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Scope and methods of study. Two experiments were conducted. In experiment 1, five adapted soybean (Glycine max (L.) Merr.) cultivars (Oksoy, Essex, Forrest, Douglas, and Sohoma), one corn earworm (Heliothis zea (Boddie)) resistant line (N80-50232), their 15 F, and 15 F2 generations were evaluated. In experiment 2, three adapted cultivars (Oksoy, Douglas, and Sohoma), the corn earworm resistant line (N80-50232), their six F, six F2, and twelve backcross (six BC, (P x F) and six BC2 (P2 x F) generations were evaluated. The objectives were: to determine the relative resistance to corn earworm among the soybean genotypes, to estimate general (GCA) and specific (SCA) combining ability effects for corn earworm resistance as determined by larval and pupal survival, larval and pupal weight, and length of larval and pupal stage, to estimate broad-sense heritability for these characters, and to estimate the correlations between these characters. Seeds of these plant genotypes were space planted at two locations, near Stillwater and Perkins, Oklahoma, in a RCB design with 9 replications in 1987. Antibiosis was studied in a growth chamber using leaves of these genotypes and laboratory-reared corn earworm larvae. Statistical analyses were conducted on the populations common to both experiments. Findings and conclusions. Corn earworm resistance of N80-50232 and its hybrids resulted in smaller larvae and pupae, and a longer larval stage. F hybrids involving N80-50232 were intermediate for larval and pupal weight, indicating additive gene effects. N80-50232 had desirable GCA effects for larval and pupal weight and length of larval stage. SCA effects of Oksoy/N80-50232 and Douglas/Sohoma for length of larval stage were significant and desirable. Significant genetic variability was present for larval and pupal weight and length of larval stage, in some populations. The highest estimates involved N80-50232 as one of parents. Larval weight and pupal weight were positively correlated, and each was negatively correlated with length of larval stage.
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