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Seed production on Cole crops
Cole crops are temperate vegetables also known as European vegetables requiring temperate climate especially during a specific stage of their growth for successful seed production. During this period that these vegetables must have the vernalization requirement a pre condition necessary for breaking the dormancy of the plant thus stimulating the conversion of the vegetative phase into the reproductive phase i.e., induction of bolting and flowering.
All Cole crops are hardy and thrive best under condition of cool climate. They are grown in the plain during winter season and can be cultivated throughout the year in the hill regions of the country.
Origin:
All crops of this group have originated from single progenitor wild cliff cabbage known as Cole worts (Brassica oleraceae var sylvistris.) as a result of mutation. All the Cole crops belong to the same genus brassica and most of them to the same species.
Cole crops are Mediterranean in origin and are spread all over European and have been cultivated continuously since 2500 BC. Curly Kale, Cabbage, Knol kohl were the first known cultivated types and other were cultivated in later centuries.
Cauliflower became widely known in 18th century and Brussels sprouts in the 19th century. In the 30’s of the 20th century, another form ‘Sprouting Broccoli’ in USA. Now Cole crops are grown in every corner of the world.
Different types of Cole crops
Sl. Crops Botanical Name Chromosome number (n) Plant parts used
1. Cabbage Brassica oleraceae (L) var. capitata 9 Heads
2. Cauliflower Brassica oleraceae (L) var. botrytis.L. 9 Curd
3. Knol Kohl Brassica oleraceae (L) var. gongylodes. L. 9 Swollen stem
4. Brussels sprouts Brassica oleraceae (L) var. gemnifera 9 Sprouts (Swollen axillary buds)
5. Sprouting broccoli Brassica oleraceae (L) var. italica 9 Flower heads
6. Kale Brassica oleraceae (L) var. acephala 9 Top leaves
Constraints for seed production:
- Problems of satisfactory isolation due to cross-pollination by insects.
- Crops have to be carried over in to the second season
- Plant attains morphological shape and size during the additional growing period, which is not known to majority of the seed growers.
Major seed production areas in the world.
1. North western Europe: Eastern and South Eastern, UK, Holland, Western Denmark
2. Central Europe: Southern Sweden, Eastern Denmark, North Germany, Switzerland
3. Mediterranean area: Southern France, Southern Italy
4. North America and Canada: Western USA (Pacific North West), Canada (British Columbia)
5. California.
Seed production areas in India:
1. Srinagar valley (J&K)
2. Upper Kullu valley (Himachal Pradesh)
3. Lahaus valley (Himachal Pradesh)
4. Kalpa valley, Kinnaur (Himachal Pradesh)
5. Saproon valley, Solan (Himachal Pradesh)
6. Kumaon hills (Uttar Pradesh)
7. Kalimpong – Darjeeling hills (West Bengal)
8. Nilgiris (South India)
In 1942-43 for the first time imperial Government encouraged the seed production of European type of vegetable at Quetta in Baluchistan. At about the same time initial trials on seed production were also initiated in Kashmir, Katrain (Kullu valley) (Verma and Sharma, 1999)
Inflorescence:
After leafy growth ceases, as for example the completed growth of the head of the cabbage, or the sprouts of Brussels sprouts, the flowering stem elongates. It is characterized by numerous branches (mostly from a main stem), small leaves, and numerous bright yellow or occasionally white flowers. The flowers of all Cruciferae have four petals, l/2 to 1 inch long, that appear to form a cross, hence the name Cruciferae (cross bearing).
The flowers are typical of crucifers’ family having 4 petals, 6 stamens, of which 2 are short and 2 carpels with superior ovary. The flowers are attached with the stalk with a short pedicel. The anthesis of flowers depends on temperature and flowers open mainly during hotter part of the day. The flower opens during the morning, the anthers a few hours later, so the flower is slightly protogynous. The flowers are highly attractive to pollinating insects for both nectar and pollen. When the seed-producing acreage is large, beekeepers nearby frequently harvest a crop of excellent honey. The stigma of Brsassica spp. is receptive even 5 days before and 4 days after anthesis. The period from pollination to fertilization generally takes 24-28 hours, depending on temperature. Higher temperature during daytime is more harm full for fertilization and this causes pollen sterility. The pod maturity or harvest of pods may require 50-90 days from the date of flowering. The seeds are small, globular, smooth and dark brown in colour. The Cole crops are highly cross-pollinated the percentage of cross-pollination varies with the type of crops. The Cole crops are highly cross-pollinated as characterized by both self-incompatibility and protogyny. The self-incompatibility is of sporophytic type, and it is using for the hybrid seed production program, self-pollination of Brassica resulted in decreased yields in subsequent generations.
Percent of cross pollination in Cole crops.
Crop Cross percentage
Cabbage 73%
Cauliflower 70%
Knol kohl 91%
Sprouting broccoli 95%
Brussels sprouts 72%
Kale 83%
Flowering season and Vernalization temperature
Sl.No. Crop Flowering season Vernalization
1. Cabbage March - May 4.4-100C
2. Cauliflower February- April 10-160C
3. Knol kohl March - May 4-100C
4. Sprouting broccoli February- April 10-150C
5. Brussels sprouts April-May 2.2-100C
6. Kale March- April 4-80C
The blossom forms a siliqua, incorrectly but commonly called a pod.
Vernalization
Vernalization of Brassica oleraceae is performed on mature vegetative plants, which are uprooted in autumn from the fields, potted and over wintered in a greenhouse at temperatures between 5-10°C. The cabbages are decapitated (±3 cm of head remains). Other Brassicas are defoliated, leaving ±6 leaves, to prevent rotting. Early cabbages are decapitated in the field, and the new growing shoots are cut and rooted. The cuttings are placed in a cooling compartment for 1 day, to desiccate the cutting surface. No leaves are removed, to avoid the creation of fresh tissue wounds. The cuttings are planted in trays with soil and covered with cheesecloth. After roots are formed, the cuttings are potted. The plants from these rooted cuttings over winter.
Isolation
In brassica there are two distinct groups which do not intercross with each other, Brassica oleraceae with all its botanical varieties and wild allies in one group and B. rape, B.junceae, B, chinensis, etc., from another group.
CAULIFLOWER
India is the largest producer of Cauliflower in the world (FAO, 2001). With the development of tropical types in Cauliflower in addition to the temperate type, it has now become possible to grow this vegetable almost throughout the year particularly in the northern and central part of India. Cauliflower is thought to have been domesticated in the Mediterranean region since the greatest range of variability in type of brassica oleraceae. It became more commonly cultivated in the beginning of the 18th century. Indian or tropical cauliflower, which are early maturity and wider adaptability to hot and humid weather conditions. Temperate types are known as ‘Snow ball’ or late cauliflower. Cauliflower is a monogenic species whose genomic constitute is C and n=9.
Varieties are very specific to the season when the curds are formed; they are two major groups of cauliflower;
1. Early or Indian cauliflower: are annual types
2. Late or Snow ball types: biennial types. They require low temperature for transition to generative phase i.e., curd initiation stage. Their behavior to curding is like cabbage for transition to reproductive stage.
Early group is further divided into three maturity groups on the basis of period of their curd availability. I, II, III require high temperature for growth and curd formation where as late group produces curds at low temperature.
Climate:
Requires cool, moist climate for seed production. The optimum monthly average temperature is 15 to 20 C. the early varieties, however, require high temperature and longer day lengths. It is less tolerant to extreme high or low temperatures, or strong winds. It is also susceptible to cold injury after the curds have appeared. Excessive rains and snowfall, after curd formation, cause rotting in curds. Periods of low temperature are not essential, but cool conditions are required. Therefore, these conditions must be given due consideration in selecting suitable areas for seed production. In India, the seed production of early and mid-season varieties can be done in the plains. However, the seed of late varieties can only be produced in temperate regions of the country. Lately, Himachal Pradesh has emerged as the major producer of quality cauliflower seed of late varieties.
Land Requirements:
- Land to be used for seed production shall be free of volunteer plants.
- The soil of selected field should be deep, fertile, well-supplied with organic matter with a pH value 5.5
- The field should be well drained.
Isolation Requirements:
Cauliflower is mainly cross-pollinated. Pollination is mainly done by bees. The seed fields must be separated from fields of other varieties, fields of the same variety not conforming to varietal purity requirements of certification, and from all their kinds of Cole crops, at least by 1600 meters for foundation seed class, and by 1000 meters for certified seed class.
Method of Varietal Seed Production:
1. In situ method (seed to seed method)
2. Transplanting method (head to seed method)
For seed production, seed to seed method is recommended since the head to seed method in India has not been very successful. In seed to seed method (in situ method) the crop is allowed to over-winter and produce seed in the original position, where they are first planted in the seedlings stage. Main season and late varieties (seed production in hills)
Time of sowing and transplanting:
In the hills, the sowing time of cauliflower should be so adjusted that the plants put up the maximum leafy growth by the fifteenth of December, when the temperature goes down and the plants become almost dormant. The last week of August is the optimum sowing time for the crop. The seed is sown in a nursery. Transplanting of seedlings should be completed by the end of September. The mean temperature of 6.5 to 11 C during February to March is very conducive to curd formation, which is completed by the first fortnight of March.
Early sowing in June to July result in curd formation during October to November. The curds, being very susceptible to cold injury, rot during winter and hence fail to flower the following summer. If sown late, the crop starts curd formation late in the spring and consequently flowering is delayed. It starts when the temperature is high and humidity is low, with the results that pollination and setting of seed is not normal.
Method of sowing in nursery:
Seeds may be sown on raised nursery beds (15 to 20 cm high from the ground), in rows 5 cm apart. Cover the seeds with fine leaf mould and water with a sprinkler. Twenty-five nursery beds of 2 to 2.5 meters long and 1 to 1.25 meters wide will raise enough seedlings to plant one hectare. A spray of four to five handfuls of ammonium sulphate or C.A.N. dissolved in 30 to 35 liters of water at 10 to 15 days after germination will be helpful in producing healthy and vigorous seedlings. Wash out the fertilizer immediately by spraying simple water. Thin sowing should be done to avoid “damping-off” disease.
Source of seed: Obtain breeder’s /foundation seed from source approved by a seed certification agency.
Seed rate: Mid season and late varieties – 375 to 400 g /ha.
Preparation of land for transplanting: The field should be prepared to fine tilth by deep ploughing, three to four harrowing followed by leveling.
Fertilization:
The cauliflower seed crop required heavy manuring as it removes large quantities of major nutrients from the soil. For best results apply 50 to 60 tones of farmyard manure at the time of land preparation. Normally 25 to 30 tones of farmyard manure is applied per hectare due to limited availability of farmyard manure in hills. Apply 200 to 300 kg superphosphate and 100 kg potassium sulphate sufficiently before sulphate, or calcium ammonium nitrate, during growing period (one application during October to November, another in February to March is essential). Still higher doses of nitrogen may be applied it deemed necessary. Cultural practices determine greatly the seed yield and among the various inputs, nitrogen and phosphorus application have been reported to exert a great influence on the seed yield of Cauliflower.
A cauliflower crop often shows boron and molybdenum deficiency symptoms when grown either on an alkaline or highly acidic soil, or two sprays with 0.3 per cent borax applied on the seedlings may correct the boron deficiency. Molybdenum deficiency symptoms occur in highly acidic soils and can be corrected by liming, or application of about 1 to 1.5 kg per hectare of sodium molybdate. Spraying of 150 ppm Ethrel at the time of emergence of flowering stalks increase seed yield.
Transplanting:
Transplant the seedlings when 12 to 15 cm long, preferably at evening time, and irrigate immediately afterwards.
Spacing:
Row to row 60 to 90 cm and
Plant to plant 45 to 60 cm.
Irrigation:
Irrigate the field according to the soil requirements and climatic conditions. A crop after transplanting may need irrigation twice a week and later once a week. At later stages, irrigation may be given if there is a long gap between rains. Adequate moisture supply during flowering and seed maturation are necessary to obtain high yields.
Intercultural:
Frequent shallow cultivation should be given to the soil to kill weeds and provide soil mulch. Earthing-up of plants four to five weeks after transplanting is highly desirable.
The seed production is dependent upon curd formation and its bolting. Bolting further depends on the curd type i.e., degree of compactness of the curd. The loose curd bolts easily while compact curds takes more time to bolt. To facilitate bolting, different curd- cutting methods like scooping, half curd cutting and curd pruning are recommended. These practices have impact on branching, seed yield and seed quality.
Scooping (Single Scoop): Approximately half of the curd was removed from the center with the help of a sharp knife.
Curd pruning: The outermost curdlets were pruned 5cms, away from the center.
Half- curd removal: The curd was cut vertically into two parts from the middle and one of them was removed leaving half portion of the curd intact for seed production.
Roguing:
Selection of curds is done when the curds are well developed. Off-type plants, and those forming poor curds, should be removed at this stage. Subsequent roguings for off-types, and diseased plants affected by blackleg, black rot, leaf spot and phyllody should be done from time to time as required.
The developmental process in Cauliflower is regulated by temperature. Low temperature stimulates curd induction at the end of a juvenile phase and further development of the curd, stalk, flower and seed proceed sequentially at rates determined by prevailing temperatures. Seed production in Cauliflower is difficult because of its seasonality, which restrict field production both in the tropics and temperate regions. In tropics, seeds are produced in the cool season or at high altitude where temperatures are relatively low.
Harvesting and Threshing:
Harvesting is done when pods brown. Too ripe pods dehisce. Seed should not crush or split when rubbed between the hands. The harvesting maybe done in two lots. Generally the early plants are harvested first, when about 60 to 70 percent of the pods turns brown and the rest of the crop changes to yellowish-brown. After harvesting it is piled up for curing. After four to five days it is turned upside down and allowed to cure for another four to five days in the same way. It is then threshed with sticks and sifted with hand sifters. After thorough drying of seed in the sun (seven percent moisture content) it is cleaned and stored.
Seed Yield: Average seed yield varies from 250 to 400 kg per hectare
CABBAGE
Cabbage is one of the important vegetables grown on a large scale in India, which is formed by the development of densely overlapped leaves around the growing point. Cauliflower is mostly grown in North India whereas cabbage is popular in the south and South Eastern parts on India. Cabbage has been under cultivation since 2500 BC to 2000 BC. It is a biennial in nature having 2 specific periods of growth namely vegetative and reproductive phases to complete its life cycle. In the first season crop remains in the vegetative phase characterized by the formation of heads where as the reproductive phase is completed in the second season only after getting the necessary stimuli of low temperature of 4.40C-100C for about 60 days to break the dormancy of the heads. Cabbage is commonly used fresh as salad, Cole slaw, boiled vegetable cooked in curries and processed.
Floral biology of cabbage:
Cabbage flowers are borne in terminal raceme, flowers are yellow in colour. They are hypogynous having slender pedicels. The flowers are perfect, regular with 4 sepals, 4 petals, 6 stamens, ovary two celled with several ovules per cell. Cabbage starts flowering in the month of February- march or earlier. The stigma remains receptive for about 5 days before and 4 days after anthesis. Cabbage fruits is siliqua, having a thin partition dividing it lengthwise, along with it dehisce when fully mature and dry. Pod contains about 12-20 seeds.
Cultivated forms of cabbage:
White cabbage : Brassica oleraceae Var. Capitata L.Falba
Red cabbage : Brassica oleraceae Var. Capitata L.frubra
Savoy cabbage : Brassica oleraceae Var. sabauda L.
Based on maturity time.
Earlyseason: it takes 60-70 days for maturity.
Golden acre, Pride of India, Copenhagen market and Early drumhead.
Mid- season: cabbage comes to harvest at 80-90 days.
All head early, Wisconsin, All green september.
Late season: Require long winter season comes to harvest at 90-120 days
Pusa drum head, Indian eclipse, Danish ball head, Late flat and Dutch sure head.
Based on shape of heads.
Round head or Ball Head type (early): Golden Acre, Pride of India, Copenhagen Market, Mimmothi, Rock red and express.
Flat head or Drumhead type (Late): Pusa drumhead.
Conical head (early to mid season): Jersy wake field
Savoy type (late varieties): Chieftain
Climate:
Cabbage thrives in a relatively cool, moist climate with moderate to heavy rainfall, well distributed during the growing season. It can withstand frost in the head stage, but otherwise freezing temperatures are destructive. It requires a dormant period of cool temperature to bolt and initiate seed stalks and flowers. Cool temperatures, however, are effective only after stem diameter is one cm, at least. In temperate climates, this occurs during the winter after the first seasons growth. Flowering and seed production follow in the second year. Headed plants form seed stalks when exposed to mean temperature of about 5C for six to eight weeks. As little as two weeks of such temperature suffice with immature plants. In India, seed production of cabbage is possible only in hill areas.
Methods of Seed Production:
Being a biennial, the cabbage requires two seasons to produce seed. In the first season the heads are produce, and in the following season seed production follows. The seed crop can be left in situ or transplanted during autumn. In situ method is usually followed for certified seed production and the latter for nucleus production.
In the in situ method, the crop is allowed to over-winter and produce seed in their original position, that is, where they are first planted in the seedling stage. In the transplanting method, the mature plants are uprooted. After removing whorls the plants are immediately reset in a well-prepared new field, in such a way that the whole stem below the head goes underground with the head resting just above the surface.
Three methods have been devised to produce seed of cabbage.
Stump Method:
In this method, when the crop in the first season is fully mature, the heads are examined for trueness 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 leaves 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 buds sprout from the axils of all the leaves and leaf scars.
Advantages
1.Gives extra income by way of sale of heads.
2.The crop matures twelve to fifteen days earlier than the head intact method.
3.Seed yield is slightly increased.
Disadvantages:
In this method, flowering shoots are decumbent and require very heavy staking, otherwise they breakdown very easily while inter culturing or spraying.
Stump with Central Core Intact Method
In this method, when the crop is fully mature in the first season. The heads are examined for trueness to type. Plants with off-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 February and until 15th March when the heads start bursting, two vertical cross-cuts are given to the head, 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:
1.Shoots arising from the main stem are not decumbent, hence very heavy staking is not required.
2.Seed yield is increased.
Disadvantages:
1.The chopped heads cannot be marketed.
Head Intact Method:
In this method, when the crop is fully mature in the first season the heads are examined for trueness 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.
Advantages:
1.The removal of heads (stump method) or chopping of heads on all sides (central core intact method) is not required. This saves time and labour.
2.Very heavy staking is not required.
Disadvantages;
1.The seed yield is slightly low as compared to stump, or stump with central core intact method.
Cultural Practices:
Time of Sowing and transplanting:
The sowing time of different varieties should be so adjusted as to complete head formation by the end of October or first week of November, by which time the mean temperature falls to 100C or below; at this temperature the heads stand best for over-wintering.
Early varieties like ‘Golden Acre’ should be sown from 10th to 25th July and transplanted when the seedlings are three to four weeks old, during the second fortnight of August. This sowing time must be strictly adhered to, as the crop from the early sowings have matured heads during September and starts pre winter bursting and bolting. It is thus liable to be much affected by frost and snow during winter. Moreover, due to high mean temperatures of September (20 0C) the heads get infected with bacterial stock rot, which sometimes is very severe. The late crop, planted during September does not form heads and bolts directly during spring, and the seed grower is not able to ascertain purity of the crop.
Medium-late varieties like burpee’s Sure Head, and late varieties like Drum Head, which take about 2 1/3 to 3 months to produce mature heads, should be sown during the second and first fortnight of June respectively, and transplanting finished by the first week of August. The mean temperatures 22.5C, 20C and 14C of August, September and October respectively, afford optimum requirements for growth and head formation. The late transplanted crop starts head formation during spring and continues up to June and usually does not produce seed stalks (Singh., 1959).
Method of sowing nursery:
The seeds are sown in raised nursery beds in a manner similar to that of cauliflower.
Source of seed and seed rate: Obtain breeder’s/foundation seed from source approved by a seed certification agency. Mid season and late varieties – 375 to 400 gm per hectare and early varieties 600-750 gm per hectare.
Preparation of land for transplanting: Prepare the land to a fine tilth by repeated ploughing and harrowing, followed by leveling.
Fertilization:
Cabbage grows satisfactorily only when the supply of organic nitrogen is liberal. For best results apply 50 to 60 tones of farmyard manure per hectare, at the time of land preparation. Since the supply of farmyard manure is very limited in the hills, only 25 to 30 tones farmyard manure per hectare, is usually applied. Apply 200 to 300 kg superphosphate and 90 kg of muriate of potash by drilling. Top-dress two doses of 75 to 100 kg ammonium sulphate at intervals of two to three weeks after transplanting the seedling. Give another dose of 200 to 250 kg ammonium sulphate as surface application at the time of seed stalk emergence during March.
Transplanting: Three to four weeks old seedlings are transplanted. Transplanting should preferably be done in the evening and the field irrigated immediately afterwards.
Spacing:
Late varieties - 60 x 60 cm
Medium varieties - 60 x 45 cm
Early varieties - 45 x 45 cm
Irrigation: Cabbage requires a continuous supply of moisture. Irrigate the crop as frequently as required. Heavy irrigation should, however, be avoided when the heads have formed. A sudden heavy irrigation after a dry spell may cause bursting of heads
Hoeing and weeding:
At least three weedings and hoeings till the end of October are essential. One weeding and earthing up during November and December and the second during March, when seed stalks have emerged, control weeds and also help in proper drainage during winter and thereafter.
Roguing:
- The first rouging is done at the time of handling the mature heads.
- The Second roguing is done before the heads start bursting. The loose-leaved poorly heading plants, and those having a long stem and heavy frame, must be rogued out at this state. It is highly undesirable to keep such poor plants in the seed plots.
Harvesting and Threshing:
Cabbage starts seed stalk elongation from 10-20th March when the mean temperature rises to 10-13 C. Flowering and pod formation starts during the first week of April at mean temperature of 13-18.5C. 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 temperatures below 20C 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 plants are harvested first and when the pod colour in about 60-70 per cent of the rest of the crop changes to yellowish-brown it is harvested completely and piled up for curing. After 4-5 days, it is turned upside down and allowed to cure for another 4-5 days, in the same way. It is then threshed with sticks and sifted with hand sifters. After thoroughly drying the seeds they are cleaned and stored.
Seed yield: 500 to 650 kg per hectare
Knol-Khol
Knol khol was first described in 18th century as another cabbage of western Europe. Knol-khol is characterized by formation of turnip like knobs, which is used for human consumption before it becomes tough and fibrous. This knobs arises from the thickening of the stem tissues above the cotyledons.
Time of Sowing and transplanting:
The seed is sown in the nursery from seventh to fifteenth August the seedlings are planted in the field during the first fortnight of September and the operation may continue up to the end of the third week the crops planted during October and later, fail to form good knobs.
Preparation of Land:
For transplanting Prepare the field well by ploughing and three to four harrowings before the seedlings are set in the field.
Seed Rate:
Main season and late varieties – 375 to 400 gm per hectare and early varieties 600-750 gm per hectare
Sowing of Seeds in Nursery:
The seeds are sown in raised nursery beds in a manner similar to that of cauliflower.
Fertilization:
Apply 20- 25 tones of farmyard manure per hectare at the time of preparation of field apply 100 to 150 kg superphosphate per hectare at the time of land preparation. Top-dress 100-150kg ammonium sulphate per hectare after first weeing. Top-dress another dose of 100-150 kg ammonium sulphate per hectare during spring when the crop recommences growth after over wintering. Extra application of nitrogen may be done before flowering, if necessary.
Transplanting:
Three to four week old seedlings are transplanted. Transplanting should preferably be done in the evening and the field irrigated immediately afterwards.
Spacing:
Row to row - 60 cm
Plant to Plant - 45 cm
Intercultural:
One hoeing and weeding during September to October, and one weeding and earthing-up during November to December is required. Keep the crop clean till the spring when one more hoeing and earthing -up is done (Verma and Sharma, 1999)
Roguing:
- Selection of Knobs is done during February to March when the knobs are well developed only true-to-type plants are retained. Off-types, or diseased plants, are removed.
- Subsequent roguing is done at the flowering stage. The off-type plants observed at the flowering stage, are usually determined by the extent of branching of the flowering shoots. the higher the production of fully branched plants, the greater is the seed yield. Therefore, care is necessary in nucleus seed production to select the right type of plants at flowering stage. Remove any undesirable plants.
- Subsequent roguing for off-types, diseased plants affected by diseases such as phyllody, black-leg, black rot, soft rot or leaf spot should be done from time to time as required.
Harvesting and Threshing:
Seed stalk elongation starts from 10-20th March when the mean temperature rises to 10-13 C. Flowering and pod formation starts during the first week of April at mean temperature of 13-18.5C. 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 temperatures below 20C 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 plants are harvested first and when the pod colour in about 60-70 per cent of the rest of the crop changes to yellowish-brown it is harvested completely and piled up for curing. After 4-5 days, it is turned upside down and allowed to cure for another 4-5 days, in the same way. It is then threshed with sticks and sifted with hand sifters. After thoroughly drying the seeds they are cleaned and stored.
Seed Yield: The average seed yield is about 500 to 600 Kg per hectare.
BRUSSELS SPROUTS
Brussels sprouts is a popular vegetables in European countries which gained importance in the nineteenth century. The sprouts are the edible part of the plant, which are used, in different preparation. The sprouts are the buds in the axils of the leaves, which developed into miniature cabbage like heads. In India Brussels sprouts as not been common among the people. Like all other cole crops, it has been originated in the Mediterranean region from wild cabbage. It is a temperate vegetable requiring vernalization for transformation to the generative phase. Being biennial in nature, its seed production is possible in temperate regions, which are normally suitable for cabbage and knol-khol seed rising.
Floral biology:
Transition from vegetative to reproductive occurs only when it is exposed to low temperature of 2.22 – 100C for 42-56 days. The juvenile phase is complete in about 90 days. The flowers stalk arise from the terminal growing point and also from sum of the upper sprouts. The flowering takes place from the April to May. The flowers are typical of crucifers family having 4 petals 6 stamens and superior ovary. The anthesis of flowers depends on temperature and open mainly during hotter part of the day. Honeybees are the usual pollinating agents.
Cultivars:
Dwarf cultivars:
Improved Long Island, Early Morn, Dwarf Improved, Frontier Zwerg and Kvik.
Tall cultivars:
Eveshan rapid, Wilhelmsburg, Hilds ideal, Red vein, Amager and De Rosny Polarstjernen
Climate:
Brussels sprouts does well in cool and humid climate. This can be grown in regions with moderately severe winters. Although yields are higher in regions with cool mild summer and mild winters.
Plants at this stage of 30 leaves, the apex increases in size and becomes globular in shape due to the formation of sessile leaves and becomes globular in shape due to the accumulation of nutrients. At this stage the plant is sexually mature to receive the vernalization stimulus. On exposure to low temperature at this stage, the flower primordial will develop. As soon as temperature starts rising in spring, these plants bolt and produce flowers. Day length does not have any effect on this process. The sprouts become loose at higher temperature in autumn.
Soil:
The soil should be moisture retentive and well supplied with organic matter. Waterlogged soil should not be used for seed crop, which results in poor and stunted growth of the crop.
Fertilization:
Brussels sprouts need heavy intake of nutrients for the formation of firm sprouts of good quality, an even growth ism important. The recommended fertilize dosage is 200:80:100 kg NPK/ha. Nitrogen is applied in 4 equal split doses, first at the field preparation along with P and K, second 30 days after transplanting and the third at initiation of sprouts and the last at the time of bolting.
Spacing:
Varieties with large leaves and larger sprouts are spaced widely at a spacing of
90 x 90 cm, whereas those with smaller leaves and smaller sprouts required a spacing of 60 x 60 cm or 60 x 45 cm. About 500-600 g of seed is sufficient to produce seedlings for 1 ha.
Sowing And Transplanting:
The optimum time for sowing in the hills is second week of July and transplanting should be done by the end of August for seed crop.
Strong winds during flowering and seed maturity stage do greast damage due to lodging because of the more height of the plant. The staking of plants is needed under such conditions.
Roguing:
1. Vegetative / pre marketable stage
2. Full grown stage
3. Bolting and pre-flowering stage
Seed yield: 300-400 kg/ha.
Sprouting Broccoli
Sprouting broccoli is less important in India and is grown by some people in the kitchen garden. It has been originated in Italy, as the name broccoli as been derived from Italian world ‘brocco’ refers to development of young shoots, which have been used as vegetables. Inspite of morphological resemblance with cauliflower and heading broccoli, the sprouting broccoli differs from these in plant habit and in producing green heads consisting of green buds and thick, fleshy flower stalks.
Floral biology
The central growing point along with the axillary buds clusters form thick, fleshy flower stem, which is the actual consuming parts in broccoli. The length of the flower stem is small and the flower primordia develops into normal buds, which are united into a cluster, commonly called as head. Heads of broccoli becomes loose quickly and the buds start opening. The process of flowering starts at low temperature but pollination and seed setting will not occur until the average daily temperature goes above 150C. Flowering starts from down upwards in all the branches, first at the main axis. The flowering is even and the whole crop flowers simultaneously. Between 20-300 C day temperature, flowering, pollination and seed setting go on satisfactorily. Higher temperatures result in pollen sterility and low seed setting.
Climate:
It is not much sensitive to hot weather. A period of comparatively low temperature is not as essential for the production of sprouting broccoli seeds as it is for cabbage. Above mean temperature of 200C, the flower buds open prematurely and the bud cluster become loose quickly, and results in undesirable leafiness in the heads. Sprouting broccoli is hardy and exhibits resistance to fairly heavy frosts depending on the variety and the developmental stages of the plant.
The annual varieties are more sensitive to frost in the vegetative stage than the biennial ones. But, in the bud production stage even a light spell of frost does a considerable damage resulting freezing, browning and ultimately rotting of bud clusters.
There are two types of seed production:
1. Annuals: are early whose seed can be produced in tropical / subtropical
2. Biennials: late in maturity although require same climatic conditions as are required by other Cole crops.
The period from sowing to flowering is shorter, so, they are sown slightly later than Cauliflower. Growing biennial type for seed is easier as they can withstand frost better in vegetative stage and over winter in the field. The annual types are not hardy and are susceptible to frost hence, the seed production is not possible in hills.
Method of seed production is exactly same as in Cauliflower since the transplanting method is not successful because there is no rest period between the sprouts/curd stage and flowering in broccoli and cauliflower. The transplanted allow to grow, over winter, flower and produce the seed at the same place i.e., in-situ method.
Manures and fertilizers:
10-15 tons FYM/ha
200:100:100 NPK kg/ha.
Nitrogen is applied in four splits, one is along with the P and K as basal dose, second after 25-30 days after transplanting, third 30 days after second application and last application before flowering.
Spacing:
Annual or Early varieties: 45 x 45 cm
Biennial or Late varieties: 60 x 45 cm
45 x 45 cm
Seed rate:
Annual or early varieties: 600-750 g/ha
Biennial or late varieties: 500-600 g/ha
Time of sowing should be adjusted in such a way that he heads are formed only after the danger of frost or snowfall is over. As the period from sowing to heads formation is shorter than cauliflower, sprouting broccoli should be sown or transplanted slightly later. Sowing of seed is done in third weak of October so that plants are well established to withstand frost or snowfall during winter. Being shallow rooted like other Cole crops, it needs shallow cultivation to check the weeds at the initial stage.
It can also produce seeds in the plains of Northern India, as seeding characters is similar to mid-season group of cauliflower. Since, it requires same temperature range for growth, head formation, flowering and seed setting and is not much sensitive to hot climate. Flowering period is shorter than Cabbage but equivalent to cauliflower. The adverse climatic conditions affect, flowering, pollination, fertilization and seed setting.
Rouging:
1. Marketable stage
2. Marketable size
3. Bolting and pre flowering stage
Harvesting:
Generally the seed ripen in June, when 70% of the pods have turned brown and the rest of the crops change to yellow brown. Harvesting should be done preferably in morning hours to avoid shattering.
Seed yield: 500-600 kg/ha
KALES
Kales is of not much importance in India except grown by amateur kitchen gardeners. Like other Cole crops this has originated from wild Cabbage through mutation. There are different sub varieties, which bear a resette of leaves at the top of the stem.
1. Subvar. Laciniata: curly kales having finely curled foliage.
2. Subvar. Plana: smooth leafed kales
3. Subvar.millecapitata: thousand head kales with sprouted axillary buds forming loose leafy rosette
4. Subvar. Palmifolia; tree kales having more plant height up to 2 m.
5. Subvar. Medullosa; tree kales marrow stem kales with long swollen stem.
It is the curly kale that is grown for human consumption and is one of the earliest forms of Cole crops cultivated by the Greeks as early as 600BC. The top leafy rosette or individual leaves are harvested for vegetables. The other types of kales are used as fodder for livestock. For vegetable purpose kales should be grown at temperature around 18-200C as there is likelihood of the plants going to flower early. The flowers of kales are white and they retain their edibility even at the bolting stage.
Climate
For seed production kales behave as biennial in that it requires low temperature for vernalization. Kale is hardiest of Cole crops. Adult plants of hardy varieties can tolerate temperature from –100C to –150C. Freezing improves the quality of the leaves and even making edible the older leaves which have stringy midrib.
Seed production
The seeds of kales can be produced in a manner similar to Brussels sprout. The crop continues making rosette of leaves at the top of stem till late winters. If the rise of temperature they start bolting and thus there is no dormant stage while transition in from vegetative to reproductive phase. Hence the replanted methods Is not successful and the seed is produced by insitu method, allowing the plants to grow, over winter, flower and produce seed at the same place.
Manures and fertilizers
200:80:100 NPK kg/ha. Nitrogen is applied in 4 equal split doses at different stages of crop at the final field preparation before transplanting, 25-30 days after transplanting, 50-60 days after transplanting and at the bolting.
Spacing
- For dwarf: 60x60 cm, 60x45 cm
- For medium tall: 75x60, 75x45 cm
- For tall: 90x60 cm
Seed rate
For dwarf: 500-750 g/ha
For medium tall: 400-500g/ha
For tall: 350-400g/ha.
Kales are transplanted late in the field during rainy season (Aug-Sept) like other Cole crops, so that the plants grow and over winter during the winter, flower in April and mature in June before the onset of rains. As the first season growth is confined to the production of only the leaves that is not particular regarding adherence to the proper time schedule as is the case with other Cole and root crops for the production of respective economic parts. Late planting results in reduced seed yield due to smaller plants size. Seedlings for transplanting are raised by sowing the seed 4-5 weeks ahead for transplanting.
Before the start of the winter, the plant should be earthen up to give them support. Bolting starts in March and flowering occurs in April. The bolting takes place in response to low temperature during the winter. The inflorescence is like other Cole crops excluding cauliflower and sprouting broccoli but resembles more closely to Brussels sprouts and knol-khol where in it develops directly from the rosette of leaves at the terminal end of the stem. Flowering and seed setting take place satisfactorily between 200 and 300 C. Pollen sterility and low seed setting result at high temperature.
Harvesting: the crop is harvested when 70% pods have changed to yellow but before they are dried.
Seed yield: 300-400kg/ha.
Hybrid seed production in Brassica oleraceae
Because of Self-incompatibility it is a barrier to effective self-fertilization, under field conditions, out crossing is the rule and any given open pollinated variety is highly heterozygous. Inbreeding through bud pollination, usually results in complete loss of vigour in competition for survival.
Self-incompatibility:
The mechanism providing individual isolation is self-incompatibility, which means that pollen of a given plant will not fertilize the ovules of that plant, but is fully effective in fertilizing the ovules of most other plants of the same variety.
Sporophytic incompatibility is the operating system in Brassica for the production of F1 seeds. This method involves two cross compatible lines, each of them are highly self-incompatible. The lines are individually propagated by bud pollination or open pollination at elevated temperatures first by selfing and then by sib pollination in isolation. In hybrid seed production block these lines are planted together in alternate rows to cross-pollination each other. The hybrid seed is harvested from both the parents (Bose et al., 2000)
Problems in exploiting in self-incompatibility:
In species with self-incompatibility continuous inbreeding results in the appearance of new incompatibility relationships, thus causing self-incompatibility. Such mutated forms cannot be used as parents for producing hybrids.
1. Continuous inbreeding in many Brassica crops may lead to complete loss of inbreed lines. It, will therefore, be more desirable if tissue culture techniques for propagation of parental lines are followed. Sib-Mating for maintenance of these lines also prove useful.
2. Psuedo-incompatibility may lead to pure seed in an otherwise hybrid seed.
Reduction of strength of incompatibility by environmental factors e.g. Elevated temperatures may weaken incompatibility or may even break it down. Similar may be the
Methods of F1 seed production:
Single cross:
Line-A Line-B
S11 X S22
Commercial hybrid
(S12)
Double cross:
Line-A x Line-B Line C x Line D
Line AB X Line CD
Commercial hybrid
Triple cross:
Line-A x Line-B Line C Line D x Line E Line F
Line AB x Line C Line DE x Line F
3:1 3:1
Commercial hybrid
The main constraint has been the maintenance and multiplication of these lines for the production of F1 hybrid seed. An attempt to eliminate self-incompatibility temporarily has become rather successful, which has avoided the tedious bud pollination, the self-incompatibility line, if the plant is placed in 2- 5 percent carbon dioxide gas within 2-6 hours of pollination, the self incompatibility is temporarily eliminated.
Break down of self-incompatibility:
1. Bud pollination
2. Delayed self pollination
3. Application of carbon dioxide
4. Treatment of stigma with organic solvents
5. End- season pollination
6. Steel brush pollination
7. Double pollination.
Ratios: 1:1, 2:1, 3:1 or 4:1
Synchronization of flowering:
1. Adjust the time of planting
2. Pinching the main stalk or picking off lower buds.
3. Beehives for pollination increases the seed yield.
Seed storage
The serious problem faced by stored Cole crop seeds is a rapid deterioration which occurs at an increasing rate in uncontrolled storage environments. Seed deterioration cannot be fully arrested, but may be slowed down by storing the seeds in suitable containers such as laminated bags and 700 gauge polythene bags.
Indian minimum seed certification standards
cabbage Cauliflower Knol-khol
FS CS FS CS FS CS
Pure seed (min) 98% 98% 98% 98% 98% 98%
Inert matter(max) 2% 2% 2% 2% 2% 2%
OCS (max) 5/kg 10/kg 5/kg 10/kg 5/kg 10/kg
Weed seed (max) 5/kg 10/kg 5/kg 10/kg 5/kg 10/kg
Germination (%) (min) 70 70 65 65 70 70
Moisture (max) 7.0 7.0 7.0 7.0 7.0 7.0
For vapour proof containers (max) 5.0 5.0 5.0 5.0 5.0 5.0
(Handbook of minimum seed standards)
Seed test methods
Crops Substrate Temperature oC First count Final count breaking dormancy
Cabbage TP, BP 15-25, 20-30 3 10 Light, pre-chilling, KNO3
Cauliflower TP, BP 15-25, 20-30 3 10 Light, pre-chilling, KNO3
Knol-khol TP, BP 15-25, 20-30 3 10 Light, pre-chilling, KNO3
ISTA,2006
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