Seed production of Onion, Pea & Hyacinth Bean
Seed production is very specific branch of vegetable gardening. Different factors must be considered during seed production of vegetable crops. They are: –
- The plot of same vegetable crops should be kept sufficiently apart so that natural crossing can be avoided. So, isolation distance of 300-600 m is maintained for cross-pollinated & 100-200 m in self -pollinated crops.
- The site for seed bed should be clean land which is not only weed free but also free from major soil borne diseases & pests.
- Adequate roguing is important for seed production. Rogues are removed at earlier possible date flowering. At least three rouging is necessary.
- About 60% of vegetable crops are cross-pollinated or insect pollinated. For insect pollinated crops, provision of honey bees in hives in close proximity will ensure greatly increased seed yield. Bumble bee & other insects are useful as pollinators.
- Application of insecticides, dusts & spray should be done early in the morning or evening when bees are inactive to avoid bee injury.
For the seed production of onion, isolation distance of 1000 m is kept between two varieties. Keeping two bee hives/ha gives good seed yield. Two methods are employed in the production of onion seeds.
- Bulb to seed method:
- Seed to seed method:
Bulb to seed method:
This is most commonly used method. This involves first producing bulbs as for the market and replanting them for seed production. Bulbs of first season are harvested during summer and are stored carefully till October at optimum temperature of 12 degree Celsius. Before storing roots are not cut, roguing of bulbs is practiced before and after the harvest. Only true to the type and disease-free bulbs are selected for replanting. The growing portion of the bulb is cut to the extent of 1/4th for easy and quick sprouting. Bulbs are planted in the month of October and seeds are harvested after 4-5 months of bulb planting. Thus, this method takes 2 seasons (about one & half two years) for seed production.
Bulbs having 2.5 – 3 cm diameter is ideal for planting. The cut bulbs are dipped on Bavistin solution @ 20 gram/10 liter of water to prevent rotting in the field. About 1500 kg bulbs / ha are planted on both edges of 45 cm wide ridge at 30 cm distance. The aftercare and irrigation for seed crop are the same as those for onion raised for bulbs.
Since, the ripening of seed is not uniform, it is desirable to cut the seed head (umbel) when 10% seed head have explored black seeds. The heads are dries in well ventilated shady place and then threshed. The seeds are then dried (3-6% moisture) in the sun for a week or two before they are stored. The seed yield from this method is about 850 – 1000 kg / ha.
Advantages of Bulb to seed method:
- For nucleus and foundation seed production, bulb to seed method is to be followed because storing and replanting of bulbs provides an opportunity for selection, roguing & field inspection.
- There is lower seed yield.
- In some varieties which have lower keeping quality of bulb such as M-53, Pusa red this method is not suitable.
- Take two seasons (one and half two years) to produce seeds.
- It involves higher cost of production.
Seed to seed method:
There are some varieties which do not store well or sometime wants the seed within the same year, in such cases the seed are sown in August and seedlings are transplanted in September. Most of the bulbs give out flowering stalks and forms seeds in the month of December to January. This method has higher seed yield comparing to bulb to seed production method.
Seed production of Pea:
Pea is a self-pollinated crop. Hence two cultivars can be grown in adjacent plots without and danger of out crossing. So, an isolation distance of 20 m is recommended for foundation seeds. Pea cop produces off-type plants which multiply radially if not rogued out every year. Hence, roguing of off-type plants at flowering and fruiting stage is necessary. The ripe fruits when they are handpicked and threshed easily. Average seed yield of pea is 20 – 25 quintals / ha.
Seed production of Hyacinth bean:
It is a self-pollinated and partially cross-pollinated by insects. Different cultivars should be grown 50 m apart in case of foundation seeds and 25 m apart in case of certified seeds. For seed production, it should be grown as a pure crop staking with vines. Ripe matured pods can be handpicked from the standing crops. Threshing can be done by beating pods with stick or under the feet of bullocks. Seeds should be thoroughly cleaned and dried before bagging. Average yield of hyacinth bean is 6-8 quintals / ha.