The objective of this study was to investigate the possibility of index selection for pod yield and leafspot resistance, causal organisms Cercospora arachidicola Hori and Cercosporidium personatum (Berk. and Curt.) Deighton, in peanut (Arachis hypogaea L.). Eleven crosses were evaluated in the S1 and S2 generations under natural disease pressure for pod yield and disease reaction. Leafspot severity was measured by leaf necrotic area and defoliation. Variances for each trait and covariances between traits were estimated by progeny analysis. Economic weights assigned to the different characters were derived as the ratio of the pod yield for a genotype to the theoretical pod yield gain from leafspot resistance. Indices were constructed and their efficiency both as predictor of the breeding value and relative to individual selection for either trait was evaluated. Index selection for increased pod yield and reduced leafspot susceptibility was between 87% and 100% as efficient as direct selection for either trait. Combining several leafspot severity readings with pod yield did not improve the efficiency of the index. Fourteen to 17% of the breeding value of the population was accounted for by the traits combined in various indices. This indicated that there is potential for improvement of these indices.

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1Contribution from the University of Florida, Institute of Food and Agricultural Sciences. Journal Series No. 7679.