Long and Red radish) available in the market are also supplied by the private sector.
Seed Requirement & Source of supply of Radish - Beeralu & Ball during 1998-2002.
Time of planting
In upcountry, only during March to May and August to October to avoid flowering
Planting and spacing
i. Dibble in rows on raised beds
ii. Spacing - 25-30 cm between rows; 10cm between plants
iii. Spacing for table radish - 20 cm X 5 cm
iv. Plant 2 seeds per hill and thin out one at germination
Basal ( At planting)
i. Urea -90kg/ha
ii. Tri super phosphate - 110 kg/ha
iii. Muriate of potash - 65 kg/ha
Top dressing ( 3 weeks after planting)
i. Urea - 90 kg/ha
ii. Muriate of potash - 65 kg/ha
Irrigate daily for the first 4-5 days; then every 3-4 days depending on rainfall
One hand weeding 4 weeks after planting for the up country and 2 weeks after planting for the low country
Major pest and disease control
Swelling/ malformation on the main root and laterals
Leaf eating caterpillars
Control: Apply chlorofluazuran, Quinalphos, Profenophos, Eteofenprox or neem seed water extract
Vegetable leaf miner - Liriomyza huidobrensis
On foliage, larvae makes on lower leaf surfaces and usually are associated with the midrib and lateral veins. A mine usually begins on the upper leaf surface and moves to the lower surface after a few millimeters of feeding by the larva. Adults punching leaves for both feeding and oviposition. Punctures and mines may be numerous enough to greatly reduce photosynthesis and may kill young plants. These mines and punctures further reduced the value of ornamental plants.
Inspection of the fields before and after cultivation of the crop is needed for the proper management of the Liriomyza huidobrensis. Knowledge on cropping pattern and distribution pattern of the leaf miner in the region is important to achieve successful management of this pest.
Inspection of crop
Diglypus isaea, a hymenopteran parasitoid was introduced in 1998. At present this it is well established in the region. Later, two local hymenopteran parasitoids, Hemiptarsenoideus semiabiclavus and Opius spp. were identified. However introduced parasitoid is showing more than 80% of the parasitism compared to two other parasitoids in the region.
Cutworms - Agrotis spp. and other Noctuidae species
They are the larvae of several noctuid moths species that cut through the stems of young plants. Robust and grayish larvae as long as 5 cm remain buried at the base of the plant during the day. Roots closer to the ground surface may suffer occasional damage. Some species wil preferably feed on the leave.
Spotted or localized field infestations are typical, calling for focused insecticides treatments and it should be applied at the base of plants at dusk
Harvesting & post-harvest technology
Japanese ball - 40-50 t/ha
Beeralu - 20-30 t/ha
Harvesting should be done at proper time. Delay in harvesting reduces the quality of radish by accumulating high amount of fibrous
Extents and Production
Extent and production of Radish cultivation during 1991- 2002
District wise extent and production
The District wise estimated extents and production for 2000/2001 Maha, 2001 Yala and 2001/2002 Maha are given in Table. The districts of Nuwara Eliya, Badulla, Matara, Moneragala, Ratnapura, Kandy, Kurunegala, Kalutara, Galle and Hambantota will be the major contributors to the total production in the future.
District wise Extent and Production during 2000/2001 Maha, 2001 Yala and 2001/2002 Maha.Source: Based on DOA task force report, 1998
Only small quantities of radish are exported mainly to Middle East countries
(Source: Customs department, 1997).
Labour (73%) is the highest cost component in radish cultivation, follows with seed (18%), pesticide (6%) and fertilizer (3%) (Source: Department of Census and Statistics, 1996). The unit cost of production for the period of 1998-2001 is given in Table. The estimated production cost indicates that increasing the productivity of the crop by adopting appropriate technologies could reduce the unit cost of production.
Estimated cost of production (COP) for Radish during 1998-2001.
(Assumed cost of production of 30,700 Rs/ha & Average produces price of 4.12 Rs/kg)
Cost of Production
Labour (73%) is the highest cost component in radish cultivation, follows with seed (18%), pesticide (6%) and fertilizer (3%) (Source: Department of Census and Statistics, 1996).
Adoption of following strategies could reduce the production cost
Quality improvement for Export
Uniform shape, length (> 15 cm) and width (6-8 cm) with white skin color are the requirements for export market. In addition, the skin should be free of blemishes, physical injuries and pest and disease damages. Usage of proper varieties, adoption of appropriate management practices and pre and post harvest handling improve the quality of produce for export market.
Increase in productivity, total production, percapita consumption, extent under cultivation and demand and volume for export are the progress indicators for the expansion of radish cultivation.
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