B.L. Topp, D.M. Russell
The Japanese plum (Prunus salicina and hybrids) breeding programme at the GBHRS aims to produce a range of plum varieties with particular emphasis on early maturity, high fruit quality and adaptation to a marginally temperate, summer rainfall environment. Seedling production and evaluation has been improved by the use of nuclear bee hives for controlled pollinations, embryo culture of seeds from early parents and high density plantings of up to 24 000 trees per hectare. Earliness, fruit size and bacterial spot resistance are the main criteria for selection of parents.

The first crosses were made in 1967 and combined the locally adapted, early variety Wilson with other similar cultivars. Wilson has provided a source of earliness, attractive skin colour, resistance to bacterial spot but also small fruit size. The resulting progeny were very early but too small. The second group of crosses combined Wilson with mid season, large fruited parents such as Donsworth, Narrabeen, Burbank, Salad and Mariposa. This resulted in several selections ripening from early December to early January with good fruit size for their maturity time. Second generation (F2) populations have been produced from 1983 to 1987 by combining the two F1 populations and using selected overseas introductions. The third generation will be produced commencing in 1988 by intercrossing the superior F2 selections in a polycross breeding system. The F2 populations fruited for the first time in 1986 and 1987 and have showed a marked improvement in earliness combined with fruit size.

Topp, B.L. and Russell, D.M. (1989). BREEDING EARLY RIPENING JAPANESE PLUMS. Acta Hortic. 240, 27-30
DOI: 10.17660/ActaHortic.1989.240.2

Acta Horticulturae