After reading this article you will learn about:- 1. Origin of Cabbage 2. Production of Cabbage 3. Cytology 4. Floral Biology 5. Qualitative Genetics 6. Cabbage as a Self-Incompatibility Vegetable7. Genetic Resources 8. Breeding Objectives 9. Breeding Methods 10. Resistance Breeding 11. Tissue Culture and Transgenic Technology 12. Selection Techniques 13. Seed Production 14. Varieties.
Contents:
- Origin of Cabbage
- Production of Cabbage
- Cytology of Cabbage
- Floral Biology of Cabbage
- Qualitative Genetics of Cabbage
- Cabbage as a Self-Incompatibility Vegetable
- Genetic Resources of Cabbage
- Breeding Objectives of Cabbage
- Breeding Methods of Cabbage
- Resistance Breeding of Cabbage
- Tissue Culture and Transgenic Technology of Cabbage
- Selection Techniques of Cabbage
- Seed Production of Cabbage
- Varieties of Cabbage
1. Origin of Cabbage:
Modern hard-head cabbage cultivars originated from wild non- heading brassicas somewhere in the eastern Mediterranean and Asia Minor region.
Cabbage belongs to the cruciferae family and the species Brassica oleracea is divided into:
var. acephala – kale and collords
var. fimbriata – curly kale
var. botrytis – cauliflower
var. capitata – cabbage
var. gemmifera – Brussels sprouts
var. gongylodes – kohlrabi
var. italica – sprouting broccoli
All these species have the c genome, contain the same number of chromosomes (2n=2x=18) and readily cross with each other.
2. Production of Cabbage:
Brassica oleracea subsp. capitata (2n = 2x = 18) is one of the most important vegetables grown throughout the world. It has wide adaptability, high disease and stress resistance, high yield potential and strong transporting tolerance.
It is cultivated in many countries, especially those in Europe, North America and Asia. India grows cabbage in approximately 3.10 lakh hectares with an average productivity of 221 q/ha. Cabbage producing major states in India are UP, Orissa, Bihar, West Bengal, Maharashtra and Karnataka.
According to FAO-Statistics-2006, cabbage was grown in 129 countries in 2005 on an area of 3.2 million ha. As per this statistics, China occupied I rank (1.7 mha), followed by India (0.128 mha) and Russia (0.168 mha).
It must be mentioned that as per FAO-Statistics, the term cabbage includes red, white, and savoy cabbages, Chinese Cabbages, Brussels sprouts, green kale and sprouting broccoli. All these belong to Brassica oleracea with the exception of Chinese cabbage which is Brassica rapa. The countries with the highest cabbage productivity are South Africa (640 q/ha) followed by Korea (635 q/ha).
3. Cytology of Cabbage:
Cabbage has a somatic chromosome number of 18 and its genome is c. It is a secondary polyploid with basic chromosome number 6. Three basic chromosomes are present in duplicate and remainder are single i.e. ABBCCDEEF = 9.
Molecular genetic work, using restriction fragment length polymorphisms (RFLPs), suggests that this picture may be an over-simplification. In the course of constructing an RFLP map in B. oleracea, there is evidence of duplicate loci which mapped to different chromosomes.
The order of duplicate loci is often different on different chromosomes. Considerable chromosome rearrangement and restructuring has occurred during the evolution of the species. It might be difficult to identify the possible structure of a lower chromosome number progenitor or to determine if B. oleracea evolved by duplication of loci and complex rearrangements.
Fig. 19.1 shows the interrelationships of various Brassica species, genome designations and chromosome numbers.
All these six Brassica species and radish (Raphanus sativus, 2n=18) have been intercrossed with great difficulty utilizing embryo culture. Thus, the amphidiploids of Fig. 19.1 originated in nature from crosses between the parental species.
4. Floral Biology of Cabbage:
A cabbage flower has four sepals, four petals, six stamens in tetradynamous condition (two short and four long stamens) and a bicarpellary ovary which is superior and has a false septum. Ovules are attached on both the sides of septum. Two active nectaries are located between the bases of short stamens and ovary. The buds open under pressure of rapidly growing petals and become fully expanded in about 12 hrs.
Flowers are slightly protogynous and cabbage is naturally cross-pollinated due to sporophytic self-incompatibility. Pollination is brought about by bees and flies. Bud pollination is effective to achieve selfing. For cross-pollination flower buds expected to open within 1-2 days are emasculated and are pollinated immediately with desired pollen using a brush/flower stamens.
5. Qualitative Genetics of Cabbage:
All the botanical varieties within B. oleracea are cross-compatible with one another and F1 hybrids normally appear intermediate in form between the parental lines. Table 19.1 lists the inheritance of characters which are most easily identified in hybrid seedlings.
The gene list as summarised by Dickson and Wallace (1986) is given in Table 19.2.
6. Cabbage as a Self-Incompatibility Vegetable:
Cabbage is primarily self-incompatible indicated by setting of few seeds only after self- pollination. Genetically, it is sporophytic system where pollen reaction is determined by the genome of the somatic tissue (of the sporophyte) on which the pollen grain develops.
The system of self- incompatibility is characterised by the following features:
(i) Incompatibility is controlled by one S locus having multiple alleles (50-70 alleles in B. oleracea).
(ii) The reaction of pollen is determined by the genotype of the sporophyte on which pollen is produced and therefore is controlled by two S alleles.
(iii) All the pollen of a plant have similar incompatibility reaction.
(iv) The two S alleles may show co-dominance (independent action) or may interact by one being dominant over the other.
(v) The independence/dominance relationships of S alleles in pollen and in the pistil may differ.
(vi) It is usually associated with tri-nucleate pollen and inhibition of pollen occurs at the stigmatic surface.
In contrast to this in gametophytic system of self-incompatibility, the pollen reaction is determined by the genotype of the gametophyte i.e. pollen/egg cell itself and in this system the pollen is bi-nucleate and inhibition of pollen tube occurs in the style.
Various kinds of S allele interactions in a heterozygous genotype (S1S2) with sporophytic self-incompatibility could be as follows:
Dominance – S1 > S2
Co-dominance – S1 = S2
Mutual weakening – No action by either allele
Intermediate gradation – 0-100% activity by each allele
Table 19.3 shows the complexity of the system involving a cross S1S3 X S1S2.
Assessment of Self-Incompatibility:
The usual procedure is to count the number of seeds/pod under self-pollination (bagging of a branch of flowering stalk after removing all open flowers) vs. that under cross or open- pollination.
The disadvantage of this method is that one has to wait for about 60 days till seed reaches to maturity after pollination and secondly, the number of seeds reaching to maturity may also be reduced, by disease, water stress, high temperature in tropics and other stresses.
Ability of fluorescent microscope to display readily those pollen tubes that have penetrated the style provides a direct measure of incompatibility that can be assessed within 12-15 hr. It is adequate and more convenient to be used in a large breeding programme. Pollinated flowers 16-30 hr after pollinations are collected and excised ovaries are softened in 60% NaOH, and placed in aniline blue for staining.
At about 48 hr, after pollination, stigma and style are squashed on a microscope slide. The aniline blue stain accumulates in the pollen tubes and fluoresces when irradiated with UV light thus, under a fluorescent microscope the tubes are visible, whereas the background of stylar tissues is largely unseen.
Penetration of style by none or few tubes indicates incompatibility, penetration by many tubes indicates compatibility and penetration by intermediate number indicates intermediate level of incompatibility.
Permanent S Allele Identities:
The National Vegetable Research Station (NVRS) at Wellesbourne, Warwick, UK has a collection of all known S alleles. The individual breeder may develop homozygous inbreds through selfing in bud stage and tentatively allot the genotypes as SaSa or SbSb.
If SaSa is demonstrated to be reciprocally incompatible with s3s3 maintained at NVRS, SaSa shall be of S3S3 genotype under international nomenclature. However, breeders can also assign S alleles on their own and maintain the inbreds under the designated S allele nomenclature.
Breakdown of Self-Incompatibility:
Various techniques as listed below are available for obtaining a temporary breakdown of the self-incompatibility.
(i) Bud pollination
(ii) Delayed self-pollination
(iii) Grafting
(iv) Heat-shocks
(v) Application of carbon dioxide
(vi) Hormones and protein inhibitors
(vii) Chronic irradiation
(viii) Acute irradiation of styles
(ix) Acute irradiation of pollen mother cells
(x) Tetraploidization-haploidization
(xi) Haploidization-diploidization
(xii) Treatment of stigma with organic solvent
(xiii) End-season pollination
(xiv) Steel brush pollination
(xv) Double pollination
(xvi) Electric aided pollination
Biochemical Basis of Self-Incompatibility in Brassica:
Nishio and Hinata (1977) carried out polyacrylamide gel isoelectric focusing to study buffer soluble proteins of stigmatic homogenates of six S-allele genotypes in Brassica oleracea.
Six strains with S-alleles as S2S2, S7S7, S13S13, S22S22, S39S39 and S45S45 were provided by Institute for Horticultural Plant Breeding, the Netherlands. From open flowers, 50 stigmas were homogenized by a mortar and pestle with 0.1 ml phosphate buffered saline (0.01 M phosphate buffer pH 7.1 plus 8.5 g/1 of NaCl).
The homogenate was centrifuged for 20 minutes at 10,000 rpm and 20 of the supernatant was introduced to each glass tube. Proteins were extracted from anthers, leaves and seedlings. Polyacrylamide gel electrophoresis and isoelectric focusing were used. However, results from isoelectric focusing were found to show S-allele specificity ascribable to a combination of the protein bands.
In this method 7.5% acrylamide gel containing ampholine (pH 3.5-10.0) was used. Sample gel was faced to the anode side. Anode and cathode vessels were filled with 0.02 M HCl and 0.02 M ethylene diamine, respectively. Electrophoresis was carried out under constant voltage, 200 V, for 3 hours at 5°C.
The gels after running were immersed in 12.5% trichloroacetic acid overnight, and washed in 7% acetic acid 4-5 times to remove ampholine. The gels were stained with 0.2% Coomassie Blue in ethanol-water-acetic acid (45 : 45 : 10) for 45 minutes and then de-stained with ethanol water acetic acid (25 : 65 : 10) and then stored in 7% acetic acid.
It is known in Brassica that S-allele specificity appears in mature stigmas but not in young ones. Therefore, the basic proteins of the stigmas were compared between young and old. The densitometry of the band pattern of young and mature stigmas in S13S13 homozygotes is shown in Fig. 19.2.
The diagrammatic representation of stigmatic proteins of different S-homozygotes as observed under isoelectric focusing by Nishio and Hinata (1977) is shown in Fig. 19.3. Perusal of Fig. 19.3 indicates that S39S39 hand d, e, f, g and i bands, while S13S13 had e, g, h, i, and trace of d, etc. The band e was observed in every homozygote.
All the S-homozygotes were differentiated by the combination of these bands. There is a possibility that these bands are not S-allele specific but are products of the genetic backgrounds of the S-homozygotes. Similar patterns of zymograms were, however, found in stigmas of different S-homozygotes for esterase, acid phosphatase, and peroxidases.
Further, no discernible specificity was found in leaf and seedling proteins of different S-homozygotes by the isoelectric focusing. It may be inferred, therefore, that background of the material was not so different between S-alleles.
The protein bands focused in the present method appeared in the course of the maturation of stigmas and the time of appearance coincided with the phenotypic expression of self-incompatibility. The balance of evidence suggests, therefore, that some, it not all, of the fractions revealed by the isoelectric focusing are directly related with the specificity of S-alleles.
These stigmas extracts have now been specifically recognized as S-locus specific glycoproteins (SLSG) and exhibit extensive polymorphisms that are most easily detected on is electric focusing gels.
Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of stigma extracts, SLSGs migrate as a complex of several closely spaced molecular-weight species differing by approximately 2000 Daltons.
7. Genetic Resources of Cabbage:
Plant genetic resources are the backbone of any crop breeding programme. Since 1982, the IPGRI has sponsored several missions to collect wild Brassica species.
According to IPGRI policy, each sample is split into 3 parts which are stored at:
1. Poly-tech University, Madrid, Spain
2. University of Tohoku, Sendai, Japan
3. Gene Bank of country from where samples are collected
In USA, the National Plant Germplasm System (NPGS) is a cooperative effort by public (State and Federal) and private organisations to conserve plant genetic resources. As of 16 July 2006, the NPGS holds a total of 471318 accessions that represent 216 families, 1914 genera and 11756 species. Most Brassica species are conserved at Plant Genetic Resources Unit (PGRU) at Geneva Campus, (New York) of Cornell University.
In 1982, Prof. Williams established the Crucifers Genetics Cooperative (CrGC) at the Univ. of Wisconsin to manage germplasm of Brassicaceae. European brassica database (Bras -EDB) has been developed by the centre for Genetic Resources, the Netherlands. Other European countries that maintain collections of cabbages and kales are Bulgaria, Croatia, Czech Republic, Hungary, Poland, Russia, Switzerland, and Turkey.
According to Swarup and Brahmi (2005), there are sizeable collections of cole crops in Israel. Ethiopia, South Africa, India. Philippines and Taiwan. The IARl-Regional Station. Katrain, Kullu Valley, Himachal Pradesh is actively engaged in cabbage germplasm maintenance and breeding research in India.
8. Breeding Objectives of Cabbage:
1. High yield
2. Longer staying capacity in field after head formation/greater field holding capacity
3. Desirable heal weight (1 – 1.5 kg)
4. Early head formation/early maturity
5. Storage ability
6. Head shape and colour as per preference of consumers (essentially round heads, light green-green colour)
7. Less proportion of outer/wrapper leaves
8. Short and narrow cone
9. Firm head with short internal stem
10. Ability to tolerate frost
11. Resistance to diseases:
i. Black rot (Xanthomonas campestris)
ii. Alternaria leaf spot (Altemaria ssp.)
iii. Black leg (Leptosphaeria maculans)
12. Tolerance to insect – Pests
– Diamond – back moth (Plutella xylostella)
9. Breeding Methods of Cabbage:
Open-pollinated Cultivars:
(i) Mass selection
(ii) Inbreeding (in cultivars with low level of self-incompatibility and inbreeding depression)
Hybrid Cultivars:
The self-incompatibility is used to produce hybrid seeds in cabbage and other cole crops, namely, cauliflower, broccoli, Brussels sprouts, and kale. The individual plants are self-pollinated through bud-pollination. Selection is applied for desirable characters and strong level of self-incompatibility.
This way several self-incompatible, but cross-compatible inbreds having different S-alleles are developed as illustrated in (Fig. 19.4).
Such S1S1 and S2S2 lines are planted in alternate rows in isolation and seed set on each line will be mostly hybrid seed where cross-fertilization is brought about by pollinating insects, mostly bees. The cross compatibility between inbreds of S1S1 and S2S2 assures the production of F1 hybrid seed.
Cabbage hybrids could be of following kinds:
Single Cross:
This is a cross between two inbreds. Single cross hybrids are more uniform than hybrids produced from double/top crosses.
Double Cross:
A cross between two single crosses is known as double cross. Four homozygous inbreds are required to produce a double cross, for example, (S1S1 x S2S2) X (S3S3 x S4S4). In this system, seed is harvested from both the single crosses which themselves are vigorous and therefore, cost of hybrid seed is reduced.
Top Cross:
This is a cross between a single self-incompatible inbred line as female and a good open- pollinated cultivar as pollen parent. Till, late eighties, most of the cabbage hybrids produced in United States were top crosses.
Problems in the Breeding of F1 Hybrids:
(i) Depression by inbreeding
(ii) Sister-brother fertilization within parental lines creating the problem of ‘sib’ seed contaminants
(iii) Reduction of incompatibility by environmental conditions
(iv) Restriction of pollination within parental lines by bees instead of random movement of bees
Depending upon the parental lines and conditions during seed production, the proportion of such sib seed may vary from nil to as much as 80%. The usual method of assessment of proportion of sibs is to grow plants from a seed sample until they are sufficiently developed to adjudge phenotypic difference between sibs and hybrids.
The time taken may vary from a few weeks if obvious differences are apparent at the seedling stage, to from 10-12 weeks if difference between the hybrid and parents cannot by adjudged until the adult plant stage. In such situations, isozyme analysis as standardised by Wills (1979) has been shown to have several advantages and offers a practical alternative to traditional methods.
In this method extracts of seed of Brassica oleracea L. cultivar were separated by electrophoresis on polyacrylamide gels and stained for 14 enzymes, namely:
i. Acid phosphatase
ii. Alcohol dehydrogenase
iii. Alpha amylase
iv. Carbonic anhydrase
v. Carboxyl esterase
vi. Catalase
vii. Catechol oxidase
viii. Beta galactosidase
ix. Beta glucosidase
x. Isocitrate lyase
xi. Lipase
xii. Leucine amino peptidase
xiii. Peroxidase
xiv. Pyrophosphatase
The electrophoresis was carried out on 10% polyacrylamide gel slabs with gel buffer 0.37 M tris-HCl, pH 9.1 and electrode buffer 0.01 M tris-glycine, pH 8.3. Acid phosphatase activity was found in 3 anodal zones. The fastest zone stained too faintly to permit consistent analysis. The densely staining slowest zone could not be resolved into discrete bands.
The intermediate zone was highly active and except for one cultivar, all seeds showed either one or two of the total five bands recognized. Hybrid seeds from crosses between inbreds with different single bands expressed both parent bands as illustrated in Fig. 19.5. Fitzgerald (1997) have described a technique for determining sib-proportion and aberrant characterisation in hybrid seed using image analysis.
Breeding and Utilisation of Self-Incompatible Lines:
It is easy to breed self-incompatible lines of cabbage through continuous self-pollination and selection. When two self-incompatible lines are used as parents to produce hybrids, the reciprocal crossed seeds can be harvested as hybrids. In 1950, the first cabbage hybrid in the world was developed in Japan using self-incompatible lines. This hybrid was known as Nagaoka No. 1.
The superior self-incompatible lines for hybrid seed production should have following characters:
1. Stable self-incompatibility
2. High seed set after self-pollination at bud stage
3. Favourable economic characteristics
4. Desirable combining ability
5. Almost all cabbage hybrid seeds are produced using self-incompatible lines all over the world. Now CMS system is also being used.
Bud Pollination:
The basic seed of parental inbred lines is obtained by hand selfing at bud stage. The bud top is removed by tweezers and strippers to expose stigma which is then pollinated with pollen collected from the same plant/line. The seed production plot of parental inbred lines is covered with net to avoid contamination by bees or other insects.
Pollen grains are collected afresh from the opened flowers on the same day. The mixed pollen collected from the same line should be used for pollination to avoid viability depression from continuous selfing.
If the bagging isolation is applied to multiply the basic seeds, the flowering branch is covered with paraffin bag/muslin cloth bag before the bud opens. The bud size should not be too small or big. Bud pollination done 2-4 days prior flowering gives the highest seed set.
Propagation of basic seeds of incompatible lines by bud pollination is labour-intensive and costly. In consideration of this disadvantage, the electricity-aided pollination, wire brush pollination, thermal-aided pollination, CO2 enrichment, etc., have been suggested.
However, each one of these has its limitations and has not been used on commercial scale. Spraying a solution of 5% common salt has been used to overcome the self-incompatibility and increase the seed set by scientists in China. This method has been successful in the propagation of basic seeds.
Special Considerations for F1 Hybrid Production Plots:
1. Isolation distance of at least 2000 m from cauliflower, kohlrabi, broccoli, kale, Brussels sprouts, etc.
2. Provision of approximately 15 honey bee boxes/ha
3. Building-up framework through appropriate staking to prevent lodging
4. Control of insects and diseases
5. Synchronized flowering of the parental inbreds
6. Planting ratio of 1: 1 for the parental inbreds
7. Although harvested seeds from both parents can be mixed-up, it is better to harvest seeds from both the inbreds separately to improve seed uniformity.
10. Resistance Breeding of Cabbage:
Cabbage Yellows:
It is caused by Fusarium oxysporum. It is soil borne, vascular wilt favoured by warm soil temperatures with optimum at 28°C. There is progressive yellowing followed by brown necrosis, stunted plant growth with premature leaf drop. Type A resistance is determined by one dominant gene and is not influenced by temperature.
Type B resistance is conditioned by several genes and breaks down at temperature above 22°C. Screening for A type resistance is done by dipping young seedlings in an inoculation suspension and then growing them at 27°C. In 2-3 weeks susceptible plants will be dead.
Black Rot:
It is a bacterial disease caused by Xanthomonas campestris. Resistance was reported in Early Fuji. It is seed borne, shows vascular bacteriosis causing yellowing of leaves. Resistance is controlled by a major gene ‘f’ plus 2 modifiers, one dominant and one recessive.
For artificial inoculation a bacterial suspension is sprayed on well-developed plants early in morning. This introduces bacteria into guttation droplets. In 2-3 weeks, susceptible plants will develop large lesions on leaf margins and blackening through veins of leaf and stem. Resistant cultivars will show slight necrotic infection at leaf margins.
11. Tissue Culture and Transgenic Technology of Cabbage:
Anther culture and microspore culture have been reliably used to produce double haploid lines. The double haploids allow rapid establishment of homozygous lines from wide crosses. Successful anther and microspore cultures have been reported for several crops in B. oleracea including cabbage. Double haploids have been of importance in mapping of genes and to detect QTLs.
Transgenic cabbage and kale cultivars with enhanced resistance have been produced, while transgenic canola (B. napus) has been commercialized in USA, there are no GM vegetable brassica. The most general approach for genetic transformation in cabbage has been through Agrobacterium tumefusiens and A. rhizogenes.
The explant for transformation in cabbage is leaf petiole, hypocotyl and leaves. Mostly, transgenic cabbages have foreign gene from Bacillus thuringiensis (Bt gene). Bt genes have been expressed in all the major groups of brassica crops including kales and cabbages.
Private sector seed companies have produced cabbage Bt transgenics and field level evaluations have also been done. However, no Bt brassicas have been released commercially.
Transgenic cabbage resistant to P. xylostella (diamond back moth) has been developed through A. tumefaciens – mediated transformation with B. thuringiensis (Bt) cry genes. The genes used to produce transgenic cabbage against DBM are Cry I Ac, cry 1 Ab3 and cry 1 Ab including cry 1 Ab transgenic in India by Bhattacharya (2002). Resistance induced has been partial with delayed insect development rather than insect mortality.
Protocols for tissue culture and Agrobacterium tumefaciens-mediated transformation of cabbage have been developed. Factors important for transformation include pre-culture and co-culture of explants on a callus induction medium, induction of Agrobacterium virulence with a minimal medium containing acetosyringone, use of an appropriate amount and initial application of selective agents.
A synthetic Bt toxin gene, cry1 Ab3, and a wild-type gene, crylla3, have been used for transformation. All cabbage plants transgenic for cry1 Ab3 provided 100% mortality of the larvae of the diamondback moth, whereas cabbage plants transformed with crylla3 were susceptible to the larvae.
Northern analysis showed that the transgenic cry1 Ab3 plants produced a full-length transcript of gene, whereas the cry1 1/a3 plants produced a truncated transcript, leading to the susceptibility of these plants to the diamondback moth.
Thus, cabbage has been transformed to express Bt ICPs for control of the diamondback moth but here transgenic cabbage has been used primarily to evaluate management strategies, although seed companies are evaluating the potential for commercialisation.
Great care must be taken to develop such plants because DBMs have already developed high levels of resistance in some areas to foliar applications of Bt products containing cry1 A and cry1 C toxins.
12. Selection Techniques of Cabbage:
Head Shape:
Pointed, flat, or round heads are preferred depending upon consumers’ appeal. Generally, round heads with internal solidity are selected. Shape of head is usually expressed in terms of polar and equatorial diameters of head and their ratio as given below:
Spherical head – ratio is 0.8 -1
Drum head – ratio is 0.6 or less
Conical head – ratio is more than 1
Heading Vs Non-heading:
The wrapper leaves surrounding the terminal buds should be tight enough to form a head.
Head Size:
Medium sized heads are generally desirable.
Plant Height:
A short stem is desirable because tall stemmed plant will not be able to bear the weight of the cabbage head and consequently, tall plant is likely to fall.
Core Width:
A narrow core is desirable.
Core Length:
A short core less than 25% of the head diameter is preferred.
Core Solidity:
A soft core is preferred over tough one, particularly in cabbage meant for processing.
Axillary Heading:
This is undesirable and is assessed by splitting the head vertically through the core.
Storage ability:
Longer storability is desirable. It is positively correlated with dry matter contents and late maturity. Dry matter could be assessed by sampling about 200 g portion of head excluding core tissue and measuring the fresh and dry weights of the sample.
Head Compactness:
By applying pressure on head by thumbs, compactness of the head can be judged to some extent. Following 4 methods are more useful.
(i) Examination of the position of the uppermost wrapper leaf indicates compactness. If it covers two third or more area of head, the head is considered to be compact.
(ii) Measuring the length of core inside the head by cutting a longitudinal section also indicates compactness. A compact head has relatively small core.
(iii) Compactness of the head can also be adjudged by the following formula given by Pearson.
Z = C X 100 /W3
Where Z = an index of compactness
C = net weight of the head
W = average of the lateral and polar diameters of the head. A higher value of Z indicates more compact head.
(iv) Net weight of head (without stalk and non-wrapper leaves) also gives a fair idea of compactness. More the weight, higher is the compactness.
Frame of the Plant:
This is the maximum spread of plant at maturity. Usually smaller frames are preferred.
13. Seed Production of Cabbage:
Isolation Distance:
1. Breeder/Foundation seed – 1600 m
2. Certified seed – 1000 m
Cultivar Description of Cabbage:
There are open-pollinated and F1 hybrid cultivars. The following outlines for cultivar descriptions of cabbage are based on the guidelines for DUS tests produced by UPOV (1992) and described by George (1999).
1. Plant height: very short, short, medium, tall or very fall
2. Plant:
Maximum diameter: small, medium or large
Length of outer stem: short, medium or long
Attitude of outer leaves: erect, semi-erect or horizontal
3. Outer leaf: Small, medium or large
Shape of blade: broad elliptic, broad ovate, circular, transverse broad elliptic or broad obviate
Profile of upper side of blade: concave, plane or convex
Blistering: absent or very weak, weak, medium, strong or very strong
Size of blisters: small, medium or large
Crimping (savoy cabbage only): weak, medium or strong
Colour (with wax): yellow-green, green, grey-green, blue-green or violet
Intensity of colour: light, medium or dark
Green flush (red cabbage only): absent or present
Waxiness: absent or very weak, weak, medium, strong or very strong
Undulation of margin: absent or very weak, weak, medium, strong or very strong
Incisions of margin: absent or present
Reflex-ion of margin: absent or present
4. Head:
Shape of longitudinal section: transverse narrow elliptic, transverse elliptic, circular, broad elliptic, broad obovate, broad ovate or angular ovate
Shape of base in longitudinal section: raised, level or arched
Length: short, medium or long
Diameter: small, medium or large
Position of maximum diameter: towards top, at middle or towards the base
Cover: uncovered, partially covered or covered
Blistering of cover leaf (savoy cabbage only): absent or very weak, weak, medium, strong or very strong
Reflex-ion of margin of cover leaf: absent or present
Colour of cover leaf: yellow-green, green, grey-green, blue-green or violet
Intensity of colour of cover leaf: light, medium or dark
Anthocyanin coloration of cover leaf (white and savoy cabbages only): absent or very weak, weak, medium, strong or very strong
Internal colour: whitish, yellowish, greenish or violet
Intensity of internal colour (red cabbage only): light, medium or dark
Density: very loose, loose, medium, dense or very dense
Internal structure: fine, medium or coarse
Length of interior stem (in relation to length of head): short, medium or long
5. Time of harvest maturity (in specific season): very early, early, medium, late or very late
6. Time of bursting of head after maturity: early, medium or late
7. Resistance to race 1 of Fusarium oxysporum f. sp. conglutinans
8. Method of seed production: open-pollinated or hybrid
Seed Yield:
1. Approximately 700 kg/ha
2. 1000 seed weight -3.3 g
3. Seed multiplication ratio – 100
14. Important Varieties of Cabbage:
Based on maturity, head shape, head size, and leaf colour and shape cabbage varieties have been classified into different groups:
(i) Wakefield or Winningstadt group
(ii) Flat Dutch or drumhead group
(iii) Copenhagen market group
(iv) Savoy group
(v) Danish ball head group
(vi) Alpha group
(vii) Volga group
(viii) Red cabbage group
In India Copenhagen market group (early round headed varieties with compact heads having few outer leaves and small core) and Flat Dutch group (flat heads, large outer leaves) are common.
Copenhagen Market:
It has round heads which are bigger than that of Golden Acre. Head weight is 1.5-3.0 kg. It takes 75-85 days for head formation.
Golden Acre:
An earliest variety, selection from Copenhagen market, 60-65 days from transplanting to head formation, 1-1.5 kg head, solid head with short core, prone to cracking under delayed harvesting, recommended by Indian Agricultural Research Institute, New Delhi.
Pride of India:
An introduction recommended by Dr. Y.S. Parmar University of Horticulture and Forestry, Solan, bigger head (1.5-2.0 kg). Basically, it is also a selection from Copenhagen Market.
Pusa Mukta (Sel-8):
Developed from an inter-varietal cross of EC 24855 and EC 10109 at IARI, regional Station, Katrain, Kullu Valley, Himachal Pradesh, early with medium sized round heads, slightly late than Golden Acre, resistant to black rot, identified by all India coordinated vegetable improvement project and released by central sub-committee on Crop Standards, Notification and Release of Varieties.
Pusa Ageti:
It is the first tropical variety developed for cultivation under high temperature conditions. It can grow and form heads at a temperature of 15-30°C. It takes 70-90 days for head formation after transplanting. It has grey-green foliage and flattish-round heads. Head weight is 600-1200 g. Its seeds can be produced under sub-tropical conditions of north-Indian plains.
Pusa Drum Head:
Developed by selection at Katrain, early in Drum Head group, big sized flat heads (3-4 kg) in 70-75 days after transplanting, resistant to black leg (Phoma lingam).
September:
An introduction from the then German Democratic Republic under INDO-GDR Project in Nilgiri Hills. The initial seeds were received through NSC and showed wide variation. The same has been purified at Katrain. Heads are solid, flattish round to slightly oblong weighing 3-5 kg. The foliage is dark green with wavy margin. It is popular in Nilgiri hills of Tamil Nadu and has been recommended by Tamil Nadu State Department of Horticulture.
Savoy cabbage having blistered leaves is not popular in India. The heads are pointed, round and flat. Commonly catalogued variety is Chieftain. Red cabbage group (variety-Red Acre) is also not popular in India. Some promising hybrids are Bajrang, Swarna, Sudha, Sri Ganesh Gol, Bahar, Pragati, Hari Rani Gol, Kranti, etc. in India.
Roughly 100 ton OP cabbage seed and 50 ton hybrid cabbage seed is marketed in India. All hybrid cabbages are imported. Some of the cabbage hybrids imported from abroad (China, Japan, Korea, Taiwan) are tropical types and hence, cabbage is available in Indian market round the year.