Morphological variation of sorghum landraces from semi-arid areas of Zimbabwe

Abstract

Sorghum (Sorghum bicolor) is one of the most important cereal crops cultivated in, the semi-arid areas of Zimbabwe where persistent drought, high temperatures and poor edaphic conditions are endemic. Because of their adaptation, landraces are the mainstay of smallholder agriculture in such areas. Unfortunately, limited studies have been done to quantify the genetic diversity of this material in order to formulate the necessary conservation strategies. This study analysed the genetic diversity of 47 sorghum landraces from two districts of Zimbabwe, Nyanga North and Tsholotsho using 24 Sorghum agromorphological descriptors. Genetic similarities (Manhattan coefficient) were calculated and genetic relationships between accessions were analysed by principal component analysis and cluster analysis. The landraces grouped into six clusters according to the geographical location where they were collected from, suggesting environmental adaptation. Accessions with the same name had a tendency to group together, although some material was found scattered throughout the dendrogram. Agromorphological traits were highly variable even for landraces with the same farmer-given name and source. The results also alluded to the heterogeneity of farmer varieties, whose naming appears to be a function of a few traits. The study suggests that optimisation of on-farm conservation strategy for this germplasm should primarily focus on high diversity areas and perhaps recognise those traits envisaged to be of importance by farmers for varietal identification