Breeding objective for strawberry in subtropical southeast Queensland

An 'aggregate economic' value (H), which is a combination of genetic control and relative economic value of traits, for all traits in the breeding objective was developed to aid in multitrait selection of strawberry cultivars in the subtropical southeast Queensland program. A profitability index for 12 traits was calculated from the effect of unit changes in each trait on changes in production costs and profitability. The index was applied to the breeding values of 3008 genotypes to produce estimates of H. H was validated by its high correlation (R-2=0.77) with year of selection (1945-1998) for commercial cultivars. H values for 3008 genotypes ranged from -0.36 to +0.28, when the zero value was set to the value of the cultivar 'Festival', which is the main cultivar grown in southeast Queensland. Modelling indicated that the gross margins were highly linearly related (R-2>0.98) to H values where the genotype occupied less than 50% of total area planted in the industry, but this relationship became quadratic when the genotype occupied higher percentages of the total area planted to strawberries, and variation in gross margin increased as H values increased. H is efficient in identifying economically superior genotypes, but, when deploying new genotypes with high H, impacts on farm gross margin due to high adoption rates should also be considered.