PRIMOCANE BLACKBERRY: ANOTHER DIMENSION IN BREEDING AND SELECTION OF NEW CULTIVARS FOR COMMERCIAL MARKETS

The objective of this paper is to highlight the Primocane blackberry breeding program at Hargreaves Plants, which has multi-site trialling of selections and extensive flavour analysis, in an attempt to provide cultivars with better flavour for the growers and consumers.
Traditional blackberry Rubus subgenus Rubus breeding programmes produce progeny which are crossed and selected in one environment in the first instance. Trialling selected genotypes in grower sites and in small replicated plots follows, providing further information to aid final selection for cultivar release. For the past six years, a joint breeding programme between the University of Arkansas and Hargreaves Plants has provided a new dimension in breeding and selection of primocane blackberries for Europe and the UK, with trial sites in Spain, Mexico, and UK, comparing genotype x environment interaction. The emphases are on fruit flavour and quality, growth habit, and yield for commercial growers, as well as heat and cold tolerances, as appropriate. Further agronomy trials are ongoing to find optimal planting density, pruning techniques required for the best yields, and seasonality of selected seedlings. Fruit quality tests including shelf-life to examine firmness, sweetness and acidity, will be repeated, but in addition, flavour volatiles, °Brix and titratable acidity will be measured. This will enable development of a complex picture of the organoleptic profile. The work on selected volatiles, mainly esters, aldehydes and alcohols, will provide key information about the complex flavour in the Arkansas cultivars. As a result of this work, a better understanding of fruit flavour in blackberries will mean new milder, sweeter cultivars adapted for various climates will be available for growers and consumers.