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Samuel F. Hutton, John W. Scott and Joshua H. Freeman
Rebecca Grube Sideman
High tunnels can facilitate production of ripe colored bell peppers (Capsicum annuum) in locations with short growing seasons by extending the length of the growing season and protecting fruit from biotic and abiotic stressors. We grew 10 cultivars of bell pepper over 3 years in a high tunnel in Durham, NH. Yields of marketable colored fruit ranged from 1576 to 2285 g/plant in 2015, from 1194 to 1839 g/plant in 2016, and 1471 to 2358 g/plant in 2017. Significant differences in marketable yield among cultivars existed only in 2015 and 2017. Of the 10 cultivars evaluated, those developed for controlled environments produced greater marketable yields than those developed for production in the field or unheated tunnels (P < 0.0001). The seasonal production patterns were similar among cultivars in all 3 years: a single peak in production occurred between 159 and 175 days after seeding, followed by much lower but steady production until frost ended each growing season. Our results demonstrate that reasonable yields of colored bell peppers can be produced in high tunnels in locations with short growing seasons. We suggest that further work may be needed to identify optimal pruning and canopy management strategies to maximize yields and fruit quality.
Archana Khadgi and Courtney A. Weber
Caneberry crops (raspberry and blackberry) are globally commercialized specialty crops with a high fresh market value. Field management of canes and harvesting of fruits can be complicated by the presence of prickles (the botanically accurate term rather than spines or thorns) on the stems, petioles, and underside of the leaves. Both field management and fruit harvesting could be simplified by the development of cultivars with prickle-free canes. Scanning electron microscopy (SEM) was used to analyze and compare prickle development in different Rubus species. Comparisons were made between prickled vs. prickle-free red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), blackberry (Rubus hybrid), complex hybrid with purple fruit (R. occidentalis × R. idaeus), and the hairy and prickled wineberry (Rubus phoenicolasius Maxim). Samples from stems and leaves with petioles attached were used for imaging. There were distinct differences between prickled vs. prickle-free phenotypes in each species. The images of prickle development suggest that prickles either develop directly from glandular trichomes (in red raspberry and wineberry) or that the signal originates from glandular trichomes (in blackberry). Black raspberry prickle development was similar to that of blackberry, suggesting that prickles developed after a developmental signal from glandular trichomes rather than as a direct development from glandular trichomes. The prickle development in the purple hybrid was unique in the presence of one-sided lumps in the trichomes, which has not been seen in any other Rubus species to date; however, both prickled and prickle-free plants exhibited simple nonglandular trichomes. Unlike previous studies, an increase in the number of simple trichomes was not specific to prickle-free plants, but rather variability among the different genotypes was observed. This study adds to the basic understanding of prickle development in the genus Rubus as a first step in the development of prickle-free versions of important cultivars through gene-editing procedures for improving the ease of field management and harvesting.
Seth D. Wannemuehler, Chengyan Yue, William W. Shane, R. Karina Gallardo and Vicki McCracken
Marker-assisted selection (MAS) use in breeding programs allows for examination of seedlings at an early stage before accumulation of high field costs. However, introducing MAS into a breeding program implies additional costs and uncertainties about effective incorporation. Previous simulations in apple (Malus ×domestica) have shown cost-effective applications of MAS. To further evaluate MAS cost-effectiveness in perennial crops, we conducted a cost-effectiveness analysis examining MAS in an upper midwestern U.S. peach (Prunus persica) breeding program. Breeding program procedures and associated costs were collected and used as input into spreadsheet-based simulations of the breeding program. Simulations compared a conventional breeding program to MAS with varying cull rates of low, medium, and high at multiple stages in the breeding cycle. Cost-effective MAS implementation was identified at the end of seedling trials with a break-even cull rate of 4%. These results inform breeders of cost-effectiveness of MAS use in a peach breeding program.
Ryan N. Contreras and Kim Shearer
Cape hyacinth (Galtonia candicans) is a geophytic herbaceous perennial from South Africa. It produces large inflorescences of pendulous white flowers during mid to late summer, followed by capsules filled with copious amounts of seed. The species has potential as a low-water-use landscape plant, but lodging and excessive seed production, which pose a risk of escape or invasion, are issues that should be addressed before marketing. Ethyl methanesulfonate (EMS) is a chemical mutagen known to induce usable mutations including dwarfing and sterility. We exposed seeds of cape hyacinth to increasing concentrations of EMS (0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1%). Increased concentrations of EMS resulted in a linear decrease in seed germination when not exposed to a presoak treatment in water before exposure to EMS. No seedlings survived or were viable to field plant at 0.6%, 0.8%, or 1%. Resulting plants were field planted in 2013 and evaluated during 2014 and 2015. In both years, the inflorescence height at first flower, average seed number per capsule, and percent lodging were reduced in EMS-treated plants compared with controls. In 2015, pollen staining was evaluated and was reduced from 83% in control to less than 3% in the 0.4% treatment. Our study demonstrated that EMS is a viable option to reduce height and decrease seed set in cape hyacinth.
Bethany A. Harris, Wojciech J. Florkowski and Svoboda V. Pennisi
Biodegradable containers of various types are available on the market and can be directly purchased by growers and homeowners. However, adoption of these containers has been slow, limiting their potential as an alternative to plastic containers. It is crucial to assess level of knowledge and use of biodegradable containers by horticultural growers and landscape service providers to help explain their slow rate of adoption by the industry. An online survey instrument was implemented to assess grower and landscaper knowledge and familiarity regarding biodegradable containers in the state of Georgia. Results indicated that 83% of horticultural growers do not purchase biodegradable containers. However, peat biodegradable containers were primarily purchased when these containers were used. Both growers and landscape service providers “neither agreed nor disagreed” that the use of biodegradable containers could improve plant growth. Growers “did not know” if using biodegradable containers “improved water efficiency.” Landscape service providers exhibited low knowledge of the wide variety of biodegradable containers available on the market as well as limited awareness of features of such containers as they pertained to plant growth.
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.
Laura Jalpa, Rao S. Mylavarapu, George J. Hochmuth, Alan L. Wright and Edzard van Santen
Use efficiency of applied nitrogen (N) is estimated typically to be <50% in most crops. In sandy soils and warmer climates particularly, leaching and volatilization may be primary pathways for environmental loss of applied N. To determine the effect of N fertilization rate on the N use efficiency (NUE) and apparent recovery of N fertilizer (APR), a replicated field study with ‘BHN 602’ tomato (Solanum lycopersicum) grown in sandy soils under a fertigated plastic-mulched bed system was conducted using ammonium nitrate as the N source at four different rates (0, 150, 200, and 250 lb/acre). Spring tomato was followed by fall tomato in the same field, a typical cropping sequence in north Florida. Fertigation of N fertilizer was applied weekly in 13 equal doses for both seasons. The highest NUE was 12.05% (spring) and 32.38% (fall), and the highest APR was 6.11% (spring) for the lowest rate of N applied (150 lb/acre). In the fall, APR was unaffected by fertilizer N rates and ranged from 12.88% to 19.39%. Nitrogen accumulation in tomato plants were similar among the three N fertilizer rates applied (150, 200, and 250 lb/acre), though compared with no N fertilizer application, significant increases occurred. Whole plant N accumulation, NUE, and APR declined or remained similar when N rates increased above 150 lb/acre. Additionally, a regression analysis and derivative of the quadratic fresh yield data showed that yields were maximized at 162 and 233 lb/acre N in the spring and fall seasons, respectively.
Jasmine Jenji Mah, David Llewellyn and Youbin Zheng
One principle for reducing undesirable stem extension in greenhouse production is to counteract the decrease in red-to-far red ratio that occurs naturally during twilight periods. This study evaluated three lighting treatments on the morphology of easter lily (Lilium longiflorum): 1) a 1-hour end-of-day treatment providing 20 μmol·m−2·s−1 of monochromatic red light (EOD R), 2) blackout curtains closed 45 to 75 minutes before sunset and kept closed until 0 to 60 minutes after sunrise (BO), and 3) a control with natural twilight (CTRL). Plants under the BO treatment were 11% shorter than CTRL, while plants exposed to EOD R did not differ in height compared with BO or CTRL. There were no treatment effects on any other measured parameters, including aspects of flowering.