Hybrid performance and heterosis in strawberry (Fragaria × ananassa Duchesne), regarding acidity, soluble solids and dry matter content in fruits

A top-cross-mating design among 29 S4 inbred lines and tester (cultivar ‘Dukat’) was carried out to study their breeding value in terms of general combining ability (GCA). The objectives of this study were to evaluate the acidity, soluble solids and dry matter contents in fruits of progeny F1 in comparison with S4 inbred lines as well as the cultivars (S0); identify strawberry genotypes with high value of GCA for use in cultivar development; and determine mid-parent heterosis regarding S4 inbred lines and cultivated strawberry. The 2-year observations showed statistically significant differences between tested genotypes in terms of the studied traits. The highest breeding value based on GCA was estimated for Chandler 123-5 for soluble solids and dry matter content, and Kent 7-6 for acidity. Estimated mid-parent heterosis had positive and negative values. The highest heterosis in terms of extract and dry matter content (26.71% and 17.50%, respectively) occurred in the offspring Chandler 123-5 × ‘Dukat’, but as regards acidity in hybrid Chandler 123-22 with cv. ‘Dukat’. The study of genetic divergence by dendrograms may help to identify parents suitable for obtaining hybrids with higher heterosis effects.