Response of the Edamame Germplasm to Early-Season Diseases in the United States

Edamame (Glycine max (L.) Merr.) is a specialty soybean newly grown in the United States that has become the second most widely consumed soy food (25,000–30,000 tons annually). Poor crop establishment caused by soilborne diseases is a major problem limiting edamame production in the U.S. This study investigated 24 edamame cultivars/lines to determine their response to three soilborne pathogens causing seed rot and seedling damping off, including Rhizoctonia solani, Sclerotium rolfsii, Pythium irregulare, and Xanthomonas campestris pv. glycines, a seedborne pathogen that caused severe outbreaks of bacterial leaf pustules in mid-Atlantic regions in 2021. The hypothesis was that resistant variations existed among the genotypes, which could be used for production and future breeding efforts. The results reveal that all genotypes were affected, but partially resistant varieties could be clearly recognized by a significantly lower disease index (p < 0.05), and no genotype was resistant to all four diseases. Newly developed breeding lines showed overall higher disease resistance than commercial cultivars, particularly to R. solani and P. irregulare. This study found genetic variability in edamame, which can be helpful in breeding for resistance or tolerance to early-season diseases. The result will promote domestic edamame production and further strengthen and diversify agricultural economies in the U.S.