Cowpea Constraints and Breeding in Europe

Abstract

Cowpea (Vigna unguiculata (L.) Walp.) is a legume with a constant rate of cultivation in Southern European countries. Consumer demand for cowpea worldwide is rising due to its nutritional content, while Europe is constantly attempting to reduce the deficit in the production of pulses and invest in new, healthy food market products. Although the climatic conditions that prevail in Europe are not so harsh in terms of heat and drought as in the tropical climates where cowpea is mainly cultivated, cowpea confronts with a plethora of abiotic and biotic stresses and yield-limiting factors in Southern European countries. In this paper, we summarize the main constraints for cowpea cultivation in Europe and the breeding methods that have been or can be used. A special mention is made of the availability plant genetic resources (PGRs) and their potential for breeding purposes, aiming to promote more sustainable cropping systems as climatic shifts become more frequent and fiercer, and environmental degradation expands worldwide.

Crop Landraces and Indigenous Varieties: A Valuable Source of Genes for Plant Breeding

“…So far, several cowpea landraces that possess genes involved in abiotic stress tolerance and biotic stress resistance have been utilized in conventional breeding schemes [ 51 , 79 ]. In molecular breeding, GWAS has proven to be a valuable technique in associating genomic regions with interesting traits such as drought and heat tolerance, mainly using breeding lines, MAGIC populations of cowpea, and to a very small extent landraces material [ 80 , 81 , 82 ].…”

“…Cowpea (Vigna unguiculata (L.) Walp.) is a diploid (2n = 2x = 22) warm season legume with landraces being the most common cultivated genetic material (conserved on-farm) [51]. A greater number of cowpea landraces (22,161) than the number of advanced/improved cultivars (516) and breeders' lines (771) is also conserved ex situ in genebanks worldwide [52].…”

“…Advances in QTL mapping of cowpea traits resulted in the identification of numerous QTLs [51,54] that led to significant progress in genome sequencing. For QTL analysis, recombinant inbred lines (RILs) have been used; some of which were derived from crosses between domesticated and wild cowpea [55][56][57], between cowpea and yard-long bean [58][59][60], or between wild cowpea and yard-long bean [23,61].…”

Evaluation of Cowpea Landraces under a Mediterranean Climate

“…Cowpea cultivation in Southern Europe, including Mediterranean countries, starts in late spring (late April) and lasts until the beginning of autumn (early October) [ 1 , 50 , 51 ]. During the summer period, cowpea is confronted with water scarcity and high air temperatures, like in many other areas of the world [ 52 , 53 ], while in many cases, cultivation faces additional limiting soil factors [ 54 ]. In the countries around the Mediterranean basin, a remarkable number of cowpea landraces are still cultivated on a small scale by farmers mainly for their own use and consumption of either their young, tender pods or their seeds, which are rich in protein, carbohydrates, and nutrients [ 55 , 56 ].…”

Weed-Hoeing Periods in Cowpea Cultivation under Direct and Conventional Systems

“…Cowpea ( Vigna unguiculata (L.) Walp. ), a crop widely consumed in African countries, has garnered the interest of breeders on a global scale in recent times [ 1 ]. In Brazil, commonly known as “cowpea macassar”, “cowpea-de-corda”, or “cowpea-caupi”, it is a legume species with a high protein content and expressive socioeconomic importance as one of the most consumed grains in Brazil, where it is widely grown in the north and northeast regions of the country due to its adaptation to local edaphoclimatic conditions [ 2 ].…”