Foundation and Certified Seed Production in Onion
Notified Varieties of Onion:
N-2-4-1, N-53, B-780, AFLR,AFDR.
It is biennial crop and takes two full seasons for producing seeds. Bulbs are formed during first year. While flower and fruiting take place during second- year. It requires cool climate during early development of bulbs and also during early growth of the head stalk ( Flowering). Blotting takes place between 10 to 15 0C. During early stage, temperature should be cool with good moisture supply. Seed production is undertaken in temperate and subtropical region.
Select the field for onion seed production in which the onion crop was not taken in the preveious year. Soil should be rich in organic matter with good water holding capacity.
It is highly cross pollinated crop with 93 % cross pollination brought by honey bees. Field should be isolated by 1000 meters. For foundation and 400 meters for certified seed production plot from other fields.
iv) Methods of Seed Production:
There are two methods as below
a) Seed-to Seed. In this method first season bulb crop is kept in the fields up to winter so as to produce seed in the next season.
b) Bulb-to –Seed method. Bulbs produced in the preveious season are selected , stored and replanted in next year for production of seed . It is most common method.
The seeds from approved source is produced and sown at the rate of 8 to 10 kg/ha in the nursery for raising seedlings. Sowing is done in the month of October or November. Seedlings of 8 to 10 weeks old are ready for transplanting. Such seedlings are transplanted in small beds 10-15 cms apart.
Well matured bulbs should be harvested when tops are druped and leaves are still green. After harvesting , bulbs should be thoroughly selected for curing. The time required for curing. The time required for curing depends on weather condition i.e 3 to 4 weeks.
Well matured , dried and cured bulbs are taken for storage. Such bulbs are stored in well ventilated storage. The shallow trays with performed bottoms are used. The temperature range should 0 to 5 0 C for 3 to 4 weeks prior to planting and may be increased upto 10 0C thereafter.
Seed Production ( Bulb-to Seed) :
The bulbs of proper size (2.5 to 3.0 cm dia) are selected for planting. About 15 quinatal of bulb are required for one hectare and planting is done in second fortnight of October. The selected bulbs are planted at a distance of 45 to 30 cms with 8 to 10 cm depth. The sprouted bulbs are directly used for planting while upper portion of unsprouted bulbs is cut and disc like portion is used for planting.
Off types plants having different foliage colour, late maturing bulbs etc are removed during first year and at the time of harvest also, bulbs having different colour, neck thickness and doubleness are rejected. During second year, the plants differing and not conforming to varietal characters are removed.
First formed seeds in the head get blacked harvesting is done. Two to three picking are necessary to harvest the heads at right stage, heads are cut by keeping small stalks and after proper drying, threshing is done with sticks. Seeds are cleaned by dipping in water for 5 to 10 minutes followed by sun drying.
The average yield of 850 to 1000 kg/ha is obtained from good crop.