Breeding of papaya

Major Breeding aspects of Papaya

1. Breeding of Papaya Davinder Handa M.Sc Agriculture (Fruit Science)

2. Taxonomic classification Botanical name : Carica papaya Family : Caricaceae Chromosome no. : 2n=2X=18 Origin : Mexico

3. Introduction Papaya has 6 genera and 35 species . It is naturally a dioecious plant , but gynodioecious cultivars have been developed in papaya through breeding. The leaves are palm like with long talks. Fruit : Fleshy Berry . Numerous round wrinkled black seeds.

4. Centre of Diversity Papaya is native to Tropical America . The South America and Costa Rica are the micro centre of origin of papaya . It is a close relative of Carica peltata . In India , it was introduced in the early part of the 16 th century from Philippines through Malaysia . It was widely spread in different parts of the country particularly tropical and sub-tropical zones. India is the largest producer of papaya in the world. It is also cultivated in Brazil, Mexico, Australia, Hawaii, Malaysia, Taiwan , Peru, Florida, Gold Coast, South Africa and Bangladesh . In India it is widely cultivated in Uttar Pradesh, Bihar, Karnataka, Jharkhand and Madhya Pradesh.

5. Germplasm Resources The family Caricaceae consist of 6 genera and 35 species . Carica and Vasconcellea are the important generas . The genus Carica has only one species , Carica papaya the cultivated species. Vasconcellea contain 21 species , which are considered as the wild relatives of papaya . Presently , germplasm is being maintained at TNAU, Coimbatore , IIHR, Bangalore, IARI Regional Station, Pusa, Bihar, CHES (Central Horticultural Experiment Station), Ranchi, CHES , Bhubaneshwar and CISH, Lucknow for further characterization and evaluation.

6. Carica cauliflora

7. Carica candicans

8. Objectives To develop dwarf and early bearing varieties. To evolve varieties with high yield and good quality fruits. To develop varieties with low cavity index and more pulp thickness . To breed varieties having good keeping quality and suitable for export . To develop varieties resistant to biotic and abiotic stresses (virus, frost, water logging etc).

9. Floral biology and pollination Dioecious papaya produces male and female trees separately on different plants in the ratio of 1:1. Female and male flowers develop within 32 and 42 days respectively after bud initiation . The period from bud initiation to anthesis is shorter for male than female flower bud.

10. Papaya Flowers

11. Sex forms There are two major sex forms in papaya 1. Dioecious : male and female trees segregate in the ratio of 1:0. Sibmating is done for maintaining of purity. 2. Gynodioecious : Female and andromonoecious (female + bisexual flowers in a single tree) trees segregated in the ratio of 1:2. Selfing of bisexual flowers is done for obtained pure seeds.

12. Fig. : Papaya male plant with fruits

13. Fig. : Papaya female plant with fruits

14. Fig. : Papaya hermaphrodite plant with fruits

15. Breeding methods and achievements Inbreeding and selection In dioecious lines , suitable male plants are selected from the same progeny which have resemblance to female plants in vegetative characters , such as stem and leaf colour, stem thickness and height at flowering etc. Progenies raised from S1 inbreds are screened and desired male and female plants are selected for further sibmating i.e., crossing between the female plant and male plant of the same cultivar. The process is to be continued for 7-8 generations to achieve uniformity for a group of characters. In this method, the progeny will have male and female in equal proportion. Many dioecious cultivars have been bred by this method.

16. Achievements Development of cultivar with high papain content was started at TNAU , Agricultural College and Research Institute, Coimbatore. As a result of intensive breeding programme, four cultivars i.e., CO1, CO2, CO5 and CO6 were developed through inbred selection which are dioeicous at Coimbatore .

17. Recently during 2011, CO 8 papaya was developed in the dioecious group through sib-mating of CO 2 variety , which is a red fleshed variety and this variety is unique for the red pulp colour which is not exist in any of the dioecious papaya varieties developed. As a result of inbreeding and selection for 8 generations during 1966-1982 , uniform lines of Pusa Delicious, Pusa Majesty, Pusa Giant and Pusa Dwarf with desirable attributes were developed.

18. Important cultivars of papaya developed through selection are as under

19. Hybridization A few hybrid varieties have been developed by the intervarietal or intergeneric hybridization . But still there is great scope for development of superior cultivars with better quality and yield. At TNAU, Coimbatore three varieties have been developed viz. CO3 (CO2 x Sunrise Solo), CO4 (CO1 x Washington) and CO7 (CP.75 x Coorg Honey Dew). At IIHR Bangalore , two hybrids IIHR-39 named as Surya (Sun Rise Solo x Pink Flesh Sweet), and IIHR-54 (Waimanalo x Pink Flesh Sweet) were developed ( Dinesh and Yadav 1998), Hybrid HPSC-3 (Tripura local x Honey dew) was developed by the ICAR Research Complex Tripura (Singh and Sharma, 1996).

20. Mutation breeding Ram and Majumder (1981) developed a dwarf mutant line by treating papaya seed with 15K gamma rays . Initially, 3 dwarf plants were isolated from M2 population. Repeated sibmating among the dwarf plants helped in establishing a homozygous dwarf line Pusa Nanha .

21. Different varities of papaya

22. Questions 1. Papaya known as. Ans : Wholesome fruit 2 . Name a transgenic papaya Ans : U.H Rainbow 3 . Name two papaya varieties suitable for papain extraction as well as table purpose are Ans : CO2 and CO5 4. Vasconcellea cauliflora is resistant to Ans : Papaya Ring Spot Virus (PRSV) . 5. . Pusa Nanha is developed through. Ans : Mutation breeding 6. Two major sex forms in papaya are Ans : Dioecious and Gynodioceious

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