Lecture No: 09

Centers of origin – Distribution of species – Wild relatives – Breeding objectives

and procedures of conventional and innovative approaches in different
horticultural crops – Marigold and Gerbera

MARI GOLD (Tagetes erecta L). (2n = 24)

Introduction
Marigold (Tagetes erecta L., Asteraceae) is grown as an ornamental crop for loose
flowers and as a landscape plant, as well as source of pigment for poultry feed. Flowers are
sold in the market as loose or after making into garlands. Other than loose flowers, it can also
be used as cut flowers. Marigold especially is used for beautification and also in landscape
plans due to its variable height and colour of flowers. It is highly suitable as a bedding plant,
in a herbaceous border and is also ideal for newly planted shrubbery to provide colour and fill
spaces. French marigold is ideal for rockeries, edging, hanging baskets and window boxes.
Origin: Mexico
Distribution: USA, Europe India etc. In India Maharashtra, West Bengal, Karnataka, Tamil
Nadu and Andhra Pradesh.
Species, Types and Cultivars
Species: There are about 33 species of the genus Tagetes. The characters of important species
(Bailey, 1963) are given below:
Tagetes erecta (African marigold): The plant is hardy, annual about 90 cm tall, erect and
branched. Leaves are pinnately divided and leaflets are lanceolate and serrated. Flowers are
single to fully double and large sized with globular heads. The florets are either 2-lipped or
quilled. Flower colour varies from lemon yellow to yellow, golden yellow or orange.
Targets patulo (French marigold): A hardy annual, about 30 cm tall, forming a bushy plant.
Foliage is dark green with reddish stem. Leaves are pinnately divided and leaflets are linear
lanceolate and serrated. Flowers are small, either single or double, borne on proportionately
long peduncles. The flower colour varies from yellow to mahogany-red.
Tagetes tenuifolia (Syn. Tagetes signata): It is an annual with a branching habit. Leaves are
pinnately divided into 12 oblong, linear, sharply serrated segments. Flowers have 5 rays,
yellow, roundish and obovate. Tagetes signata cv. Pumila is a dwarf, brushy and grows less
than 30 cm. Flowers are bright yellow and small but numerous.
Tagetes lucida (Sweet scented marigold): The plants of this species are tender, perennial.
Leaves are sessile, small and lanceolate. Flowers usually are 2-3 rayed, produced in dense,
terminal corymbs. The flowers have much more agreeable odour than other species.

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Tagetes lacra: It was discovered in California. The plant grows upto 120-150 cm in height
and flowers profusely. Flowers are yellow in colour.
Tagetes lemmonii: It is a shrubby plant, grows up to 60-70 cm. Leaves are slender, opposite;
leaflets about 2-3 cm long. Flowers are showy and 2-3 cm in diameter.
The other species grown in gardens are Tagetes minuta, Tagetes pusilla and Tagetes
corymbosa. In India, however, the cultivation of Tagetes erecta and Tagetes patula
dominates.
Breeding objective:
1. Compact and dwarf growth habit
2. Uniform response to environment
3. More flower yield.
4. Free from diseases and pests
Breeding Methods:
1. Introduction:
A wide array of germplasm was collected At N.B.R.I., Lucknow and Punjab
Agricultural University, Ludhiana from exotic sources. In African marigold,. 5 varieties,
namely Alaska, Doubloon, Fire Glow, Golden Jubilee and Yellow Fluffy were recommended
for loose – flower production, whereas eight varieties viz., Geraidine, Golden Climax Giant,
Orange Fluffy, Orange Mums, Sovereign, Sun Giants, Super Chief Double and Yellow
Climax were found suitable for cut flower purpose at N.B.R.I. Lucknow, PAU, Ludhiana
recommended 2 varieties like Giant Double Afrian Orange and Climax of Afrian marigold
and 3 varieties Rusty Red, Butter Scotch and Red Brocade of French marigold for loose
flower production and 3 varieties, namely, Valencia, Sussana and Tetraploid for bedding
purpose.
2. Selection: A large number of varieties of African marigold were collected at IARI, New
Delhi. Since, most of the varieties were in heterozygous condition, single plant selections
were made in the basis of desirable attributes. As a result of these efforts, few promising
selections have been developed, which are in pre-release stage.
3. Hybridization: Hybridization between distantly related types is the most effective and
commonly employed tool to induce variation so as to improve the existing cultivars and
evolve new, high yielding and better quality of genotypes. Different principles of breeding
have successfully been used in marigold, which resulted in new cultivars and present day F 1
hybrids.

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Inter-Varietal Hybridization: In well-planned breeding studies, Singh and Swamp (1972)
observed appreciable heterosis. Attempts were made to develop F 1 hybrids in marigold
because F1 hybrids are considerably; uniform and capable of producing large blooms with
high yield potential. In addition, they are characterized by their semi-tall nature with
excellent large full double flowers. For the last 20 years, F 1, hybrid seeds of Tagetes erecta
are available. Climax was the first F 1, hybrid to be released. A number of other F 2 hybrids are
also available in the market.
Inter-Specific Hybridization: The inter-specific hybridization between Tagetes erecta x
Tagetes tenuifolia and Tagetes erecta x Tagetes jaliscensis has been done by Towner (1961,
1962). Recently, inter-specific hybridization between Tagetes erecta x Tagetes patual has
been carried out which finally led to evolution of Red and Gold hybrids. These hybrids are
dwarf-like French marigolds but produce bigger flowers like that of African marigolds in
large number.
4. Pedigree Breeding: A large number of single crosses were made involving genetically
diverse inbred lines / open pollinated varieties. Selections started from F 2 generation onwards
till they attained homozygosity. As a result of these studies, a few very promising improved
lines have been developed, which are in pre-release stage.
5. Polyploidy: Studies on the nature and the limit of polyploidy in marigolds were carried out
at N.B.R.I., Lucknow. Interspecific crosses between T. erecta (2n=24) and T. patula (2n=48)
were attempted and interspecific triploid hybrids (2n=36) were produced. It was inferred that
hexaploidy may not be successful in marigold as the highest ploidy level in about 50% of the
species of the genus Tagetes is tetraploidy.
6. Male sterility: Male sterility in marigold is of two kinds: (1) apetalous, and (2) double-
flowered. Apetalous sterility is preferred to full double flowers because the latter type is
prone to break down and it gives rise to a few disc florets at later stages which may be due to
either age of plants or environmental factors. However, apetalous flowers are less attractive
to pollinating insects. Male sterility is governed by a recessive gene and is incorporated into
the seed parent. It is maintained by crossing the heterozygous plants with the sterile ones.
African marigold (hybrid seed production)
In African marigold, genic male sterility system is being used for F 1 hybrid seed
production. There are two types of male sterility in marigold, that is, apetalous from (with no
stamens) and true double form (produces no anthers in the disc florets). Apetalous type of
male sterility has greater liability and is being used for the production of F 1 hybrid seeds on a
commercial scale in the U.S.A., U.K., Holland, France, etc. The apetalous type of male

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sterility is controlled by recessive alleles. Thus, a male sterile plant has a genetic constitution
of ms (homozygous recessive), while male fertile plants may be of Ms Ms or Ms ms
genotypes. The heterozygote ms ms will segregate to give 1 Ms Ms:2 Ms Ms Ms ms:1 ms
ms, the usual ratio for a single gene, but both homozygous Ms Ms and ms ms) will, of course,
breed true (except that the latter will produce no pollen to allow to breed further).
Therefore, for use as a parent in F 1 hybrid production, the male sterile line is
perpetuated by back-crosses of double recessive (ms ms) male sterile by heterozygous male
fertile (Ms ms) maintainer. In the subsequent generations, 50 per cent of the progeny will be
male fertile Ms ms, while the other 50 per cent will be male sterile ms ms. Male sterility
phenomenon can be incorporated into standard varieties though five or six generations of
back-crossing.
For the actual production of F1 hybrid seed in the field, the back cross generation us
inter-planted with the other parental lines (which is a nomal male fertile inbred) and
heterozygous male fertiles occurring in back-cross generation should be removed as soon as
identification is possible, thus leaving male sterile plants only. the male sterile plants can be
identified in the early stage by the shape of sunflower buds as these plants have pitcher type
of flower buds, whereas the male fertile plants have normal flower buds.
To summarise, the mechanisms of using genetic male sterility for F 1 hybrid seed
production under open field conditions require (1) a normal fully fertile inbred line and (2)
and inbred line which is maintained by crossing together known heterozygous (Ms ms) and
male sterile (ms ms) plants. Seeds should always be harvested from ms ms plants. The cross
of ms ms x Ms ms should be repeated in every generation, as it will segregate in 1 fertile 1
Sterile ratio. A ratio of male sterile to pollinating fertile line is dependent on the size of
hybrid block, but ratio of 3 male sterileline 1 male fertile has proved to be the optimum.

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 GERBERA (Gerbera jamesonii)
Gerbera commonly known as Transvaal Daisy, Barbeton Daisy or African daisy. It is
highly suitable for beds, borders pots and rock gardens. The wide range of colours and the
attractive shape of flowers suit very well in flower arrangements. The cur blooms have long
vase life.
The breeding of gerbera started in 1887 when R.I. Lynch crossed Gerbera jamesonii
and Gerbera viridifolia. The hybrid was named Gerbera contabrigensis known today also as
Gerbera hybida. Majority of the present commercial cultivated varieties originated from
crossing the progenies of these two species.
Breeding Objectives:
Taking into account the importance of Gerbera as a cut flower and for garden
purposes the following objectives are suggested in breeding of Gerbera.
1. Uniformity and compactness of growth of plants
2. Earliness in flowering
3. More number of flowers / plant
4. Development of double coloured flowers
5. Uniform long and sturdy stalks
6. Yield, period of flowering
7. Vase life and
8. Resistance to pests and diseases.
Breeding Methods:
Since Gerbera can be propagated both sexually (seeds) and asexually (Suckers). The
breeding methods suitable for both types can be followed they are
1. Clonal Selection
2. Synthetic vartiety
3. Polyploidy
4. Hybridization:
Numerous cultivars of Gerbera that are known today have been developed through
hybridization. For breeding purposes the flowers can be divided into two groups based on ray
floret width namely florets narrower that 5 to 55 mm and those wider than 55 mm. Breeding
for flowers with fine rays is done within the first group. For wide rays crossing is done within
the second group (or) hybridization between the second group and the less narrow types of
the first group.

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5. Mutation Breeding:
X-ray irradiation (20 GY) was tried on plants propagated in-vitro. Flower shape and
size and foliage characters were affected but changes in flower colour were rare. Ethyl
methyl sulphonate (EMS) was better than sodium hydrazide in inducing gene mutation.