Evaluation of selected cowpea varieties under competition with weeds

Resumo

Cowpea is cultivated in the semi-arid region of Brazil and in various other countries, generally employing
traditional varieties, which are grown as intercrops by low-income, illiterate farmers who lack technical assistance. Under such
conditions, the use of herbicides is limited, and weed control is usually carried out by hoeing. Combining more varieties that
are more competitive against weeds, and planting at higher planting densities using different cropping practices could reduce
the work of weeding. In a preliminary study, 48 traditional varieties of the cowpea were grown with only one weeding, and
evaluated for dry-grain yield. The aim of the present study was to evaluate the green- and dry-grain yields of six varieties: three that
proved to be more productive (Umarizal, Itaú and Upanema), and three that had low yields (Mossoró, Santa Cruz and São Miguel) in the
preliminary evaluation. The varieties were submitted to two types of weed-control management (one or two weedings). A randomised
block design was used, in split plots with five replications. Weed management was applied to the plots, and the traditional
varieties to the subplots. It was found that, in terms of the effect on the yields under evaluation, there was no difference in the
number of weedings. The Umarizal, Itaú, Upanema and Mossoró varieties were the best for green-grain production, with the
first two also being superior in the production of dry grain.