Method of seed production

Method of seed production

    Method of seed production
    1. Seed to seed method for varieties which do not stand transplanting (In situ method)
    2. Root to seed method (Transplanting method)
    Stages of seed production
    • Breeder seed → Foundation seed → Certified seed
    Varieties:
    • Co- 1
    Temperate varieties (Chinese type)
    • Produce seed in the hills by over wintering. These varieties flower very late in the plains
    Temperate varieties
    • White icicle, Rapid red, Woods, Long frame, French break fast, these produce seed in the plains also, but behave just like winter varieties for seed production in plains.
    Tropical varieties:
    • Pusa Reshmi, Pusa Chetki, Japanese white, these produce seed freely in the plains.
    Season
    • For hills September October and Plains April June.
    Seed production systems
    • Both "root to seed" & "seed to seed" systems are used. The 'root to seed' is used for the biennial types especially in Europe and temperate regions. The roots are lifted in the late autumn, the tops taken off and the radishes are stored, usually in clamps, during the winter. It is also the method used for stock seed production of the annual types but in this case the material is replanted immediately after selection. In some areas of the world, especially in Asia, up to half of each steckling's root is removed before replanting. In seed production of the Japanese White cultivar steckling planting results in a higher seed yield.
    • The 'seed to seed' system is used for final multiplication stages where inspections of the mature root are not considered necessary and is normally used only spring sown seed crops unless the cultivars has a vernalisation requirement.
    Roguing stages (seed to seed method)
    1. At market maturity stage of radish, root: relative size, shape, coloured, proportions of each colour on bi coloured cultivars, solidity.
    2. At stem elongation, removed early bolting plants and off types according to stem colour. Remove wild radish types. Check that the remaining plants are true to type for foliage and stem characters.
    3. At flower bud and very early at start of anthesis flower colour. Plants with off colour flowers are rogued.
    Land requirement
    • Select seed fields on which the same kind of crop was not grown within previous two years, unless the crop with in the previous two years were field inspected by the certification agency and found not to contain any seed borne diseases beyond the maximum permissible levels.
    Isolation requirement
    • Radish is cross pollinated crop by insects. Hence, seed fields must be isolated from other varieties of radish field at least by 1600 m for foundation and 1000 m for certified seed production.
    Seed rate
    • 4 to 6 kg per hectare. The roots are produced in one hectare is sufficient for transplanting in 2.5 hectares.
    Sowing
    • It is advisable to sow the seeds on ridges formed at 45 cm apart, in lines as thin sowing. This helps in better root development and drainage. When the seedlings are 10 to 15 days old, thin out the seedlings to a distance of 7 to 8 cm with in the rows.
    Manuring
    First season
    • A light does of 20 25 tons of FYM per ha should be applied before field preparation.
    • Nitrogen 75 kg/ha (35 kg basal + 35 kg top dressing)
    • Phosphorus 50 kg/ha (basal)
    • Potash 50 kg/ha (basal)
    Second season (During transplanting)
    • Farm yard manure 10 to 15 tons /ha
    • Nitrogen 50 kg (25 kg at pre bolting + 25 kg before flowering)
    • Phosphorus 50 kg (basal)
    Supplementary pollination
    • Since the honey bees are important pollinating agents. It is advisable to place beehives in the large seed fields or near by the field to increase the pollination. It is necessary when the temperature is below 15°C.
    • Spraying of 150 ppm NAA at bolting stage in Japanese white radish recorded the highest seed yield per hectare (Sharma, 1995).
    Roguing
    • Minimum of three field inspections should be done at 20 30 days after sowing, when roots are lifted and replanted and during flowering stages.
    • Roguing should be done based on root character, flower character and the undesirable and diseased plants are to be removed.
    Field standards
    Factor Maximum permitted (%)
    Foundation Certified
    Off types (maximum) 0.10 0.50
    Plants affected by seed borne disease 0.10 0.50
    Roots not confirming to varietal characteristics 0.10 0.20

    Pest and disease management
    • At the time of flowering, indiscriminate use of insecticides may result in lowering the bee population, pollination and seed set. Use of insecticides during flowering affects the insect pollinators and will result in poor seed set.
    • A single soil application of granulated Phorate 10G, Dimethoate @ 18 Kg/ha during early February for control of sucking pests (Aphids) is advisable.
    • In radish the major disease is "Damping off".
    • Thin sowing and drenching with 150 g of Bavistin in 100 liters of water will control the disease.
    • White rust disease can be controlled by spraying of Mancozeb 2 g/lit or copper oxychloride 2 g/lit.
    Harvesting and processing
    • The entire plants are cut when the plants are fully matured and the siliqua turns brown colour.
    • Thorough drying of siliqua is must for easy separation of seeds.
    • The seeds are separated by beating with pliable sticks.
    • The seeds should be dried to 6% moisture content, cleaned and treated with Bavistin @ 2g per kg of seed.
    Designated diseases
    • Black rot (Xanthomonas campestris pv. Campestris)
    • Black leg (Leptbsphaeria maculans)
    Seed standards
    Factor Foundation Certified
    Pure seed (minimum) 98% 98%
    Inert matter (maximum) 2% 2%
    Other crop seed (maximum) (no./kg) 5/kg 10/kg
    Total weed seed (maximum) (no./kg) 10/kg 10/kg
    Germination (minimum) 70% 70%
    Moisture (maximum) (normal container) 6% 6%
    For VP Container(maximum) 5% 5%

Last modified: Monday, 25 June 2012, 6:37 AM