Temperate Vegetables (1+1)

SEED PRODUCTION

For seed production, the radish varieties can be divided broadly in two groups.

A. Temperate Varieties/ European types:

• Which produce satisfactory seed in the temperate hills by over wintering.
• These varieties flower very late in plains.
• Seeds of such varieties are produced in hills only.
• Those temperate varieties viz. White Icicle, Rapid Red White Tipped, Pusa Himani, Scarlet Long and Scarlet Globe, which are very quick in root development in plains, but behave just like winter varieties both from winter and spring sowing.
• Autumn sown crop gives higher seed yield and mature earlier.

B. Tropical Varieties/ Asian types :

• Which produce seeds freely in plains. (e.g Pusa Reshmi, Pusa Chetki, Japanese White, Chinese Pink).
• The seeds of these varieties are usually produced in plains, but good quality seed of some of these varieties i.e. Japanese White can also be produced in hills.

Methods of Seed Production

• Root to seed method
• Seed to seed method

Time of Sowing

• For seed production purpose, adjust sowing time in such a way that roots must get ready by the onset of winters for receiving chilling stimulus particularly in European types.
• For hills: Autumn sowing preferably may be done in early October.
• Spring sowing can also be done in March, as soon as land is prepared.
• However autumn sowing gives higher seed yield.

Preparation of Field

• Prepare the field to fine tilth by 2-3 ploughings and 3-4harrowing followed by levelling.

Spacing

• 45 cm X 45 cm

Nutrient Management

• In addition to root crop, apply 200-250q/ha of well rotten Farm Yard Manure at the time of preparation of land.
• At the time of final levelling, also apply 35kg nitrogen, 50kg, phosphorous and 50kg potassium per ha as basal application.
• Another dose of 35 kg /ha nitrogen is top dressed, when the roots just start growing.

Irrigation

• Irrigate the crop at 8-10 days interval depending upon weather conditions conditions
• During early warm weather it is advisable to irrigate the crop at 4-5days interval.

Interculture

• One weeding and earthing up during the early stages of growth are necessary for proper emergence of seed stalk.

Selection of Roots

• Uproot the plant when they have attained maturity (30-70days) depending upon the variety.
• After harvesting, each root is critically examined for foliage and root characteristics namely, size, shape, colour, texture, sponginess etc.
• Roots having off type foliage or roots not conforming to varietal characteristic must be rejected.
• The diseased, malformed, forked or any other undesirable types are also rejected.

Preparation of stecklings from selected roots

• After selection, the top is cut off in such a way as to leave small underdeveloped leaves together with about 2cm of petioles of older leaves.
• It is usual practice to cut 1/3^rd of lower root portion in Asiatic types but whole roots are used in European varieties.
• These are reset/replanted in well prepared fields at a spacing of 60x45cm in Asiatic and 45x45cm in European types.

Flowering and fruit setting

• Honey bees are chief pollinating agents.
• It has been demonstrated that seed yield in radish is greatly influenced by number of honeybees visiting the flowers.
• Nectar secretion, pollen formation and bee activity was influenced by environment.
• It has been proved that radishes grown for seed production should not be located too close to field of major honey producing plants such as clover because the bee tends to visit these plants in preference to radish.
• It is a cross pollinated crop due to the presence of self incompatability especially sporophytic self-incomtability.
• A temperature of 32^oC or higher causes stigma to become dry and pollen fail to germinate.
• A period of dry weather might cause formation of underdeveloped Pods.
• Combination of cold storage and GA₃ spray (100ppm) after replanting leads to highest percentage of flowering in White Icicle, Pusa-Himani and Japanese White.

Isolation requirements

• Radish is cross pollinated by insects, chiefly honeybees.
• Seed field should not be located too close to cover crops.
• Seed field must be away from field of other radish varieties, fields of same varieties not confirming to varietal purity requirement for certification.
• At least 1600 meters for foundation seed production and 1000 meter for certified seed production should be kept.

Roguing

• Plants with off-type foliage and the direct bolters are eliminated from the field prior to flowering and crop is left to seed.
• When roots are lifted, they are critically examined for true to type, besides small sized, over sized stecklings, diseased, forked and off types should be discarded.
• Normally 3 roguings are done, mainly before maturity of roots for off types foliage, at time for replanting for verifying root characteristic such as size, shape, colour, texture etc. and last at flowering stage for early and late plants affected by designated diseases like black leg and black rot and eliminate them).

Harvesting and threshing

• The crop is cut when plants are fully matured.
• Crop is cut with sickle and brought to threshing floor for threshing.
• There is more often difficulty in threshing the seeds from pods.
• The pod does not break easily to allow the seed to escape.
• It is therefore, important to thoroughly dry them before commencing the threshing.
• Radish pod do not dehisce even after maturity.
• Threshing can be done by beating with the sticks.
• Seeds afterwards should be dried to 6 per cent moisture before storage.

Seed Yield

• Asiatic types : 9-12q/ha,
• European types : 4-5q/ha

• 1000 seed weight is about 10g.

SEED CERTIFICATION STANDARDS
1. Field Inspection

A. Mother root production stage

• Minimum of two inspections should be made as follows:
• Inspection should be done after 20-30 days of sowing in order to determine isolation, volunteer plants, out crosses, off types and other relevant factors.
• Second inspection is done after mother roots have been lifted to verify true characteristic of roots.

B. Seed production stage

• A minimum of one inspection is done during flowering to check isolation, off type and other relevant factors.

2. Field Standards
a. General Requirements

Isolation

Contaminants	Minimum distance (Meters)
	Mother root production stage		Seed production stage
	Foundation	Certified	Foundation	Certified
Fields of other varieties of same species	5	5	1600	1000
Field of same variety not conforming to varietal purity requirements for certification and for rat tail radish (Raphanus caudatus)	5	5	1600	1000

b. Specific Requirements

Factors	Minimum Permitted (%) limits
	Foundation	Certified
*Roots not conforming to the varietal Characteristics including for seed roots	0.10	0.20
**Off Types (Plants)	0.10	0.20
Plants infected by seed borne diseases	0.10	0.50

• Max permitted at second inspection at mother root production stage.
• **Max permitted after flowering and at seed production stage.

• Seed borne disease to be considered shall be Black rot and Black leg

 

3. Seed Standards

Factors	Standards for each class
	Foundation	Certified
Pure seed (minimum) %	98.0	98.0
Inert matter (maximum ) %	2.0	2.0
Other crop seed (maximum) Numbers/kg	5	10
Total weed seeds (maximum) Numbers/kg	10	20
Germination (minimum) %	70	70
Moisture (maximum) %	6.0	6.0
For vapour proof containers (maximum) %	5.0	5.0