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Photosynthetic Consequences of Late Leaf Spot Differ between Two Peanut Cultivars with Variable Levels of Resistance
Author(s) -
Singh Maninder P.,
Erickson John E.,
Boote Kenneth J.,
Tillman Barry L.,
Bruggen Ariena H.C.,
Jones James W.
Publication year - 2011
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2011.03.0144
Subject(s) - cultivar , biology , leaf spot , arachis hypogaea , photosynthesis , lesion , horticulture , plant disease resistance , agronomy , botany , gene , psychology , biochemistry , psychiatry
Late leaf spot (LLS) caused by Cercosporidium personatum (Berk. & Curt.) Deighton reduces leaf CO 2 assimilation rate ( A sat ) and accelerates leaf defoliation, which together lead to major reductions in peanut ( Arachis hypogaea L.) yield worldwide. This study was conducted to determine whether differences in photosynthetic response to LLS severity exist among peanut cultivars of differing resistance. Field experiments were conducted in 2008 and 2009 to study the effects of LLS on A sat of tagged leaf cohorts, and photosynthetic response of similar age leaves to LLS in peanut cultivars with more (York) and less (Carver) quantitative resistance. A nonlinear model, y = (1 − x ) β was used to analyze A sat data, where y is relative A sat , x is measured visual lesion area, and β represents the relationship between virtual and visual lesion area. Progression of LLS severity on leaf cohorts was slower in York than in Carver. However, the reduction in A sat with leaf cohort age was similar across the cultivars. This paradox could be explained by a higher β value in York (4.6) than in Carver (3.6), indicating a greater relative reduction in A sat beyond the necrotic lesion area in York. This greater reduction in A sat in York compared to Carver was most closely related to a reduction in maximum carboxylation velocity. Results indicated that future efforts to improve LLS resistance should include sustaining A sat in response to LLS infection along with slower disease progress.