After reading this article you will learn about:- 1. Origin of Turnip 2. Production of Turnip 3. Genetics 4. Breeding Objectives 5. Hybridization Technique 6. Breeding Methods 7. Varietal Descriptors 8. Varieties.
1. Origin of Turnip:
Turnips are believed to have originated as a crop in the cooler parts of Europe, presumably from biennial oilseed forms. The crop has been under cultivation since ancient times and was known to Greeks and Romans at the beginning of the Christian era. It was introduced into Britain from France by the Romans, and into North America by the early European settlers in the 17th century.
2. Production of Turnip:
Turnip (Brassica rapa L., 2n = 2x = 20, formerly B. campestris subsp. rapifera) belongs to the large Brassica family and bears similar yellow (and occasionally white) flowers. It does not cross readily with the oleracea (cabbage types) and belongs to a separate species, B campestris. Another crop swede (B. napus L. var. napobrassica) is directly related to turnip.
The swede is an amphidiploid with 38 chromosomes and is known to be a natural hybrid between B. campestris (2n = 20) and B. oleracea (2n = 18). Neither of the ancestral types is known accurately, but it is thought that the cross occurred numerous times where the two species overlap in their natural habitat (from Western Europe to Eastern Asia).
The interspecific cross has been synthesized by several workers, but the result is not noticeably swede-like. Cross-incompatibility between the parental species is quite marked and pollen tubes tend to become distorted in the style.
Any successful fertilization seems to result in the production of a sterile hybrid. Both are cultivated as annual root crops for both animal and human consumption. The storage organ is a swollen hypocotyl. In India turnip is cultivated in approximately 2,500 ha with annual production of 50,000 tons.
3. Genetics of Turnip:
Turnip has a sporophytic system of self-incompatibility.
From qualitative genetic viewpoint, limited information as summarized by Pink (1993) is as follows:
Flesh colour – White dominant to yellow and monogenic
Skin colour – Two independent loci, both the dominant genes give rise to purple phenotype
Cream corolla – Single recessive gene (cr)
Light yellow corolla – Single recessive gene (ly)
Dark yellow corolla – Single recessive gene (dy)
Cupped petal – Single recessive gene (cup)
Apetalous – Single recessive gene (pl)
Puckered leaf – Single recessive gene (pkl)
Anthocyaninless hydathode – Single recessive gene (ahd)
Anthocyaninless bud tip – Single recessive gene (ab)
Anthocyaninless anther tip – Single recessive gene (aa)
Anthocyaninless style tip – Single recessive gene (as)
Rolled petal margin – Single dominant gene (Ropm)
Bolting – Two major additive genes
Club root (Plasmodiophora brassicae) resistance – Three independent dominant genes
Powdery mildew (Erysiphe crucifer arum) resistance – Quantitative inheritance, partially recessive genes
Turnip mosaic virus resistance – Single dominant gene
4. Breeding Objectives of Turnip:
1. Early days to attain marketable root size
2. Root colour as per consumers’ preference, white, purple types more liked in India than golden ball types
3. Stump rooted varieties with thin tap root and non-branching habit
4. Slow bolting habit
5. Appropriate dry matter (8-9%) in roots
6. Resistance to club root, powdery mildew, turnip mosaic virus, white rust, phyllody, cabbage root fly, turnip root fly and aphids
5. Hybridization Technique of Turnip:
Turnip has strong sporophytic system of self-incompatibility and is thus, highly cross- pollinated. Due to this, there is no need for emasculation and crosses can be made by enclosing flower heads from 2 compatible plants in a muslin bag with blowflies as pollinators.
Before enclosing 2 flower heads in one bag, open flowers if any should be removed. Selfing can be accomplished by application of fresh pollen on style after removing the stigma. Sodium chloride and carbon dioxide could also be used to overcome self-incompatibility.
6. Breeding Methods of Turnip:
This method of breeding has been commonly employed to breed several open-pollinated cultivars. Plants from selected roots are allowed mass-pollination in isolation.
There has been greater interest among breeders to produce hybrid cultivars of fodder swedes utilizing self-incompatibility. However, the same has not been achieved in case of horticultural types. Heterosis has been reported for several characters including the yield of root and leaf.
Japanese breeders have been successful in developing several F1 hybrid cultivars of white turnip. There has been some progress in breeding of F1 hybrid turnip cultivars in the USA but the acceptance of these cultivars has been poor. However, considering the higher level of heterosis for root yield, and availability of sporophytic system of self- incompatibility, it is suggested that hybrid cultivars of turnip should be developed following the procedures as outlined in case of cabbage.
7. Varietal Descriptors of Turnip:
As described by George (1999), these are as follows:
Diploid or tetraploid
Length: short-medium or long
Width: narrow, medium or wide
3. First leaf:
Hairiness on margin: very sparse, sparse, medium, dense or very dense
Attitude: erect, semi-erect, medium, nearly horizontal or horizontal
Reflex-ion of top: absent or very weak, weak, medium, strong or very strong
Green colour: very pale, pale, medium, dark or very dark
Lobes: absent or present.
Number of lobes (fully developed leaf): few, few to medium, medium, medium to many or many
Incisions of blade base (cultivars with leaves without lobes only): absent or very weak, weak, medium, strong or very strong
Undulation of margin: absent or very weak, weak, medium, strong or very strong
Dentation of margin: absent or very weak, weak, medium, strong or very strong
Length (blade and petiole): short, medium or long
Width (widest point): narrow, medium or broad
Hairiness of upper side: absent or very weak, weak, medium, strong or very strong
Anthocyanin colouration: absent or very weak, weak, medium strong or very strong
Speed of formation: very slow, slow, medium, fast or very fast
Position in soil: very shallow, shallow, medium, deep or very deep
Cork layer around skin: absent or present
Chlorophyll colouration of skin at top: absent or present
Anthocyanin colouration of skin at top: absent or present
Expression of anthocyanin colouration of skin at top: reddish or bluish
Streaking of anthocyanin colouration of skin at top: absent or present
Intensity of colouration of skin at top: weak, medium or strong
Colour of skin below ground: white, yellow, red or purple
Colour of flesh: white or yellow
Intensity of yellow colour of flesh: weak, medium or strong
Anthocyanin colouration of flesh: absent or present
General shape: flat-round, elongated or tapering
Length: very short, short, medium, long or very long
Width (at widest point): narrow, medium or broad
Relative position of widest point: low, medium or high
Curvature of main axis: absent or present
Shape of crown: strongly indented, indented, level, raised or strongly raised
Shape of base: strongly indented, indented, truncate, round or pointed
Colour of petal: lemon-yellow or orange-yellow
Length of petal: short, short to medium, medium, medium to long or long
Width of petal: narrow, medium or broad
Length of stem: short to medium, medium or medium to long
Diameter of stem (about 10 cm above root neck): small to medium, medium or medium to large
Anthocyanin coloration: absent or very weak, weak, medium, strong or very strong
Length (between peduncle and beak): short, medium or long
Length of beak: short, medium or long
Length of peduncle: short, medium or long
Colour (of ripe seeds): yellow, yellow-brown, light red-brown or dark red-brown
Weight per 1000 seeds: low, low to medium, medium, medium to high or high
10. Resistance to specific pests and pathogens:
1. Breeder/foundation seed – 1600 m
2. Certified seed – 1000 m
1. Seed to seed
2. Root to seed
1. 1000 kg/ha
2. 1000 seed weight – About 3.3 g
8. Varieties of Turnip:
There are two distinct groups of turnip:
(i) Biennial or temperate or European type,
(ii) Annual, tropical or Asiatic type.
The seed of former group can be produced in the hills and that of latter in plains. Many good varieties differing in shape and colour are now available for cultivation in both the groups.
Some of the commonly grown varieties of the two groups are:
This is a temperate type and has been developed by hybridization between Japanese White and Snowball. It is an early and high yielding variety. It is particularly suitable for the areas where growing period is very short. The roots are 8-9 cm long having 9-10 cm diameter. Tops are medium not so deeply cut.
The root is smooth, pure white, fine grained with sweet and tender flesh. The leaves of ‘Pusa Chandrima’ are superior to Snowball in ascorbic acid content both in raw and cooked condition. It matures in 50-55 days. It has been released by IARI, Regional Station, Katrain.
This cultivar has been developed by hybridization between Japanese White and Golden Ball. It is earlier than Golden Ball by about a fortnight and gives 40% higher yield. Roots are flattish round, 6-7 cm long and 7-8 cm in diameter with creamy yellow, amber coloured, fine textured and mild flavoured flesh. It is superior to Golden Ball in seed yield and less susceptible to turnip malformation, a mycoplasmal disease. It has been released by IARI, Regional Station, Katrain. It matures in 65-70 days.
Purple Top White Globe:
This is most popular variety of the temperate group. The roots are nearly round with purple colour at the top and white lower half. The flesh is white, firm, crisp and mildly sweet flavoured. The top is small erect, with cut leaves. It is an introduction and recommended by IARI. Regional Station, Katrain.
The roots are perfectly globe shaped, medium sized and smooth. It has bright creamy yellow skin and pale, amber coloured flesh of fine texture and flavour. The tops are small, erect with deeply cut leaves. It is very shy seeder are highly susceptible to turnip malformation. It takes about 65-70 days from sowing to root formation. It has been recommended by IARI, Regional Station, Katrain.
It takes about 60-65 days from sowing to root formation. The roots are globe shaped with pure white skin. Flesh is crisp, pure white and mildly sweet flavoured. This is also an introduction and has been replaced by Pusa Chandrima.
This variety has been developed from a cross between tropical type (Local Red Round) and a temperate type (Golden Ball) and was released in early sixties. It has all the good qualities of both the groups. The skin is red and the flesh is creamy yellow and it has excellent flavour and taste. It has a shorter leaf top and produces seed in the plains. The best time of its sowing is September and its yield potential is 250-300 q/ha.
This variety was developed by selection from an indigenous collection from Punjab and was released by IARI, New Delhi, in 1976. Roots are pure white, medium large, round and slightly flattish in shape. The flesh is white, soft textured, fine grained and mildly pungent. In the northern plains it can be sown from August to September. It takes 40-50 days to attain harvest maturity and yields 200-300 q/ha.
Early Milan Red Top:
This is an extra early and high yielding cultivar reaching maturity in 45 days. The roots are deep flat with purplish red top and white underneath. The flesh is pure-white, well grained, crisp and mildly pungent. The tops are very small with 4-6 sessile leaves.