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Vegetable soybean, also known as edamame, has become increasingly popular in the United States due to its excellent nutrition and health benefits. This rising demand has sparked the interest of local farmers in growing edamame. However, a significant problem in edamame production is the poor seedling emergence. This dissertation focuses on three key objectives: 1) exploring the physiological traits linked to the low emergence of edamame seeds; 2) enhancing edamame seedling emergence by identifying genotypes with high vigor and resistance to soil-borne diseases; and 3) determining the optimal temperature for edamame seedling emergence. The study includes newly developed edamame breeding lines from the soybean breeding programs at Virginia Tech and the University of Arkansas, and major edamame cultivars commonly used in the Mid-Atlantic region. The results have identified several genotypes that exhibit high seeding vigor, aging tolerance, and consistently achieve a plant stand of over 80% in both laboratory and field conditions. It is also clarified that edamame's larger seed size leads to lower germination rates and slower emergence, although this is not correlated to total emergence. Moreover, environmental factors, pathogens and temperature, impact emergence. The study highlights that current edamame genotypes are commonly affected by soilborne pathogens, including Rhizoctonia solani, Athelia rolfsii, and Pythium irregulare, leading to seed rot and seedling damping off. However, the research has successfully identified partially resistant varieties characterized by significantly low disease indexes (p<0.05). Furthermore, the optimal temperature range for edamame seedling emergence (25-32°C) was found to be lower than that of other types of soybeans such as grain-type soybeans (29-36°C). This research provides a scientific foundation to improve edamame production practices. / Doctor of Philosophy / Vegetable soybean, also known as edamame, commonly consumed as a healthy snack, is steadily gaining popularity in the United States. However, there are significant challenges in achieving successful edamame plant growth from seeds. This research focuses on three primary objectives: first, understanding the underlying factors contributing to poor seedling emergence in edamame; second, identifying edamame genotypes with exceptional vigor and resistance to soil-borne diseases; and third, determining the ideal temperature conditions for optimal edamame seedling development. To accomplish these goals, a comprehensive study was conducted, encompassing various edamame varieties, including those developed by Virginia Tech and the University of Arkansas. The research identified some edamame genotypes that exhibited exceptional seed vigor, aging tolerance, and consistently achieved plant stands of over 80% under both laboratory and field conditions. Additionally, we also learned that bigger edamame seeds take longer time to grow, but the seed size does not affect the total emergence. Furthermore, we found that some diseases in the soil can hurt edamame seedlings, but we identified a few genotypes that are more resistant to these diseases. Lastly, in terms of temperature, we found that edamame seedlings grow the best between 25-32°C, which is slightly lower than other types of soybeans. Overall, this research helps farmers grow better edamame and brings more delicious and healthy food to our tables.

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The Mississippi River Valley Alluvial Aquifer (MRVAA) is declining precipitously due to irrigation withdrawal for row-crops. The development of scientific irrigation scheduling techniques and for soybean (Glycine max L.) will reduce withdrawal from the MRVAA. The objective of this research was to determine if soybean grain yield, irrigation water use efficiency (IWUE), and net return above irrigation cost could be optimized using a static irrigation threshold or if the irrigation threshold should be changed as a function of plant growth stage.

Field studies were conducted in 2003, 2004, and 2005 in the Mississippi delta at 12 locations across common production practices to evaluate the impact of 12 single applications of fungicides at the R3 and R5 growth stage on soybean yield, seed quality, and net returns. Averaged across locations, azoxystrobin alone and mixed with other fungicides increased yields 161 to 343 kg/ha compared to the nontreated control. Fungicide applications made at R3-R4 were more efficacious and resulted in larger yield increases than applications made at R5-R6. Plots treated at the R3-R4 growth stage with 0.11kg ai/ha azoxystrobin alone or in combination with other fungicides yielded 135 kg/ha more than plots treated with the same treatments at the R5-R6 growth stage. Azoxystrobin at 0.11 kg ai/ha and azoxystrobin at 0.11 kg ai/ha + 0.035 kg ai/ha diflubenzuron were the most profitable treatments and increased net returns $23/ha and $31/ha, respectively compared to the nontreated control.

Oils from soybeans and catfish by-products were extracted using hexane, propane, and supercritical carbon dioxide (SCCO2). Free fatty acids (FFA), peroxide values (PV), anisidine values (AnV), total oxidation (TOTOX), induction point (IP), iodine values (IV), and 2-thiobarbituric acid reactive substance (TBARS) were all measured to analyze oxidation of these oils. The extraction yield of propane, hexane, and SCCO2 oils was 80.4, 94.5, and 90%, in respect to total lipid content. Oils extracted with SCCO2 were more oxidized than those extracted with propane and hexane; probably due to the higher temperature and longer extraction time. The IP correlated with AnV, IV, PV, and TBARS for soybean and catfish oils. These results suggest that IP is the optimum way to measure soybean and catfish oil stability.