Wednesday, February 21Food Security Matters

Radish Farming: How to Plant and Grow Labanos

Radish farming in the Philippines is one of the major income sources of many Filipino farmers and in this article, we are going to discuss radish farming, or how to plant and grow labanos.

Radish (Raphanus sativus), is one of the major vegetable crops in the Philippines. It is highly appreciated by consumers for its pungent taste. It could be eaten raw in salads, prepared as pickles, or cooked with fish, meat shrimp, and other meals.

Due to its popularity, radish is often planted in many home gardens or raised commercially in the field. Out of 52,630 hectares devoted to vegetable growing in the country, 2,050 hectares were planted to radish with a normal average production of 11,269 metric tons (BAS,1979).

There is a vast area for the production of radish as a vegetable, but ironically, there is no local seed production effort to satisfy radish seed requirements resulting in complete dependence on foreign seed sources. One main reason for this is the lack of technical information on local seed production of the crop and its feasibility. It is in this line that this paper is written as a guide for potential seed growers, extension workers, researchers, students, and others interested in local seed production of radish. This guide is based on seed production trials in farmers’ fields and experiment stations located in low, medium, and high elevations.


Radish Farming: Soil and Climatic Requirement

Radish produces a good yield of seed under temperate climates with less humidity, especially during the reproductive stage. High temperature during flowering causes drying of stigma and non-germination of pollen resulting in a poor seed yield.

In the Philippines, it is best grown for seed production at higher elevations of 2000 feet or above, to fulfill low-temperature requirements.

The vast area of high elevation (e.g. Benguet, Mt. Province, mountainside of Mt. Banahaw, Mt. Makiling, Mt. Kanlaon, etc.) offers a great opportunity for radish seed production in the country.

For seed production, fertile sandy loam and silty loam soil with slightly acidic conditions (pH 6-6.8) is recommended. The soil should be deep, friable, rich in organic matter, and relatively free from disease-causing micro-organisms.

Recommended Variety

The most popular radish variety grown in the country is the ‘60-days’ variety. It possesses an excellent eating quality, high potential yield, good handling, and storage quality. Its roots are long and large with white skin and attain maximum marketable size within 60 days from emergence. This variety is often pollinated and is ideal for local seed production. With proper vernalization technique, it could be made to flower in about 75 days, mature in about 120 days, and produce good seed yield.

Radish Farming Culture and Management

A. Time of Planting

Planting time must be initially planned for the best result. The flowering of the crop should coincide with the coolest month of the region to fully fulfill the cool climate requirement. Likewise, pod maturity and harvesting must be during the dry season to minimize seed losses due to lodging brought about by heavy rains and obtain favorable conditions for harvesting and other post-harvest operations.

B. Vernalization Requirement

To induce early, abundant, and uniform flowering, radish requires vernalization. Vernalization of radish first requires incubation of the seeds to allow the radical to come out of the seed coat. This is done by soaking the seeds in an equal amount of water for 24 hours. After incubation, the seeds are laid in trays lined with moist paper or cheesecloth two centimeters thick and placed in a cold room under 50 Ctemperaturefor eight days. The seeds should always be maintained in a moist condition during vernalization.

C. Land Preparation

Preparing the land for planting varieties with the soil and field conditions in the selected site. Shallow and depleted soils require pre-planting conditioning to obtain good texture and structure. This involves deep plowing and incorporation of an adequate amount of inorganic matter such as well-decomposed animal manure. Likewise, fields with dense weeds must first be cleaned thoroughly before initial land preparation. Soils should be plowed and harrowed alternately at least twice to attain favorable texture and structure. Raised beds one meter wide and 30 centimeters high are prepared following the slope of the area to ensure good drainage and ease of other field operations. A day before planting, a shallow canal of five centimeters deep and 30 centimeters apart is made on top of the bed.

D. Planting

Planting the vernalized seeds in the field can be done any time of the day as long as there is adequate moisture in the soil. In planting, three to four germinated seeds are carefully placed in the shallow furrow 20 centimeters apart. The seeds are immediately covered with a thin layer of soil about one centimeter thick by gently passing a rake on top of the bed. The vernalized seeds should always be maintained in moist conditions during planting to prevent drying. Irrigation should follow days after planting to ensure good emergence and seedling stand.

E. Fertilization

The amount of nutrients to be applied depends on the initial soil fertility level and soil organic matter content. An initial assessment of the nutrient level of the soil through soil analysis will help determine the amount of fertilizer to be applied. In general, however, radish seed production requires a rate of 120-90-90 kilograms per hectare of Nitrogen; Phosphorus, and Potassium ( N; P2O5; and K2O ). All of the P and K and half of N are best applied in the soil during land preparation. The fertilizer should be incorporated properly and thoroughly to prevent contact with the vernalized seed for it may cause injury to the seedlings. The remaining half of N is side-dressed three weeks after emergence. The field should be thoroughly weeded and crops properly thinned before side-dressing.

F. Irrigation

Water should be applied more frequently during the early part of the growing period. Adequate irrigation should be done immediately after planting. Likewise, the application of water once a week until the seedling had fully established should be continued. Other stages where water is initially needed are during the vegetative, flower initiation, and pod development stages. Irrigation water can be applied either by overhead sprinkler method or by furrow irrigation.

G. Thinning

The purpose of thinning in radish seed production is two-fold; to maintain the proper density of the crop and to rouge off-types and diseased plants. The crop is thinned to about one to two plants per hill at the early part of its seedling stage to minimize overcrowding. Likewise, off-types and diseased plants are rouged to obtain seeds that are pure and disease-free.

H. Weeding and Cultivation

The most applicable method of weeding in radishes is by cultivating the space between the rows and hills. Cultivation must be thorough enough to control weeds but must also be shallow (eight to 10 centimeters deep) to avoid serious root injury. Weeding must start on the earliest date when weeds are observed. In this way, weed control will be easier.

I. Insect Management

The annotated listing and suggested control for common radish seed production pests are given in this section. Suggested guide for chemical control of radish pest is prevented.

Harvesting and Other Post Harvest Operations

a. Harvesting

Radish pods do not shatter even if allowed to fully ripen in the fields. However, when the pods are mature enough, the crop should be harvested as soon as possible to minimize the risk of seed loss due to birds or unexpected heavy rains. The crop is ready for harvest once the pods turn matured and brownish and are brittle enough for cracking. The seeds must be brownish in color, firm, and hard. In harvesting, the flower stalks where the pods cling are cut and gathered. Then they are allowed to dry in an open area.

b. Threshing

To have easy threshing, the pods are first separated from the stalk by hand or by passing and pulling the stalks in a comb-like stripper. The separated pods are collected and sun-dried to become more brittle and pounded using a wooden mortar and pestle to break the shell of the pods. The seeds are then separated from the shell of the pod by passing them in a sieve or by winnowing.

c. Drying

Seeds should be dried properly to about 7o/o content before packaging to prolong their storage life. To attain such moisture content two days of continuous sun-drying will be enough. When the climatic condition does not permit sun drying, overnight drying in a conventional type grain (palay and corn) drier will be sufficient to attain the target moisture content.

d. Seed Testing

The seed must be tested for its germinability and purity. Seed samples must be analyzed to determine whether they are of good quality. Seed quality can be determined by National Seed Quality Control Services ( NSQCS) seed laboratories located in the different regions of the country, where the seed sample of the crop produced could be given for analysis.

e. Packaging

Packaging seed materials must be air-tight and moisture-proof. For commercial qualities, seeds could be packed in plastic bags and must be sealed using a plastic sealer. Certain information such as the name of the crop, place of harvest, date of harvest, percent germination, etc should be labeled on the package

If you want to know more about the cost and return analysis of radish farming, you may download the radish production guide PDF from the DA website here.

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