Location: Crop Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
1. Develop high yielding soybean germplasm with enhanced seed composition and plant protection traits for soybean production system of the mid-south United States; 2. Identify the physiological mechanisms that regulate seed composition qualities of oil, fatty acids, and protein under stress environment; 3. Optimize Early Soybean Production Systems (ESPS) and pest management strategies for the mid-south United States; and 4. Coordinate and participate in the Uniform Soybean Test - Southern States.
1b. Approach (from AD-416):
Use publicly available genetic diversity in soybean germplasm, including fatty acid mutants, phytic acid mutants and Plant Introductions from USDA collections, to develop germplasm with modified fatty acid and phytic acid levels which are adapted to the mid-south; use publicly available genetic diversity and known charcoal rot resistant lines to improve charcoal rot resistance in germplasm with high yield potential for the mid-south; develop high-yielding agronomically superior lines with adaptation to Early Soybean Production System (ESPS) using available genetic diversity from both northern and southern USA lines; determine the effects of nutrient uptake and assimilation on oil, fatty acids, and protein production in seed under drought; measure the effects of drought and heat stress on nutrient uptake and assimilation on oil, fatty acids, and protein production in seed; determine optimum plant density and row spacing for cultivars of different maturities and plant architecture adapted to ESPS for yield or fungicide deposition; relate optimum population to light interception; determine optimum seeding rate for late plantings; evaluate planting date effect on soybean rust infection; determine effect of late season insecticide application on yield; coordinate, analyze data, and publish the annual reports of the Uniform Soybean Tests – Southern States.
3. Progress Report:
The research program of this project focused on the measurement and analysis of seed composition traits as affected by biotic and abiotic environmental conditions and the development of soybean germplasm with improved seed composition. Additionally, this project was responsible for the Uniform Soybean Tests, Southern States. The research project focused on two components: 1) breeding for mid-oleic acid, low linolenic acid and low phytic acid soybean lines, and 2) the effect of biotic (including charcoal rot and Phomopsis seed decay) and abiotic (including drought and heat) stresses on soybean seed composition in the Midsouth, especially in the Early Soybean Production System. One major accomplishment was the quantification of the effect of maturity genes, temperature, genotypic background, and their interactions on seed constituents, germination and seed vigor. These effects were estimated in two sets of near-isogenic soybean lines which varied for maturity genes. This approach allowed quantification of the partial contribution of each factor (maturity genes, temperature, genetic background, and their interactions). This was the first report on quantifying the partial contribution of maturity, temperature, genetic background, and their interactions to the total variability for seed protein, oil, sugars, and mineral nutrients using near-isogeneic lines for maturity genes under the Early Soybean Production System. The data support that later maturities may favor protein production and earlier maturities may favor oil production, but it depends on the genotype, temperature, and the year. The results also support the view that Phomposis seed decay is a major cause of poor seed germination in Mississippi. Low linolenic lines were evaluated for yield, agronomics and low linolenic acid. Ten low linolenic lines are in multi-location field trials and 82 lines are in preliminary yield trials in 2013. Work advanced to introgress reduced phytate into lines adapted to the Midsouth using single crosses, backcrosses and molecular markers. Lines were evaluated for low linolenic acid in single cross and backcross populations. Molecular markers were used to select individuals from lines with high yield or important agronomic traits in the preliminary yield trials that will breed true for low linolenic acid or low phytate. Three low phytate lines are in multi-location field trials and 23 lines are in preliminary yield trials in 2013. The mid-oleic acid project was switched to a high oleic acid goal in 2010. The statistical analysis and data presentation for the Uniform Tests were revised and updated, and additional agronomic data were collected and presented in the annual report. The effort to coordinate the tests was completed each year of the project and continues in the new project plan. The results of this research provided growers and other scientists information regarding the effects of biotic (charcoal rot and Phomopsis) and abiotic (drought and heat) on seed composition. These and other results of the research program resulted in 23 scientific publications over the 5 years of the project.
1. Effects of soybean diseases on seed composition in relation to irrigation. Charcoal rot and Phomopsis seed decay (PSD) are soybean diseases that cause yield loss and/or poor seed quality, especially under conditions of the Early Soybean Production System. ARS scientists at Stoneville, MS, evaluated the effect of charcoal rot and PSD on seed composition (protein, oil, fatty acids, sugars, minerals, and isoflavones) under irrigated and non-irrigated conditions. Seed composition components were significantly affected by irrigation treatment (irrigated or non-irrigated) and disease (charcoal rot or PSD). The degree of the effect on seed composition depended on the level of resistance inherent in the soybean genotype evaluated. Results emphasize the importance of irrigation management and the need for soybean varietal selection to maintain high seed nutritional qualities. Information from this study is valuable for breeders when selecting for seed composition traits under drought and disease pressure.
2. Soybean seed protein, oil, fatty acids, and isoflavones are altered by potassium fertilizer rates. Potassium is an essential nutrient for crop yield and seed quality, and its deficiency in soils can result in yield loss and reduction in seed quality. ARS scientists at Stoneville, MS, investigated the effect of potassium fertilizer rates on seed protein, oil, fatty acids, and isoflavones. The results of a three-year experiment with five rates of potassium indicated that increasing the potassium fertilizer rate did not result in consistent effects on yield. However, increasing potassium rate increased protein, oleic acid, and total isoflavone concentrations at two locations in two of the three years. The research demonstrated the feasibility of obtaining desirable seed constituents by optimizing potassium fertilizer management.
Bellaloui, N., Yin, X., Mengistu, A., Mcclure, A.M., Tyler, D.D., Reddy, K.N. 2013. Soybean seed protein, oil, fatty acids, and isoflavones altered by potassium fertilizer rates in the midsouth. American Journal of Plant Sciences. 4(5):976-988.