Method of seed production

Method of seed production

    Stages of seed production
    • Breeder seed → Foundation seed →Certified seed
    • Bellary Red, Rampur local, Pusa white, Kalyanpur, Red Round, Punja 48, Pusa red, Pusa Madhvi, Arka Niketan, Arka Kalyani
    • The optimum sowing season is middle of June to Middle of July in the plains.
    Isolation Requirements
    • Onion is largely cross-pollinated crop with up to 93 per cent natural crossing but some self-pollination does occur.
    • It is chiefly pollinated by honey-bees.
    • For pure seed production, the seed fields must be isolated from fields of other varieties of onion and fields of the same variety not conforming to varietal purity requirements for certification atleast by 1000 meters for foundation seed production and 500 meters for certified seed production.
    Method of Seed Production
    There are two methods of seed production

    1. Seed to seed method
      In this method, the first season bulb crop is left to over-winter in the field so as to produce seed in the following season.
    2. Bulb to seed method
    • The bulbs produced in the previous season are lifted, selected, stored and replanted to produce seed in the second year.
    • Mostly the bulb to seed method is used for seed production because of the following advantages over the seed to seed method.
    a) It permits selections of "true-to-type" and healthy bulbs for seed production.
    b) Seed yields are comparatively very high. The seed to seed method, however, can be practiced for varieties having a poor keeping quality.
    2. Bulbs to Seed Method
    Production and storage of bulbs (first year)
    Sowing time (nursery)
    • Middle of October to middle of November in the plains and April to June in the hills. 1/20 hectare nursery is sufficient for raising seedlings for one hectare.
    Seed rate
    • Eight to ten kg per hectare.
    Seed treatment
    • Soaking of bellary onion (cv. Rampur Local) seeds with 100 ppm GA3 for 3 hrs increased the germination (from 50 to 90 per cent) and vigour.
    • Add 20 tonnes of well-rotted farmyard manure at the time of land preparation and 250 kg super phosphate (single) and 45 kg potassium sulphate at the time of planting. 250 to 375 kg of ammonium sulphate or CAN may be applied as top-dressing in two to three doses during the growing period.
    • Eight to ten weeks old seedlings are planted in small beds in well-prepared fields.
    • Spacing depends upon variety and bulb size and varies from 10 to 15 cm.
    • Fortnightly irrigation during winter weekly irrigation during hot weather. Irrigate sparly during maturity.
    • Keep field free from weeds. Frequent inter culture is essential for good bulb development. For controlling weeds, post-emergence application of tenoran at 2 kg per hectare in 800 liters of water, two to three weeks after transplanting is recommended. Oxadiazon one kg active ingredient per hectare has also given for effective control of weeds.
    Insect and disease control
    Onion thrips

    • Spray malathion 50 EC at 600 to 700 ml per hectare or thiodan 35 EC at 600 to 700 ml per hectare. Three to four applications may be required. Onion maggot can be controlled by spraying with sevimol.

    • Use treated seed. In cases of seedlings mortality, drench nursery with 0.3 per cent captan or thiram or dithane Z-78 at weekly intervals.
    Purple blotch
    • Spray with copper fungicides such as blitox 50 at 0.2 per cent.
    Plant protection - Pests
    Thrips and onion fly
    • Methyl demeton 25 EC 1 ml/lit or dimethoate 30 EC 1 ml/lit or monocrotophos 36 WSC 1 ml/lit with Teepol 0.5 ml/lit.
    • Drench the soil with chlorpyriphos @ 2 ml/lit.
    Leaf spot
    • Spray Mancozeb 2 gm/lit or Copper oxychloride 2.5 gm/lit. Add Teepol 0.5 ml/lit ofspray fluid.
    Harvesting and curing of bulbs
    • Well-matured bulbs should be harvested. Maturity is indicated by the tops drooping just above the bulb, while the leaves are still green. After harvesting, the bulbs should be topped leaving a half inch neck. Before storage, a thorough selection and curing of bulbs should be done. The length of time required for curing depends largely on weather conditions and may take three to four weeks.

    • The essentials of successful storage are
    a) The bulbs should be well-matured, dried and cured before storage.
    b) Storage should be well-ventilated.
    c) Storage should be done in shallow trays with perforated bottoms.
    d) Storage temperatures should range 0 to 4.5° C until three to four weeks prior to planting, when the temperature should be increased to around 10° C.
    Planting of bulbs and seed production (second year)
    Time of planting bulbs
    • The best time for planting bulbs is the second fortnight of October.
    Preparation of land
    • Prepare the field to good tilth. One deep ploughing, followed by three to four harrowings and land levelling are enough.
    Seed rate
    • The seed yield is affected by the size of the bulb. The bigger the bulb size, the higher is the seed yield. However, very large sized bulbs, if used, will need very high seed rate. If bulb size of 2.5 to 3.0 cm diameter, is used for planting, approximately 15 quintals of bulbs per hectare are required.
    • Same as described for first year.
    Method of planting and spacing
    • Selected bulbs are planted 8 to 10 cm deep in the soil at a distance of 45 x30 cm. The size of beds depends upon the source of irrigation. The sprouted bulbs are planted as such. In unsprouted bulbs, the upper half portion should be removed, leaving the disc-like stem and roots intact. The removal of the upper tops hastens sprouting.
    Foliar application
    • Foliar application of GA3 (100 ppm) or IAA (100 ppm) increase the seed setting per centage.
    Insect and disease control
    • Same as described for first year.
    First year
    • It is desirable to begin roguing in the field before bulbs are harvested, since it is then possible to detect any plants having a different foliage colour or plant type or late maturing bulbs. After harvesting, the bulbs should be carefully rogued for colour and such off-types as thick-necks, doubles, bottlenecks, as well as any other types which do not conform to varietal type.
    Second year
    • plant only selected true-to type bulbs and remove plants not conforming to varietal characters before flowering.
    Specific field standard

    Field standard
    Other variety bulbs (max.) 0.2%
    Off types (max.) 0.2%

    Harvesting and processing
    • The maturity of seed ready for harvest is indicated when (April-May).
    • On full maturity, the seeds turn into black colour.
    • The matured seed bunches are harvested before shattering and dried .under shade.
    • Normally two to three harvest are required depends up on the maturity of the seed.
    • Harvest the seeds at intervals by cutting the seed head with 10 15 cm of stem attached.
    • The harvested umbels are heaped for a few days for drying before threshing.
    • This helps in proper curing of seed then the seeds are separated from the capsules by hand threshing or using pliable sticks.
    • The seeds are cleaned, graded by using 10 x 10 BSS sieve, dried to 6 8 % moisture content and treated with Bavistin / Thiram @ 2 3 g/kg of seed.
    Seed Yield
    • The average seed yield varies from 850 to 1000 kg per hectare.
    Seed standards: (Variety & Hybrid)
    Factors Foundation Certified
    Pure seed (min) 98% 98%
    Inert matter (max) 2% 2%
    Other crop seeds (max) no/kg 5/kg 10/kg
    Weed seeds (max) no/kg 5/kg 10/kg
    Germination (min) 70% 70%
    Moisture (max) 8% 8%
    For VP container (max) 6% 6%

Last modified: Monday, 25 June 2012, 4:53 AM