Genetic divergence in bean land races and research-developed cultivars

It has been recognized that the germplasm of bean (Phaseolus vulgaris L.) under use by Brazilian small-holders presents a great genetic variability. The characterization of such variability, may contribute to increase efficiency in conservation and the use of that germplasm. The aim of this work was to characterize the variability present in bean land races, to compare it with that of research-developed cultivars and locate all the genotypes in similarity groups. Thirty-seven land races and 14 research-developed cultivars were evaluated by the application of 40 bean morphologic descriptors; most of them contained in the set of descriptors needed for legal protection. Principal component analysis and Ward's hierarchical method were multivariate techniques employed in the study. Inefficient or redundant descriptors were identified and four different similarity groups of cultivars were defined. Land races displayed much larger variability as compared to research-developed cultivars, suggesting the importance of their potential for bean breeding programs.