Cauliflower is cross pollinated crop &the pollination is mainly done by bees. Some bee hives when kept in the seed production plots increase seed set. Proper isolation distance (1600 m) is essential between two varieties for the production of seeds. The early season varieties are produced in the Terai. The seeds of main season varieties are produced in the hills.
There are different seed production techniques for different cultivars. The seed production method for early cauliflower mainly includes two different methods:
- In-situ method:
- Transplanting method:
Brief description of these methods are as below:
The usual method is to leave the plants with good curds in the field where they flower and produce seeds. A very thorough roughing of off type & undesirable plants is essential before flowering for quality seed production. The seed ripens during April-May. This is best method for rasing seeds since:
-It is easy & most economical method of seed production.
-This method yields relatively better quantity (500-650 kg/ha) & quality of seeds.
-Seeds are obtained 4-11 days earlier than from other methods.
In-situ method occupies a lot of area in the field for seed production as plants for seed production are here & there in the field. It is recommended that selected plants with best curds may be uprooted carefully with ball of earth & re-planted at spacing of 75 cm * 75 cm in a solid block for seed production. It is necessary that the field is well prepared & manured before transplanting. The curd of plant before transplanting or at the time of transplanting is given scooping in the middle of the curd. Scooping helps in the early emergence of the flower stalks.
Since the crop is harvested at 70% pod maturity, curing becomes essential. curing threshing & other operation should be completed before the onset of rain.
Similarly, in seed production method for main season cauliflower, in-situ method is the most successful method. Cauliflower should be sown at such time that the vegetative growth is completed by 15th of December. For this, seed must be sown in nursery by the last week of August & transplanting is completed by the end of September. If the temperature falls below freezing point before vegetative growth, the plants remain small & when temperature rises again, very small curds are formed thus giving a very low yield of seeds. If transplanting is done early, curds may be formed before freezing temperature and may be damaged. Scooping of curd is beneficial. Seed yield varies from 250-400 kg/ha.
Cabbage is biennial in nature for seed production. During first year, heads are formed 7 next year seeds are produced. It requires chilling temperature of 4.4-10 degree Celsius for 30-60 days for seed production. Cabbage seeds cannot be produced in plains. It is produced by two methods:
- Seed to seed method : For higher quantity of seed produced in small area of land.
- Head to seed method : For higher quality of seed production in small area of land whereas quantity is very less in this method.
Lets learn in detail about these methods !
Seed to seed (In-situ method):
For this purpose, cabbage is transplanted in last week of September & seeds are ready by May-June next year. Plants with good head are left in field where they flower & produce seeds. Rouging of off type plants in beginning & head formation stage. It is of 3 types:
- Head intact method:
It is most common method of commercial seed production of cabbage. Heat is kept intact & only a cross cut is given on the head to facilitate the emergence of flower stalk in the month of March when head start bursting or bulging or give dome shape appearance.
- Stump method (without central core):
Heads are cut just below the base by a sharp knife, keeping stem with outer leaves intact. The de-headed portion is called stump. In following season when temperature starts to rise, the bud’s sprouts from the axils of the leaves & leaf scars. Seed yield is more but the flower stalk requires stalking otherwise they may break down easily during inter-cultural operations.
- Stump with central core intact:
Heads are chopped on all sided but not removed ensuring central core is not damaged. During the last week of February & till march when the heads start bursting, two vertical cross cuts are given to the head taking care that the central core is not damaged. The flowering shoots arises from the terminal & auxiliary buds.
Head to seed method:
Selected heads of cabbage are uprooted with ball of earth on November-December & replanted in a compact block at 75 cm * 75 cm spacing for seed production. They are re-planted in such a way that the whole stem below the head goes underground with the head resting just above the surface of soil. After re-planting, two cuts of 2-5 cm deep are given at right angles across each head so that the seed stalks may develop normally.
The average seed yield is 500-700 kg/ha.