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Bottlebrush (Callistemon vinimalis) is a widely propagated and cultivated ornamental large shrub with large red bottlebrush-like flowers. Traditional clonal propagation using stem cuttings may be replaced with tissue cultured liners. In this study, we established a container-grown field experiment of bottlebrush ‘Little John’ using liners propagated from both rooted stem cuttings and tissue culture. Growth index was recorded by propagation method periodically through the 34-week period, and both fresh and dry weights of roots and shoots recorded at experiment’s end. Final growth index of plants grown from tissue cultured liners were significantly greater than growth index of plants started from rooted stem cuttings. Both fresh and dry root weight means were significantly greater in plants propagated by tissue culture. Further testing of containerized bottlebrush production, through the flowering stage, will better determine whether tissue-cultured liners accelerate production time vs. liners from stem cuttings.
Variation in floral characteristics and growth habits within the native range of the North American wildflower Ratibida columnifera (Nutt.) Wooton & Standl. suggest potential for breeding and selection efforts to develop improved cultivars for commercial and residential landscapes. Toward that end, experiments in vegetative propagation were performed to enable perpetuation of unique germplasm. Stem development stage, applications of auxin, genotypic variation, and the effects of bottom heat applications were assessed to determine impacts on rooting percentages and adventitious root system quality measures. Younger apical stem sections rooted more readily and produced better quality root systems than more lignified basal stem cuttings. Optimal rooting percentages and rooted cutting quality ranged from 0.10% to 0.30% IBA (indole-3-butyric acid) quick dips, with 0.30% being optimal for most genotypes. Application of 26 °C bottom heat improved rooting ability in both cool and warm seasons compared with ambient and bottom heat of 32 °C. Bottom heat of 32 °C improved most rooting measures over ambient during the cool season, but not during the warm season. The degree of improvement in adventitious rooting associated with various developmental stage, auxin quick dips, and bottom heating varied among accessions of R. columnifera, suggesting that adventitious rooting characteristics should be evaluated as a selection criterion for cultivar development within this species.
Variation in floral characteristics and growth habits within the native range of the North American wildflower Ratibida columnifera (Nutt.) Wooton & Standl. suggests potential for breeding and selection efforts to develop improved cultivars for commercial and residential landscapes. Experiments in seed propagation were performed to enable perpetuation of unique germplasms. Overnight hydration, storage condition variations, stratification and scarification, and seed maturation effects were assessed to determine impacts on viability and percent germination. Overnight hydration had no impact on percent germination. Germplasm had a significant effect on germination for all remaining experiments. Seed maintained viability at the same rate through 18 months, when slight reductions were noted. Cold storage at 3 °C had no effect on viability or percent germination of dry seed compared with storage at 23 °C. All three germplasms exhibited increased percent germination with some stratification period, and declined significantly in percent germination with all acid scarification treatments. Experiments indicated that most germplasms benefit from between 30 to 60 days of cold, moist stratification. There was a significant interaction effect among germplasms, location on the inflorescences, and maturity stages for R. columnifera. Data suggest that seed should be harvested as close as possible to when natural dispersal would occur for optimum germination. The degree of improvement in viability and percent germination associated with harvesting at various developmental stages, seed pretreatments, and storage conditions suggests that to achieve germination success, pretreatments should be used for propagation of seed from mature inflorescences and that variation can be expected within different genotypes of this species.
Conjoint analysis can be used to simultaneously investigate consumer preferences on multiple attributes and levels. Our objective was to gain insight regarding consumer preferences for attributes and levels attributed to Ratibida columnifera, a wildflower of potential commercial interest. A ratings-based conjoint analysis using petal color (bicolor, marble, red, yellow), petal shape (circular, oval, notched, lobed), petal number (less than 10, more than 10), and price ($10.00, $15.00, $20.00) was conducted to elucidate part-worth utility from data from 1000 subjects recruited using Amazon Mechanical Turk (MTurk), a crowdsourcing marketplace. Subjects were then clustered according to their conjoint utility scores. In addition to the conjoint analysis, a principal component analysis was performed based on native plant knowledge of the respondent. Conjoint results revealed that petal color was the most important attribute in decision making, followed by price, petal shape, and petal number. Utility values revealed preference for bicolor petals, followed by red, yellow, and marbled color petals. Preference for price went from least expensive to most expensive. Circular petals were favored over oval, notched, and lobed. Subjects also preferred to have 10 petals or more, vs. less than 10 petals. Cluster analysis yielded three consumer segments, which differed in their utility values. These clusters differed in both demographics and R. columnifera preferences. Overall, consumers preferred R. columnifera with partial (bicolor) or complete red coloration over other options, lower prices, more petals, and entire circular or oval petals.