Lablab purpureus-A Crop Lost for Africa?

Abstract

In recent years, so-called 'lost crops' have been appraised in a number of reviews, among them Lablab purpureus in the context of African vegetable species. This crop cannot truly be considered 'lost' because worldwide more than 150 common names are applied to it. Based on a comprehensive literature review, this paper aims to put forward four theses, (i) Lablab is one of the most diverse domesticated legume species and has multiple uses. Although its largest agro-morphological diversity occurs in South Asia, its origin appears to be Africa. (ii) Crop improvement in South Asia is based on limited genetic diversity. (iii) The restricted research and development performed in Africa focuses either on improving forage or soil properties mostly through one popular cultivar, Rongai, while the available diversity of lablab in Africa might be under threat of genetic erosion. (iv) Lablab is better adapted to drought than common beans (Phaseolus vulgaris) or cowpea (Vigna unguiculata), both of which have been preferred to lablab in African agricultural production systems. Lablab might offer comparable opportunities for African agriculture in the view of global change. Its wide potential for adaptation throughout eastern and southern Africa is shown with a GIS (geographic information systems) approach.

Fig. 1

Principal component analysis from 151 AFLP markers of 53 Lablab purpureus accessions indicating narrow genetic diversity of southern Indian landraces (UAS cluster) maintained at UAS Bangalore as opposed to members from a core collection proposed by Pengelly and Maass (2001) (Modified from Venkatesha et al. 2007)

Fig. 2

Dendrogram of the diversity among 33 Lablab purpureus accessions assessed by AFLPs (Amplified Fragment Length Polymorphism), applying UPGMA (Unweighted Pair Group Arithmetic Means Algorithm), and hierarchical cluster analysis. Core collection accessions proposed by Pengelly and Maass (2001) in dotted lines, two ILRI-accessions of subsp. uncinatus in dashed lines; eastern African landraces in bold lines; TZA = Tanzania. (Modified from Tefera 2006)

Fig. 3

In four villages of Arumeru district, Tanzania, 30 farmers of different approximate age groups were interviewed about land use changes along a transect from (a) sub-humid to (b) semi-arid; this was compared to records and a current assessment. (Derived from Ngailo et al. 2003)

Fig. 4

Maps of ecogeographic surveys of Lablab purpureus, predicting (a) high probability of occurrence of the species, based on 643 herbarium specimens and germplasm accessions by applying FloraMap® (Modified from Ramme 2002); or (b) high and marginal suitability of the crop from the Tropical Forages database (Cook et al. 2005). The line includes the high probability area generated by FloraMap