Interspecific hybridization of Fragaria moschata with two diploid species, F-nubicola and is F-viridis

The crosses Fragaria moschata x F. nubicola, F. moschata x F. viridis, and their reciprocal combinations were done to create tetraploids for eventual introgression into octoploid cultivars of Fragaria x ananassa via the synthetic octoploid system. The combination F. nubicola x F. moschata averaged 3.3 healthy plants/pollination, which was 2.3 times higher than the next best combination, F. moschata x F. viridis. Fragaria viridis x F. moschata crosses averaged only 0.1 healthy plants/pollination and no plants were obtained from F. moschata x F. nubicola hybridizations. The success of the F. nubicola x F. moschata crosses in this study indicated that embryo/endosperm ratios were not as important a factor in producing hybrids with F. moschata x diploids species, as previously suggested. Although 90% of pollinated flowers set fruit with an average of 19 seeds/pollination only 15% of the seeds contained healthy, white embryos and only 38% of these developed into healthy seedlings. The remaining 62% of embryos lacked pigment, had short hypocotyls or arrested development after slight expansion out of the seed coat. Only 39% of the crosses resulted in viable progenies. After one year, 27% of these hybrids bloomed and 71% of the blooming hybrids were tetraploids. All six diploid and six of the seven hexaploid accessions were successfully incorporated into 89 hybrids.