Adult Plant Evaluation of Soybean Accessions for Resistance to Phakopsora pachyrhizi in the Field and Greenhouse in Paraguay

• Published in: Plant disease Vol. 92; no. 1; pp. 96 - 105
• Main Authors: Miles, M.R, Morel, W, Ray, J.D, Smith, J.R, Frederick, R.D, Hartman, G.L
• Format: Journal Article
• Language: English
• Published: United States 2008
• Subjects: cultivars; disease resistance; disease severity; field experimentation; genetic resistance; genetic variation; genotype; germplasm screening; Glycine max; greenhouse experimentation; maturity groups; Phakopsora pachyrhizi; plant genetic resources; plant pathogenic fungi; rust diseases; soybeans; sporulation; Paraguay
• ISSN: 0191-2917; 1943-7692
• DOI: 10.1094/pdis-92-1-0096

Five hundred thirty soybean accessions from maturity groups (MG) III through IX were evaluated for resistance to Phakopsora pachyrhizi in a replicated field trial at Centro Regional de Investigación Agrícola in Capitán Miranda, Itapúa, Paraguay during the 2005-06 season. Soybean rust severities of individual accessions ranged from 0% (resistant) to 30.0% (susceptible). In MG III and IV, the most resistant accessions were PI 506863, PI 567341, and PI 567351B, with severities less than 1.2%. In MG V, the most resistant accessions were PI 181456, PI 398288, PI 404134B, and PI 507305, with severities less than 0.3%. In MG VI, the most resistant accessions were PI 587886, PI 587880A, and PI 587880B, with severities less than 0.3%. In MG VII and VIII, the most resistant were PI 587905 and PI 605779E, with severities less than 1.0%. In MG IX, the most resistant accessions were PI 594754, PI 605833, PI 576102B, and PI 567104B, with severities less than 1.0%. The resistance in 10 selected accessions from MG VI, VII, VIII, and XI was confirmed in subsequent greenhouse and field experiments where severities of 0.4% or less and reddish-brown lesions with sporulation levels less than 3.0 were observed. These accessions, with low severities in the adult plant field evaluation, may be new sources of resistance to P. pachyrhizi.