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Open access

J. Bryan Webber, Darcy Gordon, Adolfo Rosati, Nicholas Meier, Michael Gold, and Ronald Revord

U.S. chestnut (Castanea sp.) production is expanding as knowledge of seedling cultivation and germplasm advances. Chestnuts have high starch and water content, making them highly perishable; therefore, they require cold storage immediately following harvest. Postharvest spoilage remains a significant area for improvement. Several postharvest fungi (including Fusarium sp. and Penicillium sp.) can infect chestnuts during storage, leading to spoilage and nonsellable nuts. The annual crop losses can reach up to 10%, thereby affecting trees differently. Our research objectives were to 1) evaluate spoilage incidence on the interior (i.e., pellicle, kernel) and exterior (i.e., nutshell) of the nut over the course of 200 days of cold storage on eight cultivars and 2) assess the impact of food contact-approved chlorine solution and 2% peracetic acid (PAA) with 27% hydrogen peroxide prestorage treatments for spoilage suppression on ‘Qing’ nuts. Fourteen timepoints were observed during the study period, each with four replications of 16 nuts. An additional four replicates of 16 ‘Qing’ nuts were treated prestorage and observed over seven time points. The incidence of spoilage was reported as the percentage of nonsellable nuts for each treatment and cultivar at four timepoints. The nut interior showed the highest spoilage incidence after 200 days, with four cultivars having >30% nonsellable nuts. Overall, the cultivars had an average of 10% nonsellable nuts from interior spoilage after 60 days in storage. ‘Hong Kong’ had the highest percentage of nonsellable nuts by the end of the study at 60%, whereas ‘Qing’ and ‘Mossbarger’ had the lowest rates, with only 14% nonsellable nuts. Spoilage of the exterior, although less frequent, is visible to buyers and impacts nut marketability. ‘Kohr’ had the highest percentage of nonsellable nuts because of exterior spoilage (35.9%). ‘Mossbarger’ had the lowest percentage of nonsellable nuts because of exterior spoilage (3.1%). ‘Qing’ nuts treated with 500 ppm chlorine and 100/200 ppm PAA demonstrated reduced exterior spoilage with longer storage times. Prestorage treatment did not show efficacy for reducing interior spoilage. This study provides a preliminary report of evidence that cultivar differences influence the spoilage incidence and supports taking nuts to market within 60 days of harvesting. These preliminary data also inform breeding parent combinations and studies of inheritance for postharvest spoilage tolerance at the University of Missouri Center for Agroforestry breeding program.

Open access

Dan Wang, Yang Yang, Fengyi Li, Sheng Zhou, Guiling Liu, Juan Yang, Wangbin Ye, and Ling Wang

Rhododendron dauricum is an extremely cold hardy, semievergreen, multibranched shrub that is distributed widely throughout northeastern China, Mongolia, Japan, the Korean Peninsula, and Russia (Yang et al., 2020). It grows in a wide range of environmental conditions, from forests to rocky landscapes; produces flower buds during severe winters; and blooms in early spring even if it is covered in snow (Polezhaeva et al., 2018). It is a valuable ornamental landscape species in the Great Khingan Mountains of northeastern China, where the annual average temperature is –22.27 to 9.67 °C (Zhang et al., 2018). It

Open access

Bryan K. Sales, David R. Bryla, Kristin M. Trippe, Carolyn F. Scagel, Bernadine C. Strik, and Dan M. Sullivan

Biochar, as a soil amendment, has been reported to improve plant growth by increasing soil moisture and retaining nutrients. In a previous 12-week greenhouse study with highbush blueberry (Vaccinium hybrid), we found that amending soil with biochar alone or in combination with bokashi (fermented wheat bran) increased plant growth relative to unamended soil. The biochar was produced from mixed conifer species during conversion of wood to energy. In the current study, we aimed to validate the greenhouse findings under field conditions in western Oregon. The specific objectives of this 2-year study were to determine the effect of amending soil with biochar or a combination of biochar and bokashi on growth and early fruit production during establishment of northern highbush blueberry (Vaccinium corymbosum L.). To achieve these objectives, we transplanted ‘Duke’ blueberry plants into soil that was either unamended or amended with biochar or 4:1 (v/v) mixtures of biochar and bokashi or biochar and douglas fir [Pseudotsuga menziesii (Mirb.) Franco] sawdust. Each amendment was either applied in the planting hole or incorporated into the row. A treatment with douglas fir sawdust incorporated into the row was also included and represented the industry standard for the region. Plants grown in soil amended with biochar (in the planting hole or row) had 40% to 74% greater total dry weight at the end of the first growing season and 70% to 82% greater fruit yield in the second season than those grown with no amendments or in soil amended with sawdust. However, leaf Mg concentrations were lower with biochar, suggesting it could limit Mg uptake in blueberry. Soil amended with sawdust, on the other hand, was higher in organic matter, microbial activity, and wet stable aggregates than the other soil treatments but resulted in lower leaf N concentrations during the second year after planting. Unlike in the greenhouse study, biochar had no effect on root colonization by mycorrhizal fungi, and there was no benefit to using biochar with bokashi. Adding 4 L of biochar to the planting hole was considerably more economical than applying it to the row and cost $1320/ha less than the industry standard of incorporating sawdust in the row. These findings indicate that biochar is a promising soil amendment for commercial production of highbush blueberry.

Open access

Kim S. Lewers and John M. Enns

Cordial, a late-season, short-day strawberry (Fragaria ×ananassa Duch. ex Rozier), follows Keepsake as the second cultivar resulting from a U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) effort at Beltsville, MD, to develop strawberries with increased shelf life (Lewers et al., 2019). ‘Cordial’ and ‘Keepsake’ strawberries had similarly low proportions of fruit rot and degradation in 2 weeks of refrigerated storage compared with other cultivars and breeding selections. ‘Cordial’ has consistently provided very high yields and very low rot with no fumigation or fungicides in an annual plasticulture system at Beltsville, MD. ‘Cordial’ strawberries are

Open access

Sarada Krishnan, Heather Kirk-Ballard, Esther McGinnis, and Lauren Garcia Chance

The retail gardening industry in the United States is expected to reach $50 billion by 2023, and it is a significant driver of the agricultural economy. To meet the corresponding demand for information, consumer horticulture (CH) professionals will need to develop innovative digital outreach, research-based solutions, a concerted recruitment of youth, and enhanced collaborations. To understand the current gaps in CH research and the extent of the involvement of public gardens in CH, surveys were conducted among the two groups, CH/extension researchers and staff of public gardens. The results of the surveys were presented at the virtual conference of the American Society for Horticultural Science on 12 Aug. 2020 during a workshop hosted by the Consumer Horticulture and Master Gardener Professional Interest Group. The workshop included four presentations, and two of those are discussed in this paper: 1) research gaps in CH and 2) bridging the divide between CH and public gardens. Among researchers, even though there was a general understanding of CH, there was a disconnect in participants’ perceptions of the roles of CH in the economy and recreation. The greatest knowledge gap was in basic horticultural practices. Regarding public garden professionals, there needs to be a concerted effort to educate them about CH so they can provide a consistent message to their audiences and the general public.

Open access

Wendell J. Hutchens, Jordan C. Booth, J. Michael Goatley, and David S. McCall

Spring dead spot (SDS), caused by Ophiosphaerella spp., is among the most damaging diseases to hybrid bermudagrass (Cynodon dactylon × transvaalensis) in areas where winter dormancy occurs. Management strategies that aid in turfgrass recovery from SDS damage have not been widely studied. An experiment was conducted in Blacksburg, VA, in 2019 and 2020, to determine the influence of various cultural practices on bermudagrass recovery from SDS damage. Fertility and cultivation were applied in the late spring/early summer, which is earlier than normal for cultivation practices for bermudagrass, to test their effectiveness in aiding bermudagrass recovery from SDS damage. The main effects of fertility and cultivation were arranged in a 2 × 3 factorial design with vertical mowing, solid-tine aerification, and no cultivation applied with urea (48.8 kg⋅ha−1 N) sprayed at trial initiation and 2 weeks later or without urea. Plots were assessed for the percent of SDS throughout the study. Data were analyzed as the percent change relative to the initial assessment to measure bermudagrass recovery. The main effect of fertility increased bermudagrass recovery from SDS damage in both 2019 and 2020. The main effects of vertical mowing and solid-tine aerification reduced bermudagrass recovery from SDS damage in 2020. These data suggest that two properly timed nitrogen fertilization applications at 48.8 kg⋅ha−1 optimized bermudagrass recovery from SDS damage, whereas late spring/early summer cultivation without fertility may inhibit bermudagrass recovery.

Open access

Michael Alden and James E. Faust

The effect of night length (NL) on the flower development of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) ‘Prestige Red’ was evaluated. Flower initiation occurred by subjecting plants to a 14-hour NL for 10 or 17 days, termed short-day (SD) treatments, and then transferring the plants to each of four NL treatments (11, 12, 13, or 14 hours) to observe the effects of NL on flower development. The plants grown continuously with the 14-h NL treatment were the control group. The timing of first color, visible bud, and anthesis were recorded during flower development, and bract and leaf data were collected at anthesis. Leaf number was unaffected by the SD or NL treatments, suggesting that flower initiation occurred during the 10-day SD treatment before the start of NL treatments; thus, the NL treatments only affected flower development. The timing of first color and visible bud were significantly delayed with the 10-day SD × 11-hour NL treatment relative to the 14-hour NL control; however, first color and visible bud were not delayed with the 17-day SD × 11-hour NL treatment. The 11-hour NL treatment resulted in fewer plants reaching anthesis, and these plants had fewer stem bracts and less bract color development compared with the 12-hour, 13-hour, and 14-hour NL treatments. Therefore, an 11-hour NL is suboptimal for flower development; nonetheless, significant development did occur. The 12-hour NL resulted in less color development than the 13-hour and 14-hour NL treatments in the lowest stem bract positions, but the plants had a commercially acceptable appearance. These results demonstrate that minimal differences in flower development occur with NL ≥12 hours, but that optimal development required NL ≥13 hours.

Open access

Kristin E. Neill and Ryan N. Contreras

Vaccinium ovatum (evergreen huckleberry) is an evergreen shrub native to the Pacific Northwest. Evergreen huckleberry is diploid (2n = 2x = 24), but unreduced gametes have been reported that facilitated in interspecific tetraploids. To our knowledge, tetraploid forms of evergreen huckleberry have not previously been evaluated. There is interest in this species as a native, edible, evergreen landscape shrub, but it requires improvement of the fruit and plant qualities for an eventual cultivar release. To obtain variation in plant qualities, we induced polyploidy in a collection of plants in 2013. The purpose of this study was to assess the impacts of polyploidy on the fruit and plant qualities of V. ovatum. This fruit and plant quality study provides a contribution to the scientific knowledge base that is currently lacking for evergreen huckleberries. Plant qualities were determined by measuring plant height and width, obtained in Fall 2017. The fruit volume (mm3) and for soluble solids content (SSC, °Brix) were measured using a digital caliper and a digital refractometer, respectively. Measurements were taken on diploid, mixoploid, and tetraploid (2x, 2x + 4x, 4x) cytotypes, once in 2017, five times over 9 weeks in 2018, and three times over 9 weeks in 2019. Tetraploids had larger fruit than diploids in 2017 (P < 0.0001), suggesting there was a gigas effect from polyploidy in evergreen huckleberries. However, during 2018 and 2019, tetraploid fruit was smaller than that of diploid and mixoploid genotypes. Differences were observed in diploid fruit volume among all years (P < 0.0001) such that 2019 was largest and 2017 was smallest. It is unclear what led to this variation. In tetraploids, SSC was statistically significant among years (P = 0.0002) such that 2017 was highest and 2019 was lowest. Although our preliminary data suggested that induced polyploidy may result in larger fruit, this was not observed in subsequent years, and it does not appear that tetraploids necessarily will have larger or sweeter fruit. However, these tetraploids may facilitate crossing with other species at the tetraploid level as a means for improvement of various traits.

Open access

Juan Yang, Fengyi Li, Sheng Zhou, Lijuan Fan, and Ling Wang

Iris sanguinea, a perennial, cold-tolerant, herbaceous flower, is widely distributed in northeast China. It is a valuable ornamental landscaping plant because of its rich and unusual flower colors and patterns (Lian et al., 2016). With the increasing demands of the market, I. sanguinea is becoming a new and distinctive landscaping and cut flower. Using conventional breeding methods, we have successively bred and released 14 new cultivars of I. sanguinea. These include cultivars with new flower colors, such as Beautiful Lotus (Wang et al., 2016), Chun Xin (Wang et al., 2018

Open access

Osama Mohawesh, Ammar Albalasmeh, Sanjit Deb, Sukhbir Singh, Catherine Simpson, Nour AlKafaween, and Atif Mahadeen

Colored shading nets have been increasingly studied in semi-arid crop production systems, primarily because of their ability to reduce solar radiation with the attendant reductions in air, plant, and soil temperatures. However, there is a paucity of research concerning the impact of colored shading nets on various crops grown under semi-arid environments, particularly the sweet pepper (Capsicum annum) production system. This study aimed to investigate the effects of three colored shading net treatments (i.e., white, green, and black shading nets with 50% shading intensity and control with unshaded conditions) on the growth and instantaneous water use efficiency (WUE) of sweet pepper. The results showed that all colored shading nets exhibited significantly lower daytime air temperatures and light intensity (22 to 28 °C and 9992 lx, respectively) compared with the control (32 to 37 °C and 24,973 lx, respectively). There were significant differences in sweet pepper growth performance among treatments, including plant height, shoot dry weight, leaf area, leaf chlorophyll content, and vitamin C in ripened fruit. The enhanced photosynthetic rates were observed in sweet pepper plants under the colored shading nets compared with control plants. WUE increased among the colored shading net treatments in the following order: control ≤ white < black < green. Overall, the application of green and black shading nets to sweet pepper production systems under semi-arid environments significantly enhanced plant growth responses and WUE.