Characterization of Abelia taxa for interspecific hybridization
Scheiber, Sloane Michele
MetadataShow full item record
Stigmatic receptivity, intra- and interspecific crossability, seed germination, ovule culture techniques, inheritance of foliage variegation, and cold hardiness were evaluated to characterize Abelia taxa for interspecific hybridization. Abelia chinensis and A. ×grandiflora ‘Francis Mason’ were evaluated for stigmatic receptivity. Receptivity of both taxa was highest on the day of anthesis, but stigmas remained receptive throughout the pollination period. Fourteen Abelia taxa were assessed for intra- and interspecific crossability. Interspecific hybrids varied in percent seed set dependent on the parentage. Low seed set among intraspecific crosses may be attributed to the presence of a selfincompatibility system. Although seed was derived from intra- and interspecific crosses, germination rates were low and pericarp removal, gibberellic acid treatments, and stratification were tested as a means of increasing germination percentages and rates of A. ×grandiflora. Stratified seeds with attached pericarps had the highest germination percentage, 63%; though not significantly different than the other treatments. Despite more uniform germination, pericarp removal, GA3 immersion, and stratification are of no practical benefit due to either reduced germination percentages or the time necessary for stratification. Seeds from interspecific hybridization between ‘Francis Mason’ and A. schumannii failed to germinate prompting development of an ovule culture technique. Ovules were cultured 5 weeks after pollination on Woody Plant Medium containing no growth regulator resulted in the highest ovule recovery rates, 85%, and seedling survival rates, 65%. Segregation ratios from reciprocal crosses between A. chinensis, a greenleafed species, and ‘Francis Mason’, a yellow cultivar of A. ×grandiflora, and backcross progeny could not be conclusively fit to a model. The best fit was obtained using a 2- gene model of duplicate recessive epistasis with yellow dominant to green foliage. Twelve taxa were evaluated using laboratory procedures to determine maximum stem and leaf cold hardiness and to evaluate timing of acclimation and deacclimation. ‘Edward Goucher’ and ‘Confetti’ had the least hardy stems and leaves, respectively. ‘John Creech’ ranked in the hardiest group of taxa for both stems and leaves on the majority of test dates and would make a logical choice for incorporation into a breeding program.