Date of Graduation

12-2015

Document Type

Thesis

Degree Name

Master of Science in Plant Pathology (MS)

Degree Level

Graduate

Department

Plant Pathology

Advisor

Terry Kirpatrick

Committee Member

John Rupe

Second Committee Member

Robert Robbins

Third Committee Member

Pengyin Chen

Fourth Committee Member

Navaam Hettiarachchy

Keywords

Biological sciences; Arkansas; Heterodera; Meloidogyne; Nematodes; Soybean

Abstract

Edamame (Glycine max), also known as vegetable soybean, was introduced to the United States from Japan in 1890 and has been growing in popularity as a nutrient-rich, low-sugar snack in recent years. In 2012, the American Vegetable Soybean and Edamame, Inc. established the first domestic commercial processing plant in Mulberry, Arkansas and contracted local growers for production. Since the crop is harvested when seed are immature, management practices are different from those for traditional soybean. Plant-parasitic nematodes, particularly Meloidogyne incognita (southern root-knot) and Heterodera glycines (soybean cyst), are common in Arkansas and are pests of concern for edamame growers. Edamame production fields in central Arkansas were sampled in 2013 and 2014 immediately after harvest to determine the identity, incidence, and population density of nematodes. The most common plant parasitic nematode genera were Meloidogyne spp, Heterodera glycines, and Pratylenchus spp in both years. From the collected Meloidogyne populations, only M. incognita was identified in both years of the survey. Concrete microplots were used to evaluate the impact of a range of initial population densities of both M. incognita and H. glycines. Although results were variable, increasing initial nematode populations tended to result in decreased yield. Neither nematode species impacted food quality traits including lipid, starch, or total sugar content, but H. glycines suppressed seed protein levels at the highest studied population density. Edamame breeding lines from the University of Arkansas Division of Agriculture soybean breeding program were evaluated for host suitability to M. incognita race 3 and H. glycines race 3 in greenhouse trials. Four lines appeared to be poor hosts for M. incognita in comparison to all other lines in test. All lines were suitable hosts for the H. glycines populations in this study. Results of the study will aid local producers and crop advisors on an insight on the potential risk of root-knot and soybean cyst nematodes to this emerging crop. Studies on the interactions of parasitic nematodes on the quality and quantity of vegetable soybean is a novel perspective that will enhance nematode management strategies for edamame production and expansion.

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