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Jean Carlos Bettoni, Aike Anneliese Kretzschmar, Remi Bonnart, Ashley Shepherd and Gayle M. Volk

The availability of and easy access to diverse Vitis species are prerequisites for advances in breeding programs. Plant genebanks usually maintain collections of Vitis taxa as field collections that are vulnerable to biotic and abiotic stresses. Cryopreservation has been considered an ideal method of preserving these collections as safety back-ups in a cost-effective manner. We report a droplet vitrification method used to cryopreserve 12 Vitis species (Vitis vinifera cvs. Chardonnay and ‘Riesling, V. actinifolia, V. aestivalis, V. jacquemontii, V. flexuosa, V. palmata, V. riparia, V. rupestris, V. sylvestris, V. ficifolia, V. treleasi, and V. ×novae angeliae) using shoot tips excised from plants grown in vitro. Our results demonstrated wide applicability of this technique, with regrowth levels at least 43% for 13 genotypes representing 12 Vitis species. We demonstrated that the droplet vitrification procedure can be successfully replicated by technical staff, thus suggesting that this method is ready for implementation.

Open access

Jia Liu, Tingting Xue and Yongbao Shen

Freshly harvested empress tree (Paulownia elongata) seeds have physiologic dormancy. The aim of this study was to investigate the effects of exogenous and endogenous nitric oxide (NO) on the dormancy and germination of empress tree seeds. After treatment with different concentrations of sodium nitroprusside (an NO-releasing compound) solution, the germination percentage of seeds under 12 h of continuous light was significantly greater. Seed germination percentage was promoted significantly by 10–4 M sodium nitroprusside plus cold stratification compared with seeds treated with cold stratification only. At different hours during imbibition, empress tree seeds treated with 2-(4-carboxyphenyl)-4, 4, 5, 5- tetramethylimidazoline -1-oxyl-3-oxide potassium salt (c-PTIO), NG-nitro-L-arginine methyl ester (L-NAME), and sodium tungstate showed reduced seed germination percentages. During the early hours of imbibition, c-PTIO or sodium tungstate treatment inhibited seed germination significantly. The results showed that both exogenous and endogenous NO can release empress tree seed dormancy. Endogenous NO oxide was involved in dormancy release and germination of seeds during the early stages of imbibition. Wider application of NO may be used for breaking seed dormancy in other species.

Open access

Robert F. Heyduck, Steven J. Guldan and Ivette Guzmán

In a two-part study, we examined the effect of sowing date and harvest schedule on the yield of spinach (Spinacia oleracea) grown during the winter in 16 × 32-ft-high tunnels in northern New Mexico. Each part of the study was conducted for two growing seasons and took place between 2012 and 2015. In Study A (2012–13 and 2013–14), spinach was sown four times at roughly 2-week intervals (mid-October, early November, mid-November, and early December) and plant density (plants per square foot), plant height (centimeters), and yield (grams per square foot) were measured for three harvests in mid-January, mid-February, and mid-March. The earliest sowing date had the least-dense stands, and plant density increased with each subsequent sowing. The two earliest sowing dates had significantly higher season-long yield than the later two sowings. In Study B (2013–14 and 2014–15), all plots were sown in mid-October, but harvest schedule treatments were staggered such that harvests began at 9, 11, 13, or 15 weeks after sowing and continued at irregular intervals. Treatment 2, with harvests beginning after 11 weeks, had the greatest season-long yield, slightly greater than when harvests began at 9 weeks, and significantly more than when harvest began 13 weeks or later. More importantly, a staggered harvest schedule can provide spinach weekly for direct marketing opportunities.

Open access

Ariana P. Torres, Susan S. Barton and Bridget K. Behe

As more individuals use the Internet for business and leisure, the opportunities for firms to promote products and services and to communicate with consumers online increases. The objective of this study was to investigate green industry managerial decisions to engage in online advertising and how much to invest while determining the main drivers contributing to these decisions. A double-hurdle model analyses of 1735 responses to the 2014 National Green Industry Survey, which gathered information on business practices, showed >40% of green industry business invested in online advertising. Typically, businesses investing in online advertising spent more than 43% of all advertising expenditures in online methods, including websites, social media, and newsletters. Furthermore, the decision to engage in online advertising was driven by the percentage of wholesale and contract sales, market access, firm size, product mix, and business owners’ perceptions. Results also showed that the amount of dollars invested in online advertising depended on firm size, tools used to find customers, location, and business owners’ perceptions. Our findings can help extension personnel and policymakers with the design and deliver social media training and educational events. Our findings can also help green industry businesses understand the two-step nature of the decision to invest in online advertising.

Open access

George E. Boyhan, Suzanne O’Connell, Ryan McNeill and Suzanne Stone

Organic production is a fast-growing sector of agriculture in need of variety evaluations under their unique production systems. This study evaluated 16 watermelon (Citrullus lanatus) varieties for their performance characteristics under organic production practices. Plants were grown on plastic mulch-covered beds on land that had been certified organic in accordance with the U.S. Department of Agriculture National Organic Program. Six of the entries were F1 hybrids; the remaining entries were open-pollinated (OP) varieties. Of the 10 OP varieties, three were considered heirloom varieties, including Cream of Saskatchewan, Georgia Rattlesnake, and Moon & Stars. ‘Georgia Rattlesnake’ was the highest yielding variety and had the greatest average fruit weight. Along with ‘Georgia Rattlesnake’, ‘Nunhems 800’, ‘Nunhems 860’, ‘Orangeglo’, and ‘SSX 8585’ were included in the top five yielding varieties. The top five yielding varieties had fruit size that averaged more than 20 lb. Fruit size correlated with rind thickness, with lighter fruit having thinner rind (Pearson’s correlation, r = 0.779), which is not unexpected. ‘Sangria’ had the greatest average soluble solids content at 11.2%, which was greater than all entries with soluble solids less than 10%.

Open access

Analena B. Bruce, Elizabeth T. Maynard and James R. Farmer

High tunnels are an increasingly popular part of the infrastructure among small and diversified farms that market their products directly to consumers. In addition to extending the growing season, research has strongly indicated that high tunnels can increase yield, enhance shelf life, and improve the quality of crops grown. The objective of this study was to gain a better understanding, from the perspective of farmers, of the challenges and opportunities associated with adopting high tunnels for specialty crops in Indiana. We collected information through a case study that included questionnaires and in-depth interviews with 20 farmers. We found that the additional labor and time requirements of high tunnel production, the increased complexity of high tunnel production, soil fertility, and disease management, and limited winter markets posed the greatest challenges. The ability to differentiate their products based on higher quality and longer shelf life, the ability to obtain a premium price, the ability to have a source of income during the off-season, and the ability to produce complementary crops were the most important opportunities for using high tunnels. This research implied ways to expand opportunities and reduce barriers to maximizing the potential of high tunnels. Understanding the human dimensions of managing high tunnels is important for providing extension educators and Natural Resources Conservation Service field staff with better knowledge of the common difficulties and benefits of this technology so they are better able to advise farmers considering investing in a high tunnel. A focus on the human dimensions is also helpful for identifying research priorities to evaluate new approaches to decreasing problems and increasing benefits. Consequently, this study provided an in-depth understanding of farm-level challenges associated with high tunnel adoption to improve future research in diverse fields.

Open access

Youngsuk Lee, Hun Joong Kweon, Moo-Yong Park and Dongyong Lee

Nutrient content assessment of plant tissues is widely performed by farmers to determine the appropriate amount of fertilization to use for their crops. A nondestructive leaf chlorophyll meter is one of the most commonly used devices for performing field assessments of the nutrient status of leaves. However, it is challenging to use a chlorophyll meter to assess the nutritional status of perennial plants, such as the apple (Malus ×domestica) tree, because of the difficulty estimating nitrogen (N) during the entire growing period. We compared the chlorophyll meter readings with leaf nutrient profiles collected from young ‘Arisoo’/M.9 apple trees throughout the growing period. A significant positive correlation between the chlorophyll meter readings and leaf N content was found from May to August during the midseason. Regression analysis indicated that the best sampling time for predicting the foliar N content of apple tress is from late June to late July. This result suggests that a reliable leaf N assessment can be performed in a rapid, nondestructive way in apple orchards.

Open access

Derald Harp, Gaye Hammond, David C. Zlesak, Greg Church, Mark Chamblee and Steve George

Landscaping today involves the struggle to balance aesthetically pleasing plants while minimizing the impact on the environment, reducing water usage, decreasing fertilizer use, and eliminating or significantly reducing pesticide usage. Roses (Rosa sp.), although seen as challenging plants, remain the most popular flowering shrub in the United States. The identification of new cultivars that combine beauty, pest and disease resistance, and drought tolerance are important to Texas landscapes. Sixty roses were assessed over a 3-year period to determine flowering, drought tolerance, disease resistance, and overall landscape performance in minimal-input gardens in north central Texas. Atypical weather during the study had a significant impact on performance. A 2-year drought (2010–11) was accompanied by the hottest summer on record (2011), which included a record number of days of at least 100 °F or higher. As a result, supplemental irrigation was provided three times both summers. Roses generally fared well under these conditions and survived the drought. Flowering was most abundant during the spring and fall, and it was least abundant in the summer. Powdery mildew [PM (Sphaerotheca pannosa var. rosae)] was a minor problem. Nine of 60 cultivars developed no visible symptoms of PM during the study. Most PM occurred in Spring 2010, with very little found after June; none was found in 2011. Black spot [BS (Diplocarpon rosae)] was serious for some cultivars, but most were BS-free; RADrazz (Knock Out®) and Lady Banks White had no observed BS during the study. BS occurred mostly in May, June, and November. Overall landscape performance ratings were high, with 23 cultivars having a mean landscape performance rating equal to or better than the Belinda’s Dream standard. The best-performing cultivars were RADrazz (Knock Out), RADcon (Pink Knock Out®), RADyod (Blushing Knock Out®), WEKcisbaco (Home Run®), and Alister Stella Gray. This study was able to identify many other highly performing roses in north central Texas.

Open access

Flavia T. Zambon, Davie M. Kadyampakeni and Jude W. Grosser

There is accumulating evidence that root system collapse is a primary symptom associated with Huanglongbing (HLB)-induced tree decline, especially for commercial sweet orange and grapefruit trees on Swingle and Carrizo rootstocks. Maintaining root health is imperative to keep trees productive in an HLB-endemic environment. Preliminary greenhouse and field studies have shown that HLB-impacted trees had secondary and micronutrient deficiencies that were much greater in the roots than in the leaves, and that treatments containing three-times the recommended dose of manganese (Mn) improved tree health and growth and increased feeder root density in greenhouse trees. These results suggested that trees in an HLB-endemic environment have higher specific micronutrient requirements than those currently recommended. To test this hypothesis, established Vernia sweet orange grafted onto rough lemon rootstock trees were divided into eight supplemental CRF nutrition treatments (including two-times and four-times the recommended doses of Mn and boron) using a randomized complete block design in a commercial grove in St. Cloud, FL. The following supplemental nutrition treatments were used: no extra nutrition (control); Harrell’s–St. Helena mix 0.9 kg per tree; Harrell’s with 32 g of Florikan polycoated sodium borate (PSB) per tree; Harrell’s with 90 g of TigerSul® Mn sulfate (MS) per tree; Harrell’s with 32 g of PSB and 90 g of MS per tree; 180 g of MS per tree; 64 g of PSB per tree; and 180 g of MS plus 64 g of PSB per tree applied every 6 months since Fall 2015. Leaf and soil nutritional analyses were performed in Mar. 2017, Sept. 2017, and May 2018; a quantitative polymerase chain reaction was performed for Candidatus Liberibacter asiaticus (CLas) titer estimation in Nov. 2017. Significantly higher cycle threshold (Ct) values indicating reduced CLas bacterial populations were observed in trees that received the higher doses of Mn, especially those receiving four-times the recommended dosage of Mn (180 g Mn). Many trees exhibited Ct values of 32 or more, indicating a nonactive infection. Fruit yields of these trees were also increased. No significant differences in juice characteristics, canopy volume, and trunk section area were found between control plants and plants treated with 180 g Mn. Soil and leaf nutrients B, K, Mn, and Zn were significantly different among treatments at various times during the study. Our results strongly suggest that overdoses of Mn can suppress CLas bacterial titers in sweet orange trees on rough lemon rootstock, thus providing a therapeutic effect that can help restore tree health and fruit yields. This response was not observed when Mn and B were combined in the overdose, suggesting an antagonistic effect from B on Mn metabolism. When an overdose of Mn is used, biological functions and tree tolerance lost due to nutritional imbalances caused by HLB might be restored. Further studies are needed to elucidate which metabolic pathways are altered by comparing overdosed and conventionally fertilized HLB-impacted trees and to determine if the observed therapeutic effects can be achieved in trees grafted to other important commercial rootstocks.

Open access

Rafael A. Muchanga, Toshiyuki Hirata and Hajime Araki

Cover crops and compost application may influence soil quality and productivity of fresh-market tomatoes. The effects of hairy vetch (HV) (Vicia villosa Roth) and livestock compost on soil C and N stocks, N availability, and tomato yield were evaluated for 2 years in a plastic high tunnel. Averaged across years, soil C and N stocks increased in plots incorporating hairy vetch and compost more than in plots with no hairy vetch and compost. When compared with baseline stocks (initial soil C and N stocks before the initiation of the examination), soil C stock increased by 3%, 2.8%, 2.6% in the HV treatment, the compost treatment, and the HV and compost treatment, respectively. In contrast, a 1.85% loss of soil C stock was observed in a no HV and no compost (bare) treatment. Soil N stocks increased in all treatments, with the greatest increase in the compost treatment (26%) and the lowest in the bare treatment (9.3%). Averaged across sampling dates, the HV treatment exhibited the greatest soil N availability and nitrate levels in leaf petiole in both years, whereas the bare treatment exhibited the lowest soil N availability and nitrate levels in leaf petiole. HV + compost and compost treatments showed a similar influence on soil N availability, but HV + compost exhibited greater nitrate levels in leaf petiole than the compost treatment. The marketable and total yields were 10% to 15% greater in the HV and the compost treatments than in the bare treatment. N uptake was 17% to 38% greater in the HV treatment than in the other treatments. Because of unstable cover crop production in the northern region, a combined application of cover crops and compost may be one of the best practices to compensate for low cover crop biomass production by increasing organic matter input to the soil, thereby improving soil quality and tomato yield.