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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF SOYBEAN GENEOTYPES AND MANAGEMENT SYSTEMS FOR EARLY SEASON AND STRESS ENVIRONMENTS Title: Irrigation management: effects of soybean diseases on seed composition in genotypes differing in their disease resistance under irrigated and nonirrigated conditions

Authors
item Bellaloui, Nacer
item Mengistu, Alemu
item Fisher, Daniel
item Zobiole, Luiz -
item Abbas, Hamed

Submitted to: Nova Hedwigia
Publication Type: Book / Chapter
Publication Acceptance Date: April 21, 2012
Publication Date: December 20, 2012
Citation: Bellaloui, N., Mengistu, A., Fisher, D.K., Zobiole, L.H., Abbas, H.K. 2012. Irrigation management: effects of soybean diseases on seed composition in genotypes differing in their disease resistance under irrigated and nonirrigated conditions. Nova Hedwigia. 1:1-42.

Interpretive Summary: Charcoal rot is a soybean disease that causes yield loss and poor seed quality, especially under drought conditions of the Early Soybean Production System. Phomopsis is also one of the major soybean seed decay pathogens, resulting in poor seed quality, especially under humid, warm conditions as in the Early Soybean production System. Since the disease infection is influenced by irrigation management, and since there are no commercial soybean cultivars resistant to either charcoal rot or phomopsis, irrigation management to minimize charcoal rot and phomopsis to maintain high seed quality is crucial. Therefore, the objective of this research was to evaluate the effect of charcoal rot and phomopsis on seed composition (protein, oil, fatty acids, sugars, minerals, and isoflavones) under irrigated and nonirrigated conditions in the early Soybean production System. Two-year field experiments were conducted using soybean genotypes susceptible and moderately resistant to charcoal rot and phomopsis. Our research demonstrated that seed composition were significantly affected by irrigation treatment (irrigated or nonirrigated), disease (charcoal rot or phomopsis), and the degree of effect in seed composition depended on the level of resistance of the variety to the disease. The research emphasizes the significance of irrigation management and the need for soybean varietal selection to maintain high seed nutritional qualities. The higher levels of calcium, potassium, boron in seed of moderately resistant variety to charcoal rot or phomopsis suggest that these minerals may be associated with disease infection. Information in this study is valuable to breeders to select for seed composition traits under drought and diseases. Irrigation techniques provided in this research are useful to growers to make decision about when to irrigate and how to make irrigation more efficiently.

Technical Abstract: Soybean seed is a major source of protein and oil in the world. Nutritional qualities of soybean seed are determined by the quantity and quality of seed composition components (protein, oil, fatty acids, isoflavones, and minerals). Charcoal rot is a disease caused by the fungus Macrophomina phaseolina (Tassi) Goid and results in yield loss and poor seed quality, especially under drought conditions. Phomopsis, caused by Phomopsis longicolla Hobbs, is also one of the major soybean seed decay pathogens, resulting in poor seed quality, especially under humid, warm conditions. Disease infection is influenced by irrigation management. Since there are no commercial soybean cultivars resistant to either charcoal rot or Phomopsis, irrigation management to minimize charcoal rot and phomopsis infection to maintain high seed quality is crucial. Therefore, the objective of this research was to evaluate the effect of charcoal rot and Phomopsis on seed protein, oil, fatty acids, sugars, minerals, and isoflavones under irrigated (IR) and nonirrigated (NIR) conditions. Field experiments were conducted using soybean genotypes susceptible (S) and moderately resistant (MR) to charcoal rot and Phomopsis. This research evaluates the effect of charcoal rot on seed composition by infesting the soil with charcoal rot (infested soil conditions, INF) or control (noninfested soil conditions, NINF). The effects of Phomopsis on seed composition were achieved by infecting soybean plants and assessing seed composition components at harvest maturity and 15 days after harvest maturity. Our research demonstrated that seed composition components were significantly altered by irrigation treatment (IR or NIR), disease (charcoal rot or Phomopsis), and the degree of alteration of these components depended on the level of resistance of the genotype to the disease. The research highlights the significance of irrigation management and soybean varietal selection in maintaining high seed nutritional qualities. Special section will be devoted to soybean irrigation and current irrigation techniques.

Last Modified: 11/21/2014
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