Date of Award

5-2013

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Annette L. Wszelaki

Committee Members

David M. Butler, Dennis E. Deyton, Jerome F. Grant

Abstract

High tunnels extend the production season, and increase fruit quality, yield and crop marketability of high-value crops, but have been underutilized in the Southeast. In this study, organically managed variety trials of two high-value crops, strawberry (Fragaria x ananassa) and tomato (Solanum lycopersicum), were conducted in high tunnel (HT) and open field (OF) production systems to compare yield and quality. Furthermore, specialty crops are commonly grown on black plastic mulch to increase earliness of harvest, fruit quality and yield. However, plastic disposal is time consuming and costly. Degradable mulches reduce removal costs, lessen environmental impacts, and provide functionality during the season. Degradable alternatives to black plastic mulch were compared in HTs and the OF to measure degradability in the production season, weed control, and tomato yield.

Yield, size, firmness, color, soluble solids content, titratable acidity, and the ratio of soluble solids content to titratable acidity were evaluated for six strawberry cultivars. These were compared among winter HT, spring HT, and spring OF production systems. Quality was highest in the winter HT system but yields were lowest. The spring OF system produced higher yields, but quality was reduced. Albion attained the best quality among cultivars, while Strawberry Festival produced the highest marketable yield (weight and number of fruit).

A comparison of yield and quality of four tomato cultivars grown in HT and OF systems showed that HTs increased yields compared to the OF. Early Girl had greater yields than the other three cultivars, and Cherokee Purple (CP) had the lowest yields. While lower than other cultivars, CP yields were three times greater in the HT versus the OF production system, and price premiums attained for organic heirlooms can help offset yield differences.

Four degradable mulches (BioAgri, BioTelo, WeedGuardPlus, and an experimental spunbond nonwoven fabric (SB-PLA)) were compared with black plastic and a bare ground control for yield, weed control, and degradability in HT versus OF production systems. WeedGuardPlus, BioAgri and BioTelo performed comparably to black plastic with regard to yield and weed control, while degrading during the production season to potentially provide a more sustainable alternative for specialty crop production.

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