Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Master of Science in Horticulture (MS)

Degree Level

Graduate

Department

Horticulture

Advisor/Mentor

Garcia, Maria E.

Committee Member

Threlfall, Renee T.

Second Committee Member

McWhirt, Amanda L.

Third Committee Member

Lee, Jacquelyn A.

Keywords

Cultivars; Decay; Fruit quality; High tunnels; Storage; Table grapes

Abstract

Table Grapes (Vitus vinifera) are highly valued horticulture crops world-wide. Often, table grape production in the southern United States is restricted due to climate and pest issues. Viticulture production could be expanded to this region by the use of controlled environment growing systems, such as high tunnels (HT). The objective of this project was to evaluate the effectiveness of HT systems for grape cultivation and compare the effects of different cluster thinning treatments on vines. In this two-year study, the cultivars Faith, Gratitude, Hope, and Jupiter were grown in HT systems and assessed for postharvest qualities at harvest and during storage. For this research, the table grapes were grown on a Geneva Double Curtain trellis system in two HT systems (University of Arkansas Agricultural Research and Extension Center, Fayetteville and a private farm in Cabot) in Arkansas (USDA hardiness zones 7a and 7b). In Fayetteville, two cluster thinning treatments: none (Trt 1) and pea-sized berry (Trt 2) were applied to the vines. In Cabot, three cluster thinning treatments: none (Trt 1), pea-sized berry (Trt 2), and veraison (Trt 3) were applied to the vines. Four kg of grapes were harvested from each location in July 2018 and August 2019. For each location, two clusters were placed in a 0.9 kg vented clamshell in triplicate for composition and marketability analyses. Fruit was evaluated for composition at harvest and marketability attributes during storage (0, 7, 14, and 21 days) at 2 °C. Two clusters per clamshell were evaluated in triplicate for physiochemical attributes (berry weights and texture), marketability attributes (decay, and berry drop), color (L*, chroma, and hue), and organic acids and sugars (HPLC). These cultivars differed in post-harvest characteristics. The cultivar Jupiter exhibited large berry size, high ratios of sugars to acids, but had high levels of berry drop. The cultivar Gratitude had firm berries with rich coloration. ‘Faith’ had the highest decay levels and a dullest color saturation, which diminished further during storage. ‘Hope’ had low decay and rich coloration. In both locations, decay increased during storage for all cultivars. Cluster thinning at both sites appeared to have minimal impact, indicating that this practice may not be necessary for high-tunnel grown table grapes. Based on these observations, high tunnel technology may be a feasible option for producing high quality table grapes.

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