Double-cross: a suitable method to improve Malaysian Eksotikas

A double-cross method was applied to improve yield and fruit qualities, as well as storage life of Malaysian 'Eksotika' papayas. A non-indigenous papaya, 'PR217' was chosen as one of the parents to provide a wider genetic base. It has very small fruits (about 200 g per fruit), is a dwarf (0.5 m plant height at the first flowering stage) and has longer storage life compared to 'Eksotika'. Besides providing a wide genetic base, a double-cross method can enhance expression of heterosis. Two double-cross hybrids, i.e., [Eksotika II × (Line 19 × PR217)] and [(Sekaki × Line 20) × (Line 19 × PR217)] were generated and evaluated together with 'Eksotika', 'Eksotika II' and 'Line 19'. The double cross [Eksotika II × (Line 19 × PR217)] shows improved overall desirable traits compared to the other four genotypes. It has higher yield (34 kg 
plant^-1 year^-1), T.S.S. (13.6%) and longer shelf-life (6.3 days from Index 2 to 5 NDASH eating stage) compared to 'Eksotika', 30 kg plant^-1 year^-1, TSS = 11.6% and 4.5 days, respectively. It also has better fruit appearance with minimal freckles on the skin compared to 'Eksotika'.