New ornamental cultivars must display horticultural superiority when grown in containers or in the field. The objectives of this study were to determine whether container or field is most appropriate for initial selection of ornamental traits in a Vitex breeding program by determining whether quantitative traits of breeding interest were expressed similarly in the two environments and by determining trait correlations in each environment. Segregating populations of Vitex and their parents were cloned and grown in containers and in the field. Ornamentally significant traits evaluated included first flower date, last flower date, flowering period, total weeks of flowering, inflorescence number, inflorescence length, flower rating, plant height, plant width, and Cercospora leaf spot resistance. Overall, field-grown plants were taller and wider than plants grown in containers. Field-grown plants also had a later first flowering date, longer flowering period, greater total weeks flowering, longer inflorescence length, larger inflorescence number, and more flowers on the inflorescence. Significant genotype × environment interactions were found for height and width measurements taken 19 and 33 weeks after planting, first flower date, total weeks in flower, inflorescence number, flower rating, and Cercospora rating. Most trait correlations were either non-significant or so low so that selection of these traits would be independent of other traits. High correlations were present in both environments between height measurements taken at 19 weeks and 33 weeks after planting. High correlation in the field and moderate correlation in containers were found between width measurements taken 19 and 33 weeks after planting. Correlation was high between flowering period and first flower date in both the field and container. Correlation between last flower date and flowering period was high in containers and moderate in the field. High correlation was present in both environments between flowering period and total weeks of flowering. Containers were determined to be best for initial selection for most traits having significant genotype × environment effects.
Amanda J. Hershberger, David A. Knauft, and Carol D. Robacker
Ryan N. Contreras, John M. Ruter, and David A. Knauft
American beautyberry (Callicarpa americana) is a deciduous shrub native to the southeast United States and is grown primarily for its metallic-purple fruit that develop in the fall. There are also pink- and white-fruiting and variegated forms but these traits are rare in nature and there is no information available regarding their inheritance. Also, there is confusion regarding self-compatibility and the presence of apomixis in Callicarpa L. Crosses were performed to investigate the genetics of fruit color, self-compatibility, and apomixis in american beautyberry. Test crosses between C. americana (CA) and C. americana ‘Lactea’ (CAL) suggested that white fruit is recessive to purple. White fruit appears to be controlled by a single recessive gene for which we propose the name white fruit and the gene symbol wft. Although there were only a limited number of progeny grown, crosses between CA and ‘Welch’s Pink’ suggest that purple is dominant to pink. Test crosses between CAL and ‘Welch’s Pink’ are needed to draw conclusions; however, we propose that purple, pink, and white fruit are controlled by an allelic series for which we suggest the gene symbols Wft > wft p > wft. Segregation ratios suggested that all progeny in the study developed through sexual hybridization. All genotypes used in the current study were self-compatible.
Heidi C. Wernett, Thomas J. Sheehan, Gary J. Wilfret, Francis J. Marousky, Paul M. Lyrene, and David A. Knauft
A broad source of Gerbera × hybrida Hort. germplasm was evaluated for vase life. Senescence mode, i.e., bending or folding of stems or wilting of ligulae was also recorded for flowers evaluated. Intensive selection was practiced to improve vase life. About 10% of the plants from a sample population were selected for having flowers with high vase life. Progeny means for vase life resulting from a topcross between these plants and `Appleblossom' were used to select five plants (about 1.5% of the sample population) whose flowers had high vase life. A diallel cross using these five plants as parents resulted in a progeny population with an increase in mean vase life of 3.4 days compared to mean vase life for the initial sample population. Increases in vase life means for days to bending, folding, and wilting were 0.3, 3.5, and 1.2 days, respectively. Plants with flowers which senesced due to wilting had the longest mean vase life before and after breeding. Changes in proportion of senescence modes were observed; bending decreased, folding and wilting increased. Frequencies of bending, folding, and wilting were compared to vase life means for 10 progenies. Proportion of bending generally decreased as vase life increased.