Production Costs and Profitability for Selected Greenhouse Grown Annual Bedding Plants: Partial Enterprise Budgeting and Sensitivity Analysis

The objective of the research described in this publication was to estimate the cost of greenhouse production for selected annual bedding plants and help growers to determine how the particular crop they are growing influences profitability.

Seed Germination and Seedling Growth of Four Bedding Plants in Substrate Containing Coal Bottom Ash Mixed with Coir Dust

Coal bottom ash (BA) is a by-product of coal-fired power generation and can be utilized as a growing substrate for ornamental plants. The physical and hydraulic properties of BA-mixed substrates (coir dust:BA, 10:0, 9:1, 8:2, 7:3, and 6:4, v/v) and commercial germinating media (BM2; Berger Peatmoss) were investigated, and the effects of the substrate mixtures on seed germination, seedling growth, and heavy metal concentrations (Cd and Pb) were evaluated for four common bedding plants (periwinkle (Catharanthus roseus), globe amaranth (Gomphrena globose), impatiens (Impatiens walleriana), and petunia (Petunia multiflora)). As the BA:coir dust increased, the air space rate in the substrate increased from 25.5 to 28.0%, providing the substrate with sufficient porosity. However, the container capacity and amount of easily available water decreased from 63.1 to 53.7% as BA proportions increased. In the final germination percentage and days to germination of the four bedding plants, no significant differences were detected among the substrate mixtures. Although the impatiens and petunias displayed poor growth (46–55% and 42–56% of dry weight, respectively) in the BA-mixed substrates compared to the BM2, no apparent differences in the seedling growth of periwinkles and globe amaranths were found between 7:3 (coir dust:BA) substrate and BM2. These results indicated that the BA-mixed substrates had the potential to replace the commercial germinating media. The plants grown in the BA-mixed substrates contained Cd, but it was unlikely to be derived from the BA.

Evaluation of Calcium Application Methods on Delaying Plant Wilting under Water Deficit in Bedding Plants

Floriculture crops can lose their aesthetic quality due to water deficit during postproduction. Calcium is a secondary messenger in plant stress signaling, and the treatment of calcium has been proposed to alleviate damage by various abiotic stresses. The objective of this research was to evaluate application methods of calcium to delay plant wilting under water deficiency in three species of bedding plants: viola (Viola cornuta), impatiens (Impatiens walleriana), and petunia (Petunia grandiflora). Three application methods were compared including spray, drench, and pre-drench. Calcium was applied as CaCl2 and Ca(NO3)2 at three concentrations ranging from 50 to 300 mM. The effect of calcium on shelf life was species-dependent, increasing shelf life in viola and impatiens, but not in petunia. Viola showed increased shelf life up to 154% and 400% in drench and pre-drench applications, respectively, compared to the control. In impatiens, spray and pre-drench applications delayed wilting symptoms by 53% and 200%, respectively. Comparing calcium sources, CaCl2 was the most effective as a drench, while Ca(NO3)2 pre-drench application effectively delayed wilting. There was no difference between CaCl2 and Ca(NO3)2 in spray application. These results provided the optimum application methods to delay plant witling and the potential of calcium application on enhancing water deficit tolerance in floriculture crops.

Garden post-transplant effects of pre-transplant plug cell volume and growing medium quality (as abiotic stresses) in Impatiens walleriana

Although much is known about the production of bedding plants, including Impatiens walleriana, little has been documented on their post-production performance. Thus, the aim of this work was to understand how pre-transplant crop management related to root restrictions imposed by plug cell volume and substrate quality affects the post-production performance related to biomass accumulation. To this end, we tested four plug cell volumes, as well as four growing media with significantly different physical and chemical properties, during nursery and pot culture. We also evaluated the difference between use and nonuse of synthetic cytokinin spray (benzyl aminopurine, BAP), a proven stress alleviator. Our novelty data validated the previous hypothesis and showed that plant quality and garden performance are dependent on these potential stress sources. The physiological mechanisms involved included differences in leaf area expansion (estimated mainly by relative leaf area expansion rate) and differences in CO2 fixation capacity (estimated by net assimilation rate). The sum of these responses determined significant differences in total fresh and dry weight during pot culture, which were amplified when plants were transplanted to a field bed. Spraying plants with synthetic cytokinin early during nursery allowed overriding of most root restriction abiotic stresses related to plug cell volume and growing media; therefore, synthetic cytokinin constitutes a tool to improve the yield of bedding plants (at the grower's level) and garden performance.

A protocol for fast in vitro propagation of Impatiens hawkeri cv. Sweeties Blue Star, an important ornamental-cover species

Impatiens hawkeri is among the three important bedding plants in the world. There is no efficient protocol for fast micropropagation of Impatiens hawkeri cv. Sweeties Blue Star. Single nodes were germinated on Murashige and Skoog (MS) medium supplemented with 1-naphthaleneacetic acid (NAA; 0.00, 0.10 and 0.50 mg l-1), 6-benzyladenine (BA; 0.00, 0.10, 0.50 and 1.00 mg l-1) and kinetin (KIN; 0.00, 0.10, 0.50 and 1.00 mg l-1). The shoot length was highest in medium containing 0.10 mg l-1 NAA and control. The largest number of shoots (14.06 and 14.00 per explant) was produced in media supplemented with 1.00 mg l-1 BA, 0.50 mg l-1 NAA and 1.00 mg l-1 BA, 0.10 mg l-1 NAA, respectively. The 0.10 mg l-1 NAA along with 1.00 mg l-1 BA was found to be superior for production of leaf (57.13). Maximum root length (33.80 mm) and root number (29.13) were obtained on medium supplemented with 0.10 mg l-1 NAA without BA and KIN. Plantlets were transplanted to pots filled with perlite and peat moss (in ratio of 1:1) and transferred to the greenhouse for acclimatization. Regenerated plantlets were morphologically identical with mother plants. Upon ex vitro transfer, 100% of plants survived.

EVALUATION OF SUNFLOWER GENOTYPES (HELIANTHUS ANNUUS L.) AS BEDDING PLANTS IN THE COASTAL ECOSYSTEM

The sunflower genotypes were evaluated to check their suitability as bedding plants for use in future trials to standardize their production technology in the coastal ecosystem. Fifty genotypes were evaluated which was laid out in a randomized block design replicated thrice. The experiment was conducted in the Floriculture Unit of the Department of Horticulture, Faculty of Agriculture, Annamalai University. The vegetative parameters viz., plant height, number of leaves, leaf area, foliage rating and the flowering parameters viz., days to first flowering, flower diameter, ray floret arrangement and flower rating were observed. The cultivar with an outstanding overall performance was ‘Ring of Fire’ which has glowing golden yellow and reddish brown petals forming an indistinct ring around the dark center. This cultivar was found to be suitable as bedding plant in the coastal ecosystem in terms of all the vegetative and flowering parameters

Bedding plant production and the challenge of fungal diseases

Bedding plants are a major group of ornamentals produced in greenhouses or nurseries worldwide and planted outdoors. Their economic importance has increased continuously in the last four decades in both the United States and the European Union. These plants are subject to many diseases that can negatively impact their production and cultivation. The initial steps of production strongly influence the health status of these plants and, consequently, their aesthetic appeal, which is a strong requisite for consumers. Seeds, cuttings, other forms of propagative material, along with production systems and growing media can influence the phytosanitary status of the final product. In this paper, case studies of soil-borne and foliar diseases are presented together with preventive measures to achieve innovative disease management strategies. Quarantine restrictions and eradication measures are also discussed, in consideration of the high likelihood for ornamental plants to be long-distance vectors of new pathogens and pests.

First Report of Podosphaera xanthii Causing Powdery Mildew on Zinnia elegans in Taiwan

Zinnia elegans L., known as common zinnia, is an annual flowering plant belonging to the Asteraceae family and native to North America. The plant has colorful flowers and is one of the popular ornamental bedding plants for gardening. In March 2020, powdery mildew symptoms were observed in a zinnia floral field with an incidence of >70% in Dacun Township, Changhua County, Taiwan. The symptoms were spotted on the stems, flower petals and leaves which appeared as irregular colonies and white patches on the surfaces. When disease progressed, most of the plant surfaces were covered by the white fungal colonies and became yellowish. Under microscopic examination, hyphal appressoria of the fungus were indistinct or slightly nipple-shaped. The conidiophores were unbranched, erect, straight, smooth to slightly rough, 75.0 to 200.0 × 10.0 to 15.0 µm (n=10), composed of a cylindrical, flexuous foot cell, 40.0 to 100.0 × 8.8 to 15.0 µm (n=10), and following 1 to 5 shorter cells. The conidia were ellipsoid to ovoid, 25.0 to 37.5 × 15.0 to 23.8 µm (n=60), with an average length-to-width ratio of 1.8 and contained fibrosin bodies. No chasmothecia were found. Three voucher specimens (TNM Nos. F0033680, F0033681, and F0033682) were deposited in the National Museum of Natural Science, Taichung City, Taiwan. To confirm the identification, the internal transcribed spacer (ITS) regions of the three specimens were amplified using primer pairs ITS1/PM6 and PM5/ITS4 (Shen et al. 2015) and sequenced from both ends. The resulting sequences were deposited in GenBank under Accession Nos. MT568609, MT568610, and MT568611. The sequences were identical to each other and shared a 100% identity with that of Podosphaera xanthii MUMH 338 on Z. elegans from Japan (Accession No. AB040355) (Ito and Takamatsu 2010) over a 475 bp alignment. Accordingly, the fungus was identified as P. xanthii (Castagne) U. Braun & Shishkoff (Braun and Cook 2012) based on its morphological and molecular characters. Pathogenicity was demonstrated through inoculation by gently pressing naturally infected leaves onto leaves of three healthy potted common zinnia that had been sprayed with 0.02% Tween 20. Additional three non-inoculated plants treated in the same way without inoculating the powdery mildew served as the controls. Powdery mildew colonies were observed on inoculated leaves after 10 days at room temperature, later the diseased leaves became yellowish and deteriorated. The morphological traits of the fungus on the inoculated leaves were similar to those of the first observed. In addition, the ITS sequence from a colony on the inoculated leaves was 100% identical to MT568609-MT568611, fulfilling the Koch’s postulates. All the controls remained symptomless. Z. elegans is known to be a host for different species of powdery mildew in the genus Erysiphe, Golovinomyces, and Podosphaera (Farr and Rossman 2020). In Taiwan, powdery mildew has been briefly reported on zinnia without detailed descriptions (Hsieh 1983). This study confirmed P. xanthii as a causal agent of powdery mildew in Taiwan and the awareness of the disease may benefit the floral industry. To our knowledge, this is the first confirmed report of P. xanthii on Z. elegans in Taiwan.

Complete Genome Sequence Resource for the Necrotrophic Plant-Pathogenic Bacterium Dickeya dianthicola 67-19 isolated from New Guinea Impatiens

New Guinea Impatiens (NGI, Impatiens hawkeri) are popular bedding plants that can be affected by a number of pathogens. Using 16S rDNA sequencing and genus-specific PCR, we identified the first Dickeya dianthicola strain isolated from NGI presented with blackleg symptoms, herein designated as D. dianthicola 67-19. Here, we report a high-quality complete and annotated genome sequence of D. dianthicola 67-19. The 4,851,809 bp genome was assembled with Nanopore reads and polished with Illumina reads, yielding 422× and 105× coverage, respectively. This closed genome provides a resource for future research on comparative genomics and biology of D. dianthicola, which could translate to improved detection and disease management.