Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: Kelly M. Thomas x
Clear All Modify Search

Rudbeckia subtomentosa ‘Henry Eilers’ is an adaptable and popular garden plant; however, reduction in height and increased novelty in flower color would be desirable. The effect of gamma radiation dose on in vitro survival and development, and ex vitro fertility, phenology, and morphology of tetraploid Rudbeckia subtomentosa ‘Henry Eilers’ was investigated. In vitro embryogenic callus was treated with gamma radiation (0, 5, 10, 20, or 40 Gy). Rooted microshoots were established ex vitro and evaluated for morphology (plant height, number of flowers, diameter of the terminal flowers, diameter of the secondary flowers, number of stems, number of nodes, and internode length), date of first anthesis, winter survival, and pollen fertility on mature, second-year plants. Callus survival had no response to dose 2 months after treatment; however, microshoot number was significantly reduced with increasing dose. In vitro microshoot survival continued to decline at higher doses up to 4 months after treatment. Plant height, average stem height, number of flowers, flower diameter, percent winter survival, and pollen viability were all reduced with increasing radiation dose. Date of first anthesis was also delayed with increased radiation dose. Several off phenotypes were recorded including increased apical splitting of the ray florets in several plants. Gamma radiation was somewhat effective for reducing the height of R. subtomentosa ‘Henry Eilers,’ but flower morphology, flower number, and plant overwintering survival were often negatively affected with increasing radiation dose. Treating callus with low levels of gamma radiation (5–10 Gy) resulted in relatively high in vitro and field survival while inducing a range of other mutations that could be selected.

Free access

Rudbeckia spp. are adaptable and valuable ornamental wildflowers. Development of new varieties of Rudbeckia spp., with improved commercial characteristics, would be highly desirable. Interspecific hybridization and induced polyploidy may be avenues for improvement within the genus. The objective of this study was to evaluate fertility, morphology, phenology of flowering, and perennialness (overwintering survival) for lines of diploid and induced allotetraploids of R. subtomentosa × hirta and diploid and autotetraploids of R. subtomentosa ‘Henry Eilers’. Polyploid lines were developed and propagated in vitro and then grown ex vitro in a randomized complete block design with 12 replications. Compared with their diploid counterparts, autotetraploid lines of R. subtomentosa ‘Henry Eilers’ had similar internode lengths, plant heights, number of stems, flowering times (date at first anthesis), and fall and spring survival (100%); reduced number of inflorescences and male and female fertility; and increased inflorescence diameters. Compared with their diploid counterparts, allotetraploids of R. subtomentosa × hirta had similar internode lengths, reduced number of inflorescences, delayed flowering times, and increased pollen staining. Allotetraploids had limited male and female fertility compared with no detectable fertility in their diploid counterparts. Plant height and number of stems either decreased or showed no change with induced allotetraploidy. Spring survival of diploid hybrid genotypes ranged from 0% to 82% and was not improved in the allotetraploid hybrids. For a given genotype, some polyploidy lines varied significantly in certain morphological traits (e.g., plant height) indicating somaclonal variation may have developed in vitro or there were variable genomic or epigenetic changes associated with induced polyploidy.

Free access

Trees in the Theaceae tribe Gordonieae are valuable nursery crops, but some of these taxa are known to be highly susceptible to root rot caused by Phytophthora cinnamomi Rands. The objective of this study was to evaluate a collection of Gordonieae taxa for resistance to this pathogen. These taxa included Franklinia alatamaha Bart. Ex Marshall, Gordonia lasianthus (L.) Ellis, Schima wallichii Choisy, S. khasiana Dyer, ×Schimlinia floribunda Ranney & Fantz, and ×Gordlinia grandiflora Ranney & Fantz. Abies fraseri (Pursh) Poir. was also included in the study as a positive control. Container-grown trees were inoculated with three isolates of P. cinnamomi and symptoms were rated over an 84-day period during the summer of 2008. Disease symptom ratings from 1 (healthy) to 4 (dead) were collected twice weekly and area under the disease progress curve (AUDPC) values were calculated. None of the S. khasiana or S. wallichii exhibited any root rot symptoms or mortality, whereas the remaining species showed symptoms of infection at varying levels over time. Symptoms in F. alatamaha and A. fraseri were apparent before other taxa, and mortality for both species reached 100% by the end of the experiment. Comparison of AUDPC values indicated that F. alatamaha was the most susceptible followed by A. fraseri. There was no significant difference in AUDPC among the more resistant taxa, including G. lasianthus, both Schima species, and the intergeneric hybrids. Values for AUDPC in the hybrid taxa were similar to their more resistant parental genus, indicating that resistance to P. cinnamomi is a partially dominant trait in these plants. These results further suggest the potential to breed improved hybrids of Gordonieae trees with substantial resistance to P. cinnamomi.

Free access

Ornamental rhizoma peanut (Arachis glabrata Benth.; ORP) is a low-maintenance groundcover for use in urban and residential landscapes. Despite its availability since 2002, consumer insights on ORP have never been assessed. Online surveys are readily accepted by academic researchers as a valuable research tool. An online survey was distributed to 5820 Floridians with the objective to assess the use and perceptions of ORP by consumers. A total of 907 survey responses were received. Most respondents identified themselves as home gardeners (89%), white (93%), female (75%), and over age 65 (60%). Out of several turfgrass alternative benefits, respondents most valued reducing herbicide/pesticide and fertilizer/water usage and preventing weed establishment (χ2 = 204, df = 6, P < 0.001). The ORP selection purchased by respondents was predominately unknown. Most preferred ORP to flower heavily and frequently and maintain a canopy height below 20 cm in the landscape with infrequent mowing. Survey data show there is a potentially large consumer demand for ORP in Florida, but product availability, branding, and consumer access and engagement with information sources require additional focus in the coming years.

Open Access

The IdeaMap® software suite and the concept of Mind Genomics® were used to analyze which features of a flower product are influential to consumer perception. By presenting online human subjects with combinations of elements that describe a flower product, a database was created to define how individuals perceive distinct components of an overall flower product. This study was conducted with two separate groups of participants, the first provided by a panelist fielding house and the second administered to an undergraduate introduction to plants and gardening class. The fielding house participants represented various demographic groups throughout the United States and the majority was 40 years of age and older. The undergraduate class participants consisted primarily of white, female students between the ages of 18 and 24 years. Each study participant was exposed to a permutation of flower-based elements derived from six categories: flower color, flower shape, consumer health and wellness, flower fragrance, flower purchase location, and flower use. The results of the two studies illustrated which elements of each flower category appealed to different demographics of the population and were used to identify segments of the population that possessed similar mindsets toward elements of interest and disinterest in regard to a flower product. In both the fielding house and student IdeaMap® studies, the highest and lowest interest values were for elements from the flower fragrance category, indicating that floral fragrance is an important aspect of flowers with respect to current and future consumer satisfaction. Three distinct segments were identified in each study with the segments being primarily concerned with elements involving olfaction, visual, and other attributes of a flower product.

Free access