GENETIC-ANALYSIS AND INTERRELATIONSHIPS BETWEEN TRAITS FOR COOKING TIME, WATER-ABSORPTION, AND PROTEIN AND TANNIN CONTENT OF ANDEAN DRY BEANS

A knowledge of the relative proportion of additive and nonadditive gen etic variances for complex traits in a population forms a basis fdr st udying trait inheritance and can be used as a tool in plant breeding. A North Carolina Design II mating scheme was used to determine the inh eritance of cooking time, protein and tannin content, and water absorp tion among 16 genotypes of dry bean (Phaseolus vulgaris L.) representa tive of the Andean Center of Domestication. Heritability and the degre e of dominance for the traits were also calculated to provide guidelin es for adopting breeding strategies for cultivar development. Thirty-t wo progeny resulted from the matings and these were assigned to two se ts of 16 progeny each. Variances due to general combining ability (GCA ) and specific combining ability (SCA) were significant for the traits . The GCA was larger in all cases. Narrow-sense heritability for prote in, tannin, water absorption, and cooking time averaged 0.88, 0.91, 0. 77, and 9.90, respectively. Degree of dominance estimates indicted tha t the traits were governed by genes with partial dominance except, hi one case, tannin had a degree of dominance value of zero, indicating n o dominance. The phenotypic correlation (-0.82) between water absorpti on and cooking time justifies using the water absorption trait as an i ndirect selection method for cooking time. With regard to parent selec tion in crosses, significant differences between GCA females and GCA m ales suggested cytoplasmic influences on trait expression. Hence, the way a parent is used in a cross (i.e., as female or male) will offset trait segregation. Using fast-cooking bean cultivars in conjunction wi th fuel-efficient cooking methods may be the best strategy to conserve fuelwood and help reduce the rate of deforestation in East and Centra l Africa.