Radish (Raphanus sativus L.) is annual, and it is biennial too, and it belongs to the family Cruciferae or mustard family. The origin of radish is said to be China and middle Asia. For fresh markets and in kitchen gardens, radish is a very popular vegetable crop. Generally, a cool-season crop grows well under temperate conditions. Radish roots are consumed as raw as salad and cooked like a vegetable. In ancient days radish is used as in the preparation of medicine for liver and gall bladder ailments
Verities and hybrids of radish:
Rapid red white-tipped
Like most of the other vegetable crops, radish cultivation is possible in various kinds of soils. However, a deep, well-drained, friable, and alluvial soil will give crop with the best quality. Humus content in the soil and the soil’s ability to retain moisture in it are things that need to be remembered in radish production. Heavy soils and sandy soils should be avoided as they are not suitable for radish production. Even though radish cultivation is possible in a wide range of soils, it does well under slightly acidic soils.
Even though it is a cool-season vegetable, radish is able to tolerate warm temperatures. At temperatures between 10.0 and 15.5°C, we can get good quality produce. Pungency will increase in temperature before it reaches to the marketable maturity. At elevated temperatures, roots will attain a repulsive flavor and become more fibrous and mature early. Temperature requirements will change from variety to variety. So, the selection of a variety for a given location is the most important factor in obtaining the best quality roots. It bolts under long days with high temperatures.
In radish propagation is done by seeds, in field seeds are sown either by dibbling, x, broadcasting, or dibbling. Radish seeds will be brown to reddish-brown in color; it weighs around 100 seeds per gram. Radish seeds will remain viable for several years. It takes around 4 -6 days to germinate at 20°C. staggered sowing can be done to get a continuous supply of roots.
The seed rate of radish is around 10 – 12 kilograms per hectare for temperate types and it is 8 – 10 kilograms per hectare for tropical types.
As the seeds of radish are directly sown in the field, land should be thoroughly prepared to provide proper conditions which are optimum for germination of radish. Field preparation should be done by repeated plowings, harrowings, and leveling until getting a fine tilth. The field should be kept clean by removing weeds, the debris of previous season crops, etc.
In the plains, radish cultivation is possible almost throughout the year except during the summer season, as the roots produced in that period will be very pungent, lack pleasant flavor, and be of poor quality compared to the roots produced in other seasons. Roots of radish can be continuously supplied over a longer period by staggering planting at intervals of 10-15 days.
Radish seeds are usually sown in ridges, which are 30 – 45 cm apart. A distance of 7.5-10 cm is recommended for this crop between plants to plant. Two or three seeds can be sown per hill in order to ensure that at least one will get germination. In the case of the drilling method of sowing, sowing is done in rows at 30-45 cm apart. Seeds need to be mixed with sand or ash to make sowing easy.
The seedlings need to be thinned after the completion of germination, and the desired plant population needs to be maintained.
Manures and fertilization:
Radish fertilizer requirements are high compared to the other root crops as it is a heavy feeder. Particularly it requires high amounts of nitrogen and potassium. However, these fertilizer requirements will change from variety to variety, depending upon the type of soil, etc. A variety that yields around 20 tonnes will require around 120-kilo grams of nitrogen, 65 kilograms of phosphorous and 100-kilo grams of potash. It is suggested that farmyard manure should be used after proper decomposition; otherwise, it may cause forking of roots by making soil hard.
Time of fertilizer application:
The entire dose of FYM needs to be applied during the time of land preparation so that it will thoroughly mix with the soil. Apart from that, half of the nitrogen and the entire dose of phosphorus and potassium need to apply during the time of sowing, whereas, the remaining dose of nitrogen need to apply after the seedlings have emerged completely.
Light irrigation should provide soon after sowing to ensure proper germination of the seeds. During the summer season, irrigation should be provided at every 4- 5 days intervals, whereas in winter, it can be extended up to 10 – 15 days. In the rainy season, regular irrigation is not necessary.
In the early stages of the growth, the field should be kept free from weeds by regular weeding and hoeing. While carrying out intercultural operations, care should be taken to avoid damages to the growing roots.
Earthing up needs to be done one month after germination in case of long-rooted verities to encourage proper root growth.
As it can be grown in little space, various vegetable crops like brinjal, cauliflower, onion, cabbage, methi, etc. can also be cultivated as intercrops in the radish field. Sometimes, it is grown as an intercrop in orchards and as border crop in onion, wheat, and chili fields.
Harvesting of radish:
Roots are harvested immediately after the roots achieving edible and marketable size. Early maturing spring varieties will become pithy if they are not harvested after getting maturity. Summer and winter types will remain edible for prolonged times if stored well. In radish, maturity varies from about 3 – 4 weeks for the fast-growing spring varieties and 8-14 weeks for Chinese types. At these stages, radishes are tender, mild, and crisp, usually of the proper marketable size. Radishes grown for the home garden and with small plantings are pulled by hand and tied up in bunches of 6-12 in the field and washed to remove dirt and soil. Tops of winter radish are removed before they kept for storage. Harvesting was done with the help of mechanical harvesters in commercially grown crops in the United States.
Topping just below the growing tip will improve the keeping quality of radishes. Radish roots are packed in plastic bags after topping. They are cooled quickly to 5°C or below to maintain the crispness of roots. Hydro cooling is said to be the best method of cooling radishes. Radish roots can be stores well up to 3 – 4 weeks at 0°C.