Variability in Growth Characteristics and Leafspot Resistance Parameters of Peanut Lines
1990
Knauft, D. A. | Gorbet, D. W.
Peanut (Arachis hypogaea L.) genotypes have been developed with varying levels of early and late leafspot [Cercospora arachidicola Hori and Cercosporidium personatum (Berk, and Curt.) Deighton] resistance. An understanding of the changes that occur during the growing season among resistance parameters and in vegetative and pod development will be beneficial to crop scientists. In this study, 16 genotypes were grown 30 cm apart within 90-cm rows and evaluated under disease pressure at 10-d intervals during a 2-yr period for disease rating, percentage leaf area necrotic, vegetative (V) stage, total vegetative weight, total pod weight, and partitioning coefficient. In both years, disease ratings differed among genotypes beginning 58 d after planting and were more effective for distinguishing among genotypes throughout the growing season than percentage leaf necrotic area. Fourteen of the 16 genotypes had similar V stages throughout the growing season. Vegetative weights of disease-susceptible cultivars did not exceed 165 g plant⁻¹, while many resistant lines exceeded 250 g plant"1. Susceptible-cultivar partitioning coefficients generally exceeded 80%, while resistant lines ranged from 20 to over 80%. Pod initiation in resistant lines lagged behind that of susceptible cultivars by 10 to 30 d, even if resistant lines had high partitioning coefficients. Use of disease rating combined with selection of high partitioning lines with early initiation of pod production may contribute to development of desirable cultivars. Journal Series no. 9752.
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