Seed Production
Climatic requirements
- Cabbage thrives well in a cool, moist climate with moderate rainfall.
- It can withstand frost in the head stage.
- It requires a dormant period of cool temperature (Chilling/vernalization) to bolt and initiate seed stalks and flower.
- After the cold treatment at 4 to 7oC for 4-6weeks, the plant bolt sooner and flower more abundantly but the plants must have passed juvenile phase (pencil thickness of stem).
- Intensity of flowering depends upon age of plants and 3-5months old plants are capable of transformation (early vernalized) since they pass the juvenile phase.
Land requirements:
Land should be free from volunteer plants and crop debris.
Methods of seed production
- Being a biennial, cabbage requires two seasons to produce seed.
- For seed production, sowing time should be adjusted in such a way that heads get ready by the onset of winters.
- In the first season, the heads are produced and in the following season formation of seed stalks begin and the process of seed production follows.
- The seed crop can be left in situ or replanted during autumn.
- The in-situ method is usually followed for certified seed production and the ex-situ for nucleus seed production.
- In in-situ method, the crop is allowed to over winter and produce seed in their original position, i.e. where they are first planted in the seedling stage.
- In higher hills where heavy snowfall is experienced during winters, heads are uprooted and stored in trenches to avoid snow injury to the heads.
- In replanting method, the mature heads/plants are uprooted.
- After removing whorls (non wrapper leaves), the plants are immediately reset in a well prepared new field, in such a way that the whole stem below the head is set in the soil with the head resting just above their surface.
Ex-situ/replanting method of producing seed of cabbage:
This method is further divided into three methods to produce seed of cabbage:
i) Stump method:
- In this method, when the crop in the first season is fully mature, the heads are examined for true to type.
- The plants with off type heads are removed.
- Then heads are cut just below the base by means of a sharp knife, keeping the stem with outer whorl of leave intact.
- The beheaded portion of the plant is called ‘Stump’.
- The heads are marketed and the stumps either are left in-situ, or replanted in the second season i.e. during autumn.
- The following spring, after the dormancy is broken, the bud sprout forms the axils of all the leaves and leaf scars.
Advantages:
- This method gives extra income by way of sale of heads.
- The crop matures 12-15days earlier than the head intact method and seed yield is slightly higher.
Disadvantages:
- In this method, flowering shoots are decumbent and require very heavy staking, otherwise they breakdown very easily while interculturing or spraying.
ii) Stump with central core method:
- In this method, when the crop is fully mature in the first season, the heads are examined for true to type.
- Plants with off-type heads are removed and rejected.
- Then the heads are chopped on all sides with downward perpendicular cuts in such a way that the central core is not damaged.
- This is an improvement over stump method in that the shoots arising from the main stem are not decumbent.
- During the last week of March, and until 15th April, when the heads start bursting, two vertical cross-cuts are given on the heads (Kalpa valley of HP).
- Taking care that the central growing point is not injured.
- In the absence of such cuts, the heads burst out irregularly and sometimes the growing tip is broken.
- The operation is completed by going around the field twice or thrice during this period.
Advantages:
- Shoots arising from the main stem are not decumbent, hence very heavy staking is not required and seed yield is increased.
Disadvantage:
- The chopped head can not be marketed.
iii) Head intact method:
- In this method, when the crop is fully mature in the first season, the heads are examined for true to type.
- The plants with off-type heads are removed from the field.
- The head is kept intact and only a cross cut is given to facilitate the emergence of a stalk.
Advantage:
- The removal of head (stump method) or chopping of heads on all sides (central core intact method) is not required.
- This saves time and labour and staking is not required.
Disadvantage:
- The seed yield is slightly low as compared to stump and stump with central core intact method.
Brief Cultural Practices(In-situ method)
Time of sowing and transplanting
- The sowing time of different varieties should be adjusted according to complete head formation by the end of October or first week of November in high hills before snowfall.
- When the mean temperature falls to 10oC or below the heads stand best for over wintering.
- Early varieties are sown from 10th July to 25th July and transplanted when the seedlings are three to four weeks old.
- The late crop, planted during September does not form heads and bolts directly during spring.
- Late varieties takes about 2 to 3 months to produce mature heads and should be sown during the second and first fortnight of June, respectively and transplanting finished by the first week of August.
- The mean temperatures viz., 22.5oC, 20oC and 14oC of August, September and October, respectively, afford optimum requirements for growth and head development.
- The transplanted crop starts head formation during spring and continues up to June and usually does not produce seed stalks.
Preparation of land for replanting
- Prepare the land to a fine tilth by repeated ploughings and harrowings followed by leveling.
Nutrient management
- Cabbage grows well only when the supply of organic matter is liberal.
- In addition to head crop, apply 100quintals of farmyard manure per hectare at the time of land preparation for good seed crop.
- Also apply about 100 kg nitrogen, 100 kg phosphorus and55 kg potash per hectare before replanting of heads.
- Another dose of 50 kg/ha nitrogen will be applied at the time of seed stalk emergence during March –April.
- Extra application of nitrogen may be given as and when there is a need before flowering starts, depending upon the condition of the crop.
Spacing
Irrigation
- Cabbage requires a continuous supply of moisture.
- Irrigate the crop as frequently as required.
- Heavy irrigation should, however, be avoided when the heads are formed.
- A sudden heavy irrigation after a dry spell may cause bursting of heads.
Hoeing and Weeding
- At least three weddings and hoeing till the end of October are essential.
- One weeding and earthing up during June the second during August is required which control weeds and also help in proper drainage during winter and thereafter.
Handling the Mature Head
- Before the onset of winters, fully developed heads are uprooted and selected on the basis of varietal characteristics for seed production.
- Handling of plants can be done by any one of the methods described earlier.
Roguing
- The first roguing is done at the time of uprooting and selection of the mature heads.
- All off type heads, diseased, or otherwise undesirable types, are removed at this stage.
- The second rouging is done before the heads start bursting.
- The loose leaved, poorly heading plants and those having a long stem with heavy frame must be rouged out at this stage.
- It is highly undesirable to keep such poor plants in the seed plots.
- Subsequent roguing for off-types, diseased plants affected by phyllody, black leg, soft rot or leaf spot should be done from time to time as required.
Staking
- After the flower stalks are sufficiently developed, staking is necessary to keep the plants in an upright position.
Harvesting and Threshing
- Cabbage starts seed stalk elongation from March onwards when the mean temperature rises to 10-13oC.
- Flowering and pod formation starts during the first week of April at mean temperature of 13-18.5 oC.
- From 15th April, to 15th May, the crop is in full flush of flowering and fruiting.
- The ripening of pods commences by 15th June to 20th June and the harvesting continues up to second week of July.
- At mean temperature below 20oC during June and July, the maturity of crop is delayed at least by a fortnight and the harvesting may continue up to July end.
- To avoid shattering of seeds, the whole crop is harvested in two or three lots with sickles.
- Generally, the early maturing plants are harvested first and when the pod colour is about 60-70per cent of the rest of the crop changes to yellowish brown, it is harvested completely and piled up for curing.
- After 4-5days, it is then threshed with sticks and sifted with hand sifters.
- Afterwards, the seeds are cleaned and stored.
Seed Yield
SEED CERTIFICATION STANDARDS
I. Field inspection
- A minimum of three inspections should be done, the first before the marketable stage, the second at the marketable stage and the third at flowering stage.
II. Field standards
A. General requirements
Isolation:
- Seed fields should be isolated from the contaminants shown below:
|
Contaminants
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Minimum distance (Meters)
|
|
|
Foundation
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Certified
|
|
Fields of other varieties
|
1600
|
1000
|
|
Fields of the same variety not conforming to varietal purity
|
1600
|
1000
|
B. Specific requirements
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Factors
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Maximum Permitted (Per cent)
|
|
|
Foundation
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Certified
|
|
Off types
|
0.10
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0.20
|
|
Plants affected by seed borne diseases
|
0.10
|
0.50
|
C. Seed Standards
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Factors
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Standards for each class
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|
Foundation
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Certified
|
|
Pure seed (minimum) %
|
98
|
98
|
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Inert matter (maximum) %
|
2
|
2
|
|
Other crop seeds (maximum) Number/kg
|
5
|
10
|
|
Weed seeds (maximum) Number/kg
|
5
|
10
|
|
Germination (minimum) %
|
65
|
65
|
|
Moisture (maximum) %
|
7
|
7
|
|
Participants