Crop Science · 1972 · 15 citations · 0 references
AgricultureGeneticsPlant SciencesHybrid BreedingPlant GeneticsPlant PhysiologyCombining Ability EvaluationGenotype-by-environment InteractionHybrid Performance EvaluationHybrid Performance TestingPhenotyping For Disease ResistancePlant Breeding GeneticsAdditive Genetic ModelsAdditive Genetic VarianceAdditive VarianceCombining Ability EffectsCombining Ability TestingGeneral Combining Ability VarianceGenetic Variance AnalysisGenotype-environment Covariance
Seven cultivars of Nicotiana tabacum L. (four Maryland and three cigar types) and 21 F 1 hybrids were grown at three locations for 2 years. During August, data were collected on leaf damage caused by air pollutants, primarily ozone. This condition was referred to as weather fleck. Ozone causes small necrotic lesions usually 0.2 to 0.5 cm in diameter. Plants were scored on a scale of 1 to 5 (1 = no damage, 5 = severe damage). Comparison of parent (2.34) and F 1 hybrid (2.37) performance indicated no significant amounts of heterotic resistance to weather fleck. Diallel analyses of variance of the F 1 hybrid generation suggested an appreciable amount of variance due to general combining ability (GCA) and the absence of variance due to specific combining ability (SCA). Genetic effects were stable with respect to locations and years. The genotype × environment interactions for the six environments were small. The predominance of additive genetic variance in this material suggests that progress could be made through selection.