Landraces ofPhaseolus vulgaris (Fabaceae) in Northern Malawi. I. Regional variation

Abstract

Bean germplasm collections in northern Malawi revealed the existence of diverse landraces, which have probably been maintained by the local farmers as heterogeneous mixtures since the precolonial introduction of Phaseolus vulgaris into eastern Africa. The various seed types comprising these mixtures are known by an array of local names, reflecting farmer perceptions of seed color and pattern, eating quality, plant structure, origin, and other characteristics. A principal components analysis of morphological, phenological, and agronomic metrical traits for 375 lines randomly selected from 15 landraces revealed a clinal pattern, with the northern and southern areas forming the extremes. Genetic distances, based on the first six PCs, indicated greater between-area variability than within-area variability. Bean landrace diversity in Malawi is likely the result of a complex interplay among forces that generate variability such as outcrossing and human and environmental selection.