Papaya Breeding Program in the Department of Agriculture

The Department of Agriculture (DOA), Ministry of Agriculture and Cooperatives, Thailand has conducted papaya breeding since 1984. These programs were divided into two types, conventional breeding and genetic engineering. Conventional breeding included selection and crossing of papayas. Seeds were collected from various sources, planted and selected for desired characteristics. They were self-pollinated to increase the purity of the lines. The DOA recognized and registered ‘Khaek Dam Si Sa Ket’ cultivar in 1994. With regard to cross breeding, ‘Khaek Dam’ cultivar was crossed with ‘Coimbatore No.2’ (‘Co2’) cultivar. The cross bred seeds were selected from the F1 hybrid papaya. The DOA named this fruit ‘Phichit’ and it became a registered cultivar in 1997. There is also a cross between the ‘Khaek Dam’ and the ‘Florida Tolerant’. From this program, new cultivars, ‘Khaek Dam Tha Phra’ and ‘Khon Kaen 80’ were selected based on good agricultural traits and then the ‘Khaek Dam Tha Phra’ was registered in 1997. On the other hand, the genetic engineering improvement under the DOA was in collaboration with Cornell University. The coat protein gene (CP gene) of Papaya ringspot virus (PRSV) was transferred into Thai papaya, ‘Khaek Dam’ and ‘Khaek Nuan’ cultivars. Potential resistant cultivars were selected for the R0 PRSV of the resistant papaya, including one ‘Khaek Dam’ and four ‘Khaek Nuan’ cultivars. Currently, one ‘Khaek Dam’ and two ‘Khaek Nuan’ cultivars are selected for the R3 PRSV resistant papaya.