SUCCESSFUL PRODUCTION OF HYBRID PAPAYA IN MALAYSIA

Papaya cultivars in Malaysia before the 1980s were generally non-descript, open-pollinated cultivars developed through farmers’ selections. In 1987, the Malaysian Agricultural Research and Development Institute (MARDI) released the ‘Eksotika’, a petite fruited self-pollinating pureline with strong ‘Solo’ genetic background. At that time, many researchers thought that pureline homozygous cultivars were the accepted norms in their breeding programmes. This thought was strengthened by the belief that papayas do not suffer inbreeding depression upon selfing and hence hybridization between inbred lines was unlikely to bring about heterosis (hybrid vigour). Indeed, the popular cultivars in that era were from the self-pollinating gynodioecious cultivars from the ‘Solo’ family (‘Sunrise’, ‘Kapoho’ and ‘Waimanalo’) and the open pollinated cultivars from gynodioecious or dioecious sources. F₁ papaya hybrids were not actively pursued, although globally, the seed industry for horticultural and food crops was moving rapidly towards using F1 hybrids.