Breeding and selecting new varieties and rootstocks of custard apple (Annona spp. Hybrids) in subtropical Australia

Considerable progress has been made in selecting new types and gaining an understanding of the inheritance of desirable traits in custard apple. Inter-varietal crosses were made between the best selections of custard apple and the main commercial cultivars such as ‘KJ Pinks’, ‘Maroochy Gold’, ‘Palethorpe’ and ‘Maroochy Yellow’. Inter-specific crosses were made between four different species, Annona cherimola (cherimoya), A. squamosa (sugar apple), A. reticulata (Bullock’s Heart) and A. diversifolia (Ilama). Some 15 000 breeding lines were field planted since 1998. Alternative breeding approaches were also evaluated. Fifteen advanced selections from the breeding program are being trialed at six evaluation sites throughout Queensland and northern NSW. The program has successfully developed hybrids with red skin colour and pink internal flesh. Red skin colour was found to be controlled by either a single or double recessive genes. Rootstocks with potential dwarfing characteristics such as shortened internodes and short, bushy stature have also been selected out of seedling progeny. These selections are in the process of being clonally propagated for future field-testing with a range of new scion varieties.