The quality of leguminous vegetables as influenced by preharvest factors

The cultivation of most legumes, aims to the production of either dry seeds consumed by humans, also known as pulses, or animal fodder. However, some legumes are cultivated for fresh consumption either as pods or as immature seeds. The economically most important legumes consumed as vegetables are green pods of common bean, cowpea, faba bean, snow pea (mangetout) and green pea seeds. As a rule, the legume vegetables are consumed after cooking and in many countries, they may be used to cover primary nutritional needs, because their protein content is high in comparison with most other vegetables. Furthermore, the legume vegetables, which have distinct organoleptic properties when compared to pulses, are also considered important sources of carbohydrates, essential minerals, vitamins, several other antioxidants and health promoting compounds, and dietary fiber. On the other hand, legume vegetables constitute a low-fat foodstuff. Legume vegetables may contain some antinutritional factors, particularly lectins, phytic acid, saponins, oligosaccharides belonging to the raffinose-family, and vicin and convicin in faba bean, but the levels of most of them are lower than in dry pulses and generally do not constitute a constraint to their consumption. Breeding is one of the most efficient tools to reduce the concentrations of antinutritional factors and increase the levels of health promotic compounds and the taste in legume vegetables. Among the legume species frequently consumed as vegetables, a relatively large number of local accessions and landraces are available, which constitute a valuable genetic material for breeding programs aiming at improving their quality. Breeding of more resilient cultivars to combined stress conditions characterized by a higher nutritional value entails also a better understanding of the physiological mechanisms underlying the biosynthesis of health promoting and antinutritional compounds, as well as the plant adaptation to adverse environmental conditions. Last but not least, agronomical practices, such as crop establishment and plant density, fertilization, irrigation, weed control, and harvesting time and practices play a crucial role for the quality of legume vegetables and deserve special attention.