Heritability of Fruit Splitting Tendency in Blueberry

Rain-induced fruit splitting is a common problem in many blueberry production regions.  Following a 2011 survey of British Columbia blueberry growers in which reduced splitting tendency ranked highly as an industry need, this trait has become one of the objectives of the BC blueberry breeding program.  While laboratory methods have been developed to screen blueberry genotypes for splitting tendency and large differences have been observed between genotypes, little is known about the inheritance or heritability of this trait.  As part of a multi-year study to identify sources of variation and track response to selection in the breeding program, we used a laboratory assay to determine the splitting tendencies of 2618 seedlings in 2014 from 51 full-sib families resulting from crosses between 16 parents. The mean proportion of split fruit in seedling families ranged from 2% to 27%, while the mean proportion of split fruit in their parents ranged from 0% to 46%.  Using mid-parent regression, we obtained a moderately-high preliminary heritability estimate for fruit splitting tendency (h² = 0.62).  Future work will focus on determining combining ability and breeding values of parents, determining splitting tendency in broader germplasm, and studying response to selection over multiple breeding cycles.