Genetic control of traits in Japanese quince (Chaenomeles japonica)

Phenotypic variation and patterns of inheritance of several plant and fruit traits were studied in Japanese quince [Chaenomeles japonica (Thunb.) Lindl.], Maloidea (Rosaceae). Japanese quince is a minor fruit crop in Latvia and Lithuania, and is presently being also developed in Sweden for production of juice, aroma and fruit fibre. To study the genetic control of traits, plants with contrasting characters were selected in seed-propagated commercial orchards, and crossed. Fourteen hybrid families were obtained, for which five plant vegetative traits (thorniness, branching, density, plant habit and height), seven fruit yield and morphological traits (annual yield, accumulated yield, fruit number, fruit weight, fruit flesh, number of locules and seed weight), and five fruit biochemistry traits (antioxidant activity, soluble solids, galacturonic acid, malic acid and succinic acid) were evaluated. General and specific combining abilities were estimated and correlation coefficients were calculated among traits. Thorniness seems to be controlled primarily by a single locus. All other traits studied appear to be governed primarily by additive genes, as judged from general combining ability estimates. Significant specific combining ability (SCA) was detected for yield, plant height and some fruit biochemistry traits. However, the relative contribution of SCA to the overall genetic variance was generally low. An efficient breeding strategy for Japanese quince could therefore be based on recurrent selection.