Final report for GS22-272
Project Information
Demand in the United States for vegetable soybean or edamame (Glycine max (L.) Merr.) has increased over the past two decades owing to its excellent nutritional value and health benefits. It has become the second largest soyfood consumed in the US (25,000-30,000 tons annually). Domestic edamame production is limited in the US, and at least 70% of the edamame consumed is imported. Poor seed germination and seedling emergence reduces yield and is one of the major production problems in the US. This proposal seeks to identify effective organic and conventional seed treatments to improve edamame emergence under field situations. Our system will assess effects of organic seed treatments to enhance seedling emergence and vigor and sustainably control soilborne diseases. The proposed study will have a strong impact on the edamame supply chain by: 1. improving edamame emergence and resulting yields; 2. improving the sustainability of crop production for low input and organic producers by providing alternative management strategies free of synthetic pesticides. Overall, this research will benefit producers by strengthening and diversifying agricultural economies in local and regional markets in the mid-Atlantic region. The findings of this research will be disseminated to researchers, growers, extension agents, and the seed and seed treatment companies through publications, presentations, field days, and workshops.
The goal of the proposed project is to identify efficacious organic seed treatments to improve edamame emergence and stand establishment. Current commercial biological seed treatments will be tested for their effects on edamame seedling growth promotion and/or disease control. The goals will be achieved with two studies assessing (1) Growth promoting novel organic seed treatments for their ability to improve total emergence percentage, mean time to emergence; and (2) assessing efficacy of organic seed treatments on edamame seeds against multiple soilborne diseases. Soybean sudden death syndrome (SDS) causing by Fusarium virguliforme, seedling blight and root rot causing by Rhizoctonia solani, seedling damp-off causing by Pythium sp., and southern stem rot caused by Sclerotium rolfsii are the common soil-borne diseases that kill and rot seeds before germination or cause seedling death.
Cooperators
Research
Seeds of two edamame cultivars were used in field trials in 2024 and 2025. These were treated with various seed treatments to determine the effects against several economically important soilborne diseases (e.g., Rhizoctonia solani, Pythium sp., and Sclerotium rolfsii) as well as their growth-promoting effects on edamame seedling growth. Trichoderma harzianum (ROOTSHIELD® WP, BioWorks, USA), a commercial plant beneficial species and a conventional fungicide product (VIBRANCE® TRIO, Syngenta, USA) were used as experimental treatments. Nontreated controls were also incorporated into the trials. Treatments were either treated or not treated with Bradyrhizobium japonicum (Exceed Soybean Inoculant, Visjon Biologics).
A completely randomized block design with four replications per treatment were used in these trials, which were planted in fields with a history of soybean production and poor stand emergence. Seeds of the cultivars VT-Sweet and Kirksey were used in these trials. Each cultivar had a separate trial with 6 different seed treatments. Rootshield and Vibrance Trio treatments were conducted by Syngenta Crop Protection. Treatment with Exceed inoculant were conducted according to labeled instructions.
A total of 8 field trials were conducted in 2024 and 2025 to examine the effects of seed treatments on edamame emergence (2 in each year/per cultivar). Each individual plot consisted of two rows (spaced 2 ft. apart) and 25 ft in length (50 row-ft.) and were planted with 100 seed total (50 seed per row) at a depth of 1 inch. Trials were managed according to Virginia Cooperative Extension in terms of pest control. Stand counts (number of emerged plants) were counted every 4 days after emergence began for a total of 4 weeks. Plots were also monitored for any post-emergence damping off diseases during this period. At the final stand count, 5 random plants per row were measured for plant height.
Data were analyzed using Agricultural Research Manager (ARM, GDM Solutions, Brookings, South Dakota). Analysis of variance was conducted to determine significant differences (p<0.05) in stand counts and plant height measurements. Means separations were determined using Fisher's LSD.
Significant differences in stand counts were discovered in all trials conducted. The below table summarizes these results by cultivar and year. The two trials for each year/cultivar combination were able to be analyzed across the two trials annually. For both years and cultivar, Exceed Soybean Inoculant and Rootshield were not able to provide a significant increase when compared to the nontreated control in % germinated seedlings at the final stand count for any scenario. Vibrance Trio, a conventional fungicide seed treatment, did provide significantly increased stands when compared to the nontreated control and Rootshield treated plots. The addition of Exceed to Vibrance Trio did not significantly improve stand. No differences in plant height measurement at the final stand count were detected in any year/cultivar/trial combinations (data not shown).
| % Seed Germination | ||||
| 2024 | 2025 | |||
| Treatment | VT-Sweet | Kirksey | VT-Sweet | Kirksey |
| Nontreated | 70.5 a | 65.8 a | 75.3 a | 67.1 a |
| Exceed Only | 68.8 a | 66.3 a | 77.3 a | 66.6 a |
| Vibrance Trio | 81.7 b | 75.5 b | 83.0 b | 80.8 b |
| Vibrance + Exceed | 82.3 b | 74.8 b | 83.3 b | 79.5 b |
| Rootshield | 73.0 a | 64.8 a | 74. 5 a | 70.0 a |
| Rootshield + Exceed | 71.1 a | 66.0 a | 78.8 a | 68.8 a |
The OMRI-approved treatments of Rootshield and Exceed did not improve edamame seedling germination or plant vigor in these studies. Further studies need to examine other treatments that may be effective at improving stands.
Educational & Outreach Activities
Participation summary:
Not available.
Project Outcomes
Not available.