Critical components and loss factors in inoculated and non-inoculated cowpea varieties grown in the Brazilian Amazon

The cowpea (Vigna unguiculata [L.] Walp) is of social and economic importance in developing countries. There are several factors that lead to low cowpea yields in tropical regions, such as pests and low technological development. This study aimed to identify and quantify losses in the critical component of production, and the key loss factors for three cowpea varieties (buttermilk, milk, and vinegar) grown in Santarém, Brazil, and inoculated or not with Bradyrhizobium japonicum. Crop life tables, loss factors, and production components of the three varieties were evaluated. Differences in yield and total losses were observed between varieties, but not between treatments with and without inoculant. In all three varieties, flowers were a critical component of production, and flower abortion was the key factor behind losses. Grain losses contributed significantly to total losses. The factors that contributed the most to grain component losses in all three varieties were malformation of grains and non-fertilisation of eggs. Inoculation increased losses through increased abortion of flowers in the buttermilk and milk varieties. Inoculation also increased damage caused to cowpea plants by cowpea weevils, Callosobruchus maculatus, in the buttermilk variety. Inoculation increased the total losses in the three varieties studied.