描述
The cowpea (Vigna unguiculata) is one of several species of the widely cultivated genus Vigna. Four subspecies are recognised, of which three are cultivated: Vigna unguiculata subsp. dekindtiana, the wild relative of the cultivated subspecies Vigna unguiculata subsp. cylindrica, cultivated, catjang Vigna unguiculata subsp. sesquipedalis, cultivated, yardlong beans Vigna unguiculata subsp. unguiculata, cultivated, black-eyed pea Cowpeas are one of the most important food legume crops in the semiarid tropics covering Asia, Africa, southern Europe and Central and South America. A drought-tolerant and warm-weather crop, cowpeas are well-adapted to the drier regions of the tropics, where other food legumes do not perform well. It also has the useful ability to fix atmospheric nitrogen through its root nodules, and it grows well in poor soils with more than 85% sand and with less than 0.2% organic matter and low levels of phosphorus. In addition, it is shade tolerant, so is compatible as an intercrop with maize, millet, sorghum, sugarcane, and cotton. This makes cowpeas an important component of traditional intercropping systems, especially in the complex and elegant subsistence farming systems of the dry savannas in sub-Saharan Africa. In these systems the haulm (dried stalks) of cowpea is a valuable by-product, used as animal feed. Research in Ghana found that selecting early generations of cowpea crops to increase yield is not an effective strategy. Francis Padi from the Savannah Agricultural Research Institute in Tamale, Ghana, writing in Crop Science, suggests other methods such as bulk breeding are more efficient in developing high-yield varieties. Cowpeas are a common food item in the Southern United States, where they are often called black-eyed peas or field peas. Two subcategories of field peas are crowder peas, so called because they are crowded together in their pods, causing them to have squarish ends, and cream peas. In India, in Oriya, it is called jhudunga, in Bengali, it is called barboti kolai, in Kannada, it is called Alasande, in Telugu, it is called Alasandalu, Bobbarlu. In Hindi, it is called lobhia or bura (when used as a string bean). In Gujarati, these are called chola or chowla. In Marathi, these are called chawali or chavali. According to the USDA food database, the leaves of the cowpea plant have the highest percentage of calories from protein among vegetarian foods.