The objective of these experiments was to evaluate the reaction of ‘Snow Angel’ coral bells (Heuchera sanguinea) and Orange Carpet hummingbird trumpet (Epilobium canum ssp. garrettii ‘PWWG01S’) to repeated foliar applications of three plant growth regulators at two application rates. The plant growth regulators applied during a stock plant study and followed by a propagation study were 200 and 400 ppm ethephon, 250 and 500 ppm benzyladenine, and 50 and 100 ppm gibberellic acid 4 and 7 (GA4+7) + benzyladenine. The stock plant study was conducted to assess the efficacy of plant growth regulators, vegetative growth (height and width growth index), the number of vegetative cuttings, as well as the fresh weight (FW) and dry weight (DW) of the harvested vegetative cuttings. The propagation study was conducted to determine the effects of the plant growth regulator treatments on the rooting of the vegetative cuttings. The stock plant study showed that GA4+7 + benzyladenine (50 and 100 ppm) significantly increased production of ‘Snow Angel’ coral bells cuttings compared with all other treatments. However, no significant differences in FW or DW were observed with ‘Snow Angel’ coral bells between treatments. In the propagation study, no significant difference in rooting percentage was observed after 4 weeks. The Orange Carpet hummingbird trumpet stock plant study resulted in a greater number of vegetative cuttings with GA4+7 + benzyladenine (50 and 100 ppm) and benzyladenine (250 ppm) treatments. Fresh weight of vegetative cuttings harvested from plants treated with GA4+7 + benzyladenine (50 or 100 ppm) were the lowest. The only treatment that showed increased vegetative cutting production with no effect on FW was benzyladenine (250 ppm) on Orange Carpet hummingbird trumpet.
Sean J. Markovic and James E. Klett
Elisa Solis-Toapanta, Andrei Kirilenko and Celina Gómez
Social media platforms such as Reddit, centered on user-generated, anonymous discussions, can facilitate the exchange of information and resources across niche online communities known as “subreddits.” Using data mining tools and content analysis methods, our objectives were to identify recurring questions and characterize comment (“response”) accuracy from four subreddits focused on hydroponic indoor gardening (r/hydro, r/Hydroponics, r/UrbanFarming, and r/Aerogarden). A total of 1617 original posts (OPs) were classified into one of ten topics and 4891 primary responses were analyzed for accuracy. The three topics with the most OPs (production systems, plant lighting, and root-zone environment), which accounted for 50% of the total OPs, were subcategorized and inductively analyzed. Most posts in the analyzed subreddits related to confusion regarding the design and implementation of appropriate hydroponic production systems. In addition, misinformation about plant lighting is a major part of discussions about growing plants indoors. There are also knowledge gaps regarding nutrient solution management, particularly about fertilizer formulation, pH balance, and on the impact that solution temperature has on plant growth and development. In general, there were no differences among response accuracy for all topics included in our analysis. However, regardless of topic, responses for most OPs had less than 50% accuracy, which demonstrates that misinformation can be disseminated in social media platforms such as Reddit. As suggested by the results of this study, targeted, open access research and outreach efforts offer an opportunity to address knowledge gaps among consumers interested in indoor gardening.
Dong Sub Kim, Mark Hoffmann, Steven Kim, Bertha A. Scholler and Steven A. Fennimore
Steam has long been used to disinfest greenhouse soils. However, there is increasing interest in expanding the use of steam for in-field soil disinfestation as an alternative to chemical fumigants. Previous studies demonstrated that allyl-isothiocyanate (AITC) reduced viability of weed seeds and plant pathogen propagules, but AITC has a low vapor pressure and is relatively immobile in soil. Heat has been used in the past to enhance the mobility of soil fumigants such as methyl bromide (i.e., “hot gassing”). The effect of steam heat on the mobility of AITC is unknown. The objective of this study was to investigate the potential synergistic effect of steam plus ATIC against weed seeds and a plant pathogen. AITC alone did not reduce the viability of the four weed species and the number of Verticillium dahliae microsclerotia. The steam + AITC treatment reduced the viability of V. dahliae at 12.5 and 18 cm distances by 82% and 88%, respectively, and knotweed and nettle seeds at 70 cm from injection point by 75% and 86%, respectively, from the center of microplots compared with steam alone. The results suggest that AITC and steam have a complementary effect on soilborne pests because steam increases the mobility of AITC.
Chunxian Chen and William R. Okie
Coleman L. Etheredge, Tina M. Waliczek and Pratheesh Omana Sudhakaran
A university faculty-managed and student-run service-learning program provides seasonal plants and floral designs for holidays and special events on campus. Native and well-adapted plants for client personal use are also promoted and sold throughout the semester. Students propagate and grow greenhouse and nursery crops and create floral designs through service-learning applications in classes. Floral designs and greenhouse/nursery products are advertised via e-mail to members of the university's faculty and staff. The purpose of this study was to document program fundraising over time, as well as to measure the experiential value to the students and the quality of life benefits to the campus community. Economic benefits were evaluated by reviewing overall and average costs and earnings from the program over a 13-year period. Results indicated the average profits for the program were $6578 annually, with most sales occurring during the late spring semester. Surveys collected qualitative data from students participating in the program and indicated the experience was a valuable hands-on horticultural teaching tool, but also helped students build confidence, learn business skills in management and networking, and find their passion within the industry. Unsolicited comments from faculty and staff found that the program brought joy, had educational value, and provided a service to departments.
Nohra Rodríguez Castillo, Daniel Ambachew, Luz Marina Melgarejo and Matthew Wohlgemuth Blair
Global demand for juice of the purple passion fruit, Passiflora edulis f. edulis, is growing, making it a promising species for farmers to grow in the highland tropics, to which it is adapted. However, research centers and private companies have done little to produce new high-yielding varieties. The objective of the present study, therefore, was to evaluate the agronomic and morphological characteristics of 50 passion fruit genotypes across two different elevations and agro-ecological sites as a base for germplasm enhancement. Three groups of genotypes were commercial cultivars (8 genotypes), genebank accessions (8), and landraces (34) collected from throughout the highlands of Colombia. The locations were at 1800 m above sea level (masl) (Pasca), in a place where cultivation of passion fruits is common; and at 2500 masl (Susacón), at a higher elevation site compared with most commercial plantings equal to a new agroecology for cultivation of the crop. Results indicated that the mid-elevation site produced higher yields (kg fruit/plant) than the high elevation site, although some landraces were highly productive there. Commercial cultivar and genebank accessions clustered together in a principal component analysis (PCA); while landraces showed high levels of variation in the trait descriptors with five different clusters. Therefore, landraces of purple passion fruit contained greater genetic diversity than commercial cultivars or the genebank, and breeding programs for the crop should use landraces to increase diversity of varieties available to producers and to further expand the crop to new regions, at higher elevations, or with different agro-ecologies.
Youping Sun, Liqin Li, Yuxiang Wang and Xin Dai
Spirea (Spiraea sp.) plants are popular landscape plants in Utah and the Intermountain West United States. Spiraea betulifolia, S. japonica, S. media, S. nipponica, and S. thunbergii were evaluated for salinity tolerance in a greenhouse experiment. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solution at an EC of 3.0 or 6.0 dS·m−1 for 8 weeks. At the end of the experiment, all spirea plants survived and retained good visual quality, with average visual scores greater than 4 (0 = dead, 5 = excellent) when irrigated with saline solution at an EC of 3.0 dS·m−1, with the exception of S. thunbergii, which showed slight foliar salt damage and an average visual score of 3.8. When irrigated with saline solution at an EC of 6.0 dS·m−1, all S. thunbergii plants died, S. media exhibited severe foliar salt damage and an average visual score of 1.5, and S. betulifolia, S. japonica, and S. nipponica displayed slight-to-moderate foliar salt damage and average visual scores greater than 3. Regardless of spirea species, shoot dry weight decreased by 20% and 48% when irrigated with saline solution at ECs of 3.0 and 6.0 dS·m−1, respectively, compared with the control. Saline solution at an EC of 3.0 dS·m−1 did not affect net photosynthesis (Pn) of all spirea species except S. nipponica, but saline solution at an EC of 6.0 dS·m−1 decreased the Pn of all species by 36% to 60%. There were 37, 7, 36, 21, and 104 times more sodium (Na+) concentrations in leaf and 29, 28, 28, 13, and 69 times more chloride (Cl−) concentrations in leaf than in the control when S. betulifolia, S. japonica, S. media, S. nipponica, and S. thunbergii were irrigated with saline solution at an EC of 6.0 dS·m−1. Correlation analyses indicated that foliar salt damage and reduced plant growth and photosynthesis were induced mainly by Cl− ions accumulated in the spirea leaves. S. thunbergii was the most sensitive species; it had high mortality and low visual quality at both salinity levels. Spiraea japonica, S. nipponica, and S. betulifolia were relatively more tolerant and had good visual quality at elevated salinity compared with S. media and S. thunbergii. These research results are valuable for growers and landscape professionals during plant selection for nursery production using low-quality water and landscapes in salt-prone areas.
Guanxing Hu, Chao Gao, Xiaoming Fan, Wenfang Gong and Deyi Yuan
Camellia oleifera, a major woody oil plant, has a low oil yield because of self-incompatibility. For commercial oil production, compatible pollen and optimal cross-pollination combinations are required. To evaluate the effects of pollination compatibility and pollen source on oil yield and quality, four C. oleifera cultivars—Huashuo (HS), Huajin (HJ), Huaxin (HX), and Xianglin XLC15 (XL)—were subjected to self-, cross-, and natural pollination. Pollen compatibility, oil yield, and quality indices were analyzed. There were no significant differences in pollen germination and tube growth between self- and cross-pollination. Following self-pollination, fertilization was unsuccessful, resulting in severe ovule dysplasia; cross-pollination decreased the ovule abortion rate. Pollen source significantly affected the fruit set, fruit traits, seed traits, and fatty acid content, implying xenia in C. oleifera. In cross-pollinated plants, HX pollen produced more seeds, and HJ pollen increased linoleic acid content relative to naturally pollinated plants. For the XL and HS combinations, linolenic acid contents were significantly higher than other pollination combinations. However, oleic acid content was not significantly affected by pollen source, in any of the cultivars. Cultivar HX was, therefore, the most effective pollen donor, and HS × HX was the optimal cross-pollination combination for improving oil yield and sustainability.
Kshitij Khatri, Natalia Peres, Joseph Noling and Nathan Boyd
The “Florida 3-way” consists of chloropicrin 35% + 1,3-dichloropropene 65% followed by minicoulter application of metam potassium. We evaluated the efficacy of a modified version of the Florida 3-way in which chloropicrin 35% + 1,3-dichloropropene 65% was used as primary bed fumigant and consisted of different drip tape application timings (at the time of bed formation and 2 weeks after bed formation) of metam potassium or the use of herbicides (sulfentrazone and s-ethyl dipropylthiocarbamate) as the supplemental application for the control of purple nutsedge (Cyperus rotundus) in strawberry (Fragaria ×ananassa) fields. Efficacy of modified Florida 3-way was not significantly different from standard Florida 3-way; however, supplemental herbicide such as s-ethyl dipropylthiocarbamate and sulfentrazone provided better purple nutsedge control than supplemental metam potassium application in one of two experimental growing seasons. Addition of metam potassium to the chloropicrin 35% + 1,3-dichloropropene 65% did not result in additional purple nutsedge control in Florida 3-way, which indicates the limitations of this approach.
Donnie K. Miller, Thomas M. Batts, Josh T. Copes and David C. Blouin
Commercialization of crops tolerant to application of 2, 4-dichlorophenoxyacetic acid (2,4-D) and dicamba is a cause of major concern for sweetpotato (Ipomoea batatas) producers regarding potential negative impacts due to herbicide drift or sprayer contamination events. A field study was initiated in 2016 and repeated in 2017 to assess impacts of reduced rates of combinations of glyphosate with 2,4-D or dicamba on sweetpotato growth and production. Reduced rates of 1/10x, 1/33x, 1/66x, and 1/100x of a 1x rate of glyphosate at 1 lb/acre plus 2,4-D choline at 0.94 lb/acre and glyphosate at 1 lb/acre plus diglycolamine salt of dicamba at 0.5 lb/acre were applied to ‘Beauregard’ sweetpotato at 10 or 30 days after transplanting. With respect to visual injury, in general glyphosate plus dicamba proved to be more injurious than glyphosate plus 2,4-D, especially within the lower rate range. In most cases injury was greater at the later application timing. In either case, typical hormonal herbicide symptomology was quite evident 35 days after application. With respect to U.S. No. 1 and total (U.S. No. 1, canner, and jumbo grade) sweetpotato yield, greatest negative impact was observed with herbicide application at the upper rate range, particularly the 1/10 and 1/33x rates, and at the later application timing regardless of herbicide applied.