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Grafting has been used for controlling certain soilborne diseases and improving abiotic stress tolerance in muskmelon (Cucumis melo) production. Grafting methods may vary considerably among geographic regions and nurseries, while excision of rootstock roots before graft healing may also be practiced, which allows root regeneration of the grafted plants. In this greenhouse study, four grafting methods including hole insertion, one-cotyledon, noncotyledon, and tongue approach methods were examined for their impacts on plant growth and root characteristics of ‘Athena’ muskmelon grafted onto ‘Strong Tosa’ interspecific hybrid squash rootstock (Cucurbita maxima × C. moschata). Nongrafted rootstock and scion plants were included as controls. Both the grafted and nongrafted plants were examined with or without root excision. The practice of root excision was unsuccessful with the tongue approach method, while it did not exhibit significant effects on graft quality and growth of plants grafted with the one-cotyledon and hole insertion methods. Grafted plants with root excision started to show active and rapid root regeneration at 8 days after grafting (DAG) and reached similar root length and surface area as the root-intact plants at 16 DAG. Plants grafted with the noncotyledon method showed a different root growth pattern with decreased root length and surface area at 16 DAG. As a result, this method reduced the quality of grafted plants. No significant differences in plant growth characteristics were observed among the hole insertion, one-cotyledon, and tongue approach grafted plants.

Free access

High-tunnel strawberry (Fragaria ×ananassa) production for extended seasons has a great economic potential for small farmers. However, information on cultivars that are suitable for high tunnels is rather limited. In this study conducted in the 2014–15 season, strawberry plugs of eight June-bearing cultivars (Florida Radiance, Benicia, Camarosa, Camino Real, Chandler, Strawberry Festival, Sweet Charlie, and Winterstar) and two day-neutral cultivars (San Andreas and Albion) were evaluated for yield performance, fruit quality, and vegetative growth in organically managed high tunnels at two locations in North Carolina. Significant cultivar differences in whole-season yield were observed at Greensboro, NC; but not at Goldsboro, NC. The cultivar Florida Radiance had the highest marketable and total yields, followed by Winterstar and Chandler at Greensboro, whereas Benicia, Winterstar, and Chandler were the top producing cultivars at Goldsboro. Harvest of day-neutral cultivars San Andreas and Albion started in November. For June-bearing cultivars, Florida Radiance began to produce harvestable berries in late December, followed by Winterstar in early January. Peak harvest occurred in April for all cultivars. At the end of the season, ‘Albion’ had smaller canopy size than other cultivars. It also developed the fewest number of branch crowns and least aboveground biomass. Total soluble solid (TSS) content in April was lower than that observed early and late in the season for all cultivars, although Strawberry Festival exhibited a relatively stable TSS throughout the season. ‘Benicia’ produced the largest strawberries in the early season, but its fruit weight was remarkably reduced as the season progressed. Severe frost events occurred on 18 and 20 Feb. that caused an average of 61.5% and 32.2% open blossom damage at Greensboro and Goldsboro, respectively. The recommended cultivars based on this 1-year study are Florida Radiance, Benicia, and Camino Real for June-bearing cultivars, and Albion and San Andreas for day-neutral cultivars.

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Locally produced strawberries (Fragaria ×ananassa) have outstanding market potential. But strawberry production has been decreasing in the north-central United States, partly because of high production risks associated with the traditional matted-row system. The annual plasticulture system attracts attention but its low yield limits the wide adoption of the production system in the north-central United States. High tunnels are widely used to extend strawberry seasons worldwide, but the system was not fully explored in the United States. Although the benefits of growing strawberries in high tunnels were recognized, information on suitable strawberry cultivars specific for the fall-planted high tunnel production system is limited. A wide range of short-day and day-neutral strawberry cultivars, including recently released cultivars, were evaluated in the fall-planted annual plasticulture high tunnel systems for three seasons. Averaged among cultivars, the marketable yields were 1.96, 1.35, and 2.27 lb/plant for 2015–16, 2019–20, and 2020–21 seasons, respectively. The combined use of high tunnels and floating rowcovers created favorable microclimate conditions that led to high yields. Florida Radiance, San Andreas, Chandler, and Rocco were the top-yielding cultivars. Besides Chandler, the other top-yielding cultivars entered peak harvest in the second half of April. Harvests ended at the end of May or early June. All cultivars reached the US Department of Agriculture standard for total soluble solids in all three seasons, although Camino Real, FL Radiance, and Sweet Sensation consistently had relatively lower sugar content. Considering a warm-season crop could grow in high tunnels before or after strawberry, a diversified cropping system involving strawberry and other vegetables is highly valuable for high tunnel production systems in the north-central United States. This study did not compare cultivars’ resistance to diseases, but it should be a critical factor in selecting cultivars. Future studies are also warranted to evaluate the effects of incorporating soil treatments and cover cropping for suppressing diseases in the soil-based high tunnel system. Sustainable management strategies to control two-spotted spider mites (Tetranychus urticae) are also crucial in successfully using the system in the north-central United States.

Open Access

Healthy transplants are critical to productivity in the field. For certified organic production in the United States, seedlings must be grown in media that meet the standards of the US Department of Agriculture’s National Organic Program. Many commercial organic media options are available, they vary substantially in composition, and it is unknown to what extent this influences seedling performance. This project compared tomato (Solanum lycopersicum L.) seedling emergence and growth in seven commercially available media for organic production and evaluated posttransplant performance. Tomato seedlings were grown in greenhouses at Wanatah, West Lafayette, and Vincennes, IN, USA. Chemical characteristics of the media measured in saturated media extract ranged as follows: pH 5.2–7.5; electrical conductivity (EC) 0.79–4.68 dS·m−1; 1–332 ppm nitrate-nitrogen, 5–69 ppm phosphorus, 41–451 ppm potassium, 78–714 ppm calcium, and 25–121 ppm magnesium. Higher media EC was associated with slower and less uniform seedling emergence and reduced total emergence. Seedling aboveground dry weights were significantly greater in media that contained compost. Relative performance in media containing compost varied across trials. The aboveground dry weight of tomato seedlings 4 weeks after transplanting did not differ for seedlings started in the five compost-based media, and those plants were significantly larger than plants started in the two media without compost. Larger plants tended to flower and set fruit earlier. Media testing protocols that predict nutrient supply over the production cycle could likely improve management in organic transplant production.

Open Access

Cucumber (Cucumis sativus) is one of the most important vegetables produced and consumed in the United States. In the midwestern United States, a major obstacle to spring cucumber production is low soil temperatures during plant establishment. High tunnel is a popular tool for season extension of vegetable production. Low soil temperature is a challenge for cucumber production even inside high tunnels. Grafting is a cultural practice known to help control soilborne diseases and improve plants’ tolerance to abiotic stresses. Recent studies found that using grafted cucumber plants with cold-tolerant rootstocks greatly benefited early-season seedless cucumber production in high tunnels. The objective of this study was to analyze the economic feasibility of growing grafted cucumber in high tunnels. A comparison of partial costs and returns between growing grafted and nongrafted cucumbers in a high tunnel in Vincennes, IN, was conducted. Data were used to develop a partial budget analysis and sensitivity tests. Data included production costs, marketable yield, and price of cucumber through different market channels. This study provided a baseline reference for growers interested in grafting seedless cucumber and for high tunnel production. Although costs of grafted transplants were higher, their yield and potential revenue helped to offset the higher costs. Results indicated that grafting can help farmers increase net returns through the increasing yield of grafted plants. Results from the sensitivity analysis illustrated how the increased yield of grafted cucumbers offsets the extra cost incurred in the technique while providing a higher revenue. While actual production costs for individual farmers may vary, our findings suggested that grafting can be an economically feasible tool for high tunnel seedless cucumber production.

Open Access

Seedless cucumber (Cucumis sativus) is a popular and high-value crop found in many local food markets. Worldwide, it is the third most important high tunnel crop after tomato (Solanum lycopersicum) and pepper (Capsicum annuum). One challenge of growing seedless cucumbers in high tunnels is low soil temperatures in the early season that suppress plant growth even when air temperatures would be adequate. Grafting cucumbers to enhance crop tolerance to suboptimal temperature stresses has been widely used in Asian countries. However, little information is available in the United States about graft compatibility, cold hardiness, and seasonal extension potential of growing grafted seedless cucumbers in high tunnels. In this study, we tested the effects of grafting with two winter squash (Cucurbita moschata) rootstocks (‘Titan’ and ‘Marvel’) on vegetative growth and yield of three seedless cucumbers (‘Excelsior’ pickling cucumber, ‘Socrates’ Beit Alpha cucumber, and ‘Taurus’ long-type cucumber) in the spring seasons of 2016 and 2017 in high tunnels located in U.S. Department of Agriculture (USDA) hardiness zone 6. Nongrafted plants were included as controls. All grafted plants survived the suboptimal temperature stress during transplant period, whereas 59% of nongrafted plants died in the 2016 season. Irrespective of rootstock and cucumber cultivar, vine growth rates of nongrafted cucumbers in April of both years were lower than those of the grafted crops. Cucumber cultivars Excelsior and Taurus grafted onto Marvel winter squash rootstock had higher yields in May 2016 compared with the yields of the nongrafted plants in the same month. The enhanced early-season yields of grafted plants were observed on cucumber cultivars Excelsior and Socrates in 2017 regardless of rootstocks. Grafting also increased the entire season’s yields of the three cucumber cultivars in 2017, but not in 2016. More comprehensive evaluations about cold tolerances of newly released cucumber rootstocks are needed. Further studies are also warranted to improve our understanding of effects of rootstock and scion interactions on cucumber growth and yield in high tunnel production.

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Interest in producing specialty melons (Cucumis melo) is increasing in Florida, but information on yield performance, fruit quality, and disease resistance of specialty melon cultivars grown in Florida conditions is limited. In this study conducted at Citra, FL, during the 2011 Spring season, 10 specialty melon cultivars were evaluated, in both certified organic and conventionally managed fields, including: Creme de la Creme and San Juan ananas melon (C. melo var. reticulatus), Brilliant and Camposol canary melon (C. melo var. inodorus), Ginkaku and Sun Jewel asian melon (C. melo var. makuwa), Arava and Diplomat galia melon (C. melo var. reticulatus), and Honey Pearl and Honey Yellow honeydew melon (C. melo var. inodorus). ‘Athena’ cantaloupe (C. melo var. reticulatus) was included as a control. ‘Sun Jewel’, ‘Diplomat’, ‘Honey Yellow’, and ‘Honey Pearl’ were early maturing cultivars that were harvested 10 days earlier than ‘Athena’. ‘Athena’ had the highest marketable yield in the conventional field (10.7 kg/plant), but the yield of ‘Camposol’, ‘Ginkaku’, ‘Honey Yellow’, and ‘Honey Pearl’ did not differ significantly from ‘Athena’. Under organic production, ‘Camposol’ showed a significantly higher marketable yield (8.3 kg/plant) than ‘Athena’ (6.8 kg/plant). ‘Ginkaku’ produced the largest fruit number per plant in both organic (10 fruit/plant) and conventional fields (12 fruit/plant) with smaller fruit size compared with other melon cultivars. Overall, the specialty melon cultivars, except for asian melon, did not differ significantly from ‘Athena’ in terms of marketable fruit number per plant. ‘Sun Jewel’, ‘Diplomat’, and ‘San Juan’ showed relatively high percentages of cull fruit. ‘Honey Yellow’, ‘Honey Pearl’, and ‘Sun Jewel’ exhibited higher soluble solids concentration (SSC) than ‘Athena’ in both organic and conventional fields, while ‘Brilliant’, ‘San Juan’, and ‘Ginkaku’ also had higher SSC than ‘Athena’ under organic production. ‘Honey Yellow’, ‘Sun Jewel’, ‘Brilliant’, and ‘Camposol’ were less affected by powdery mildew (caused by Podosphaera xanthii) and downy mildew (caused by Pseudoperonospora cubensis) in the conventional field. ‘Honey Yellow’ and ‘Camposol’ also had significantly lower aboveground disease severity ratings in the organic field compared with ‘Athena’, although the root-knot nematode (RKN) (Meloidogyne sp.) gall rating was higher in ‘Honey Yellow’ than ‘Athena’.

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Fresh-consumed parthenocarpic cucumbers (Cucumis sativus) are a popular and high-value crop sold in local food markets. The parthenocarpic plant characteristics and climbing growth habit make cucumbers an ideal crop for high-tunnel production. Major types of parthenocarpic cucumbers include Beit alpha and mini, Dutch greenhouse, American slicer, and Japanese. Information regarding yield performance, plant growth, and disease resistance of the four types grown in high-tunnel conditions is limited. In this study, 16 parthenocarpic cucumber cultivars from the four major types were evaluated in high tunnels at three locations in Indiana and Illinois during Spring 2018. Plants were pruned to a single stem that was supported on a string. At all locations, the cultivars that had the most total yields were Beit alpha and mini, although their total yields were not always significantly higher than that of all the others. However, Beit alpha and mini cucumbers had high percentages of unmarketable fruit, mainly because of insect feeding damage and mechanical injuries on the skins that led to scarred fruit. Dutch greenhouse cultivars had relatively lower marketable yields at two of the three locations where there was a high percentage of misshaped fruit. ‘Tasty Green’ Japanese cucumber consistently had the lowest yields at all three locations. This cultivar also produced the most side shoot growth and, therefore, more pruning waste. The Japanese types ‘Tasty Jade’ and ‘Taurus’ had yields comparable to those of other cultivars, and they were more tolerant to two-spotted spider mites (Tetranychus urticae). However, ‘Tasty Jade’ was the cultivar most susceptible to powdery mildew (Podosphaera xanthii and Golovinomyces cichoracearum). ‘Corinto’ American slicer cucumber had relatively high yields at two of the three locations. This cultivar also had the highest percentage of marketable fruit. Information provided in the study is readily useful for growers using high tunnels when selecting parthenocarpic cucumber cultivars. It is also valuable for seed companies wishing to breed new cultivars adaptive for high-tunnel production.

Open Access