Lablab purpureus—A Crop Lost for Africa?

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

Lablab effect on soil properties and subsequent maize-cowpea intercrop

The ability of herbaceous legumes to supply nitrogen to subsequent cereal crops could be harnessed to alleviate the difficulties in cereal production due to poor soil fertility and expensive inorganic fertilizers. Field  experiments were carried out in Zaria, Nigeria to determine the soil  improvement potential of Lablab purpureus accessions and evaluate the grain and fodder response of maize-cowpea intercrop to one-year fallow rotation. Six lablab accessions (ILRI 147, ILRI 4612, PI 388013, PI  183451, PI 195851 and PI 532170) of different maturity groups and natural vegetation represented the fallow treatments. The maize and cowpea test crops were TZE Comp.5 W and IT99K-241-2, respectively. Lablab fallow improved soil organic carbon, nitrogen, phosphorus and  potassium. The early maturing PI 388013 increased phosphorus and  potassium by 179 and 100 %, respectively whereas extremely late  maturing PI 195851 increased nitrogen by 18 % while another early maturing accession PI 183451 increased organic carbon by 11 % relative to natural fallow. Lablab grain and fodder yields ranged from 0.6 to 1.4 t ha-1 and 2.4 to 3.9 t ha-1, respectively. Compared to natural fallow, intercropping maize on plots previously planted to ILRI 4612 led to significantly higher fodder yield (2.8 to 4.1 t ha-1) meaning an increase of 46 %. Lablab or natural fallow did not influence grain yield and 500-seed-weight of maize; it did not also influence 100-seed-weight, grain and fodder yields of cowpea. The fallow period for lablab may not have been long enough for significant improvement of soil properties to impact maize and cowpea performance in relation to natural fallow. The study showed that a maize-cowpea intercrop following lablab in rotation can be of rational inclusion in the farming system of the zone.Keywords: lablab, intercropping, maize, cowpea, soil properties

Genomics-assisted breeding for drought tolerance in cowpea

Published online: 02 July 2019The importance of cowpea, Vigna unguiculata, in human and animal nutrition and sustainability of soil fertility are recognized globally especially in sub-Saharan Africa (SSA) where the crop is mainly produced in the Savanna and the Sahelian agro ecologies. However, cowpea productivity is adversely affected by both biotic (insect pests, diseases, parasitic weeds, nematodes) and abiotic (drought, heat, low soil fertility) constraints. Appreciable progress has been made in the improvement of cowpea for resistance to some biotic stresses particularly diseases such as bacterial blight, ashy stem blight, marcophomina, parasitic weeds like Striga and Alectra and some insects like aphid, leaf and flower thrips among others. There is need for intensifying research activities with focus on improving cowpea resistance to abiotic stresses. As a crop grown commonly in arid regions, cowpea is subjected to seedling stage, midseason and terminal droughts. In the recent past, the amount of rainfall, during the cropping season in the dry savannah regions of SSA, is getting less. Consequently the cropping season is getting shorter occasioned by late commencement or early cessation of the rain. Farmers in the cowpea producing areas of SSA generally have no access to irrigation hence their crops are grown under rain-fed conditions. With the impending higher frequency of drought in the dry savannah region due to climate change, efforts should be made in developing climate resilient cowpea varieties that farmers will grow. Efforts have been made in enhancing tolerance to drought in some improved cowpea varieties using conventional breeding but progress has been slow in this regard. Drought tolerance is a complex trait and many genes are involved in its inheritance. Pyramiding of these genes in improved varieties would therefore, be desirable. Such varieties with pyramided genes are likely to be stable in performance over the years and across several locations in the savannahs. Recent developments in molecular biology could play significant role in the development of such resilient varieties. In a number of crops, molecular markers associated with resistance loci have been identified and are being used in marker assisted breeding. Marker assisted backcrossing (MABC) is the choice when single traits that are simply inherited are to be moved to varieties with superior performance but lacking in the trait being transferred. Also, marker assisted recurrent selection (MARS) has shown promise in accumulating multiple genes in improved varieties of some crops. Some work has been initiated in cowpea on the use of MARS to pyramid resistance to Striga, yield and drought. Results obtained so far show the potential of this method in pyramiding desirable genes in cowpea. As more resources get committed to cowpea research a solid foundation would be established for the generation of molecular tools that should facilitate their routine application to the improvement of the crop