Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/1996
Publication Date: N/A
Interpretive Summary: Despite the wide acceptance of dry bean as a food and it's nutritional superiority compared to other crops, beans do not supply their inherent nutrients to humans to the fullest potential. Two factors leading to bean underutilization in diets are the long time required to cook beans palatable for consumption and the proteins and starch can be digested, and a low protein assimilation. Genetic variability for cooking time and other nutritional factors exists in dry bean which provides an opportunity to improve beans for traits of interest through plant breeding. Planned genetic advances for traits under selection require the breeder to have a knowledge of the inheritance of the traits. An experiment was conducted to determine the inheritance of cooking time, water absorption, protein, and tannin (a chemical in seed coats of colored beans that makes protein difficult to digest). Sixteen genotypes that varied for the traits were mated in a special way to study the transmission of genes from parent to offspring. Resemblances among offspring indicated that genes influencing all the traits added to trait expression in a linear fashion. This fact makes it easy to make breeding advances and predict trait performance in successive cycles of selection. A large association between water absorption and cooking time was noted and indicated that cooking time can be selected indirectly by choosing genotypes that take up water rapidly during soaking. The determination of cooking time is expensive and time consuming, but the determination of water absorption is rapid and inexpensive. Selection based on water absorption as opposed to measuring the cooking time per se and the selection and use of fast cooking varieties increases breeding efficiency and saves resources.
Technical Abstract: The long time required to cook beans palatable for consumption and the inefficient burning of fuel through the employment of open wood fires in Eastern and Central Africa exacerbates deforestation in the region. Energy savings estimates from Eastern Africa suggest that the adoption of bean cultivars that cook more quickly than those currently produced and consumed may save significant fuelwood and help reduce deforestation. No information is available regarding the inheritance of cooking time, and the ease of selection. This study was conducted to determine the inheritance of cooking time, protein and tannin content and water absorption and determine if water absorption could be used as an indicator of cooking time. To ascertain the inheritance of traits, genetic variances were estimated from a North Carolina Design II mating scheme. Trait determination was due to both additive and dominance variance; however, the additive portion was larger in all cases. Narrow sense heritability for protein, tannin, water absorption, and cooking time averaged 0.88, 0.91, 0.77 and 0.90, respectively. Degree of dominance estimates indicted that the traits were governed by genes with partial dominance. The phenotypic correlation (-0.82) between water absorption and cooking time justifies using the water absorption as an indirect selection method for cooking time. Based on gain from selection estimates breeding progress to reduce cooking time would be steady but slow. The use of fast cooking bean cultivars in conjunction with fuel efficient cooking methods may be the best strategy to conserve fuelwood in Eastern and Central Africa.