POPULATION DENSITY ON COWPEA CULTIVARS WITH DIFFERENT GROWTH HABITS IN THE MATOPIBA REGION

The aim of this study was to assess the productive performance of cowpea cultivars with different growth habits as a function of population density in the MATOPIBA region, Brazil. The experiments were carried out in Magalhaes de Almeida, MA in the agricultural season 2014/2015. The cultivars BRS Itaim, BRS Tumucumaque, and BRS Pajeu, which present an erect, semi-erect, and semi-prostrate growth habits, respectively, were assessed. For the erect and semi-erect cultivars, a total of 8, 12, 16, 20, 24, and 28 plants m(-2) were used whereas for the semi-prostrate cultivar, a total of 2, 6, 10, 14, 18, and 22 plants m(-2) were used. The experimental design was a randomized block design with four replications and treatments composed of plant densities. Grain yield and number of pods per area presented a quadratic response to the increased plant density whereas a decreasing linear response was observed for the number of pods per plant. The maximum grain yield of erect, semi-erect, and semi-prostrate cultivars were 1,076 kg ha(-1) (19.5 plants m(-2)), 1,252 kg ha(-1) (18.7 plants m(-2)), and 755 kg ha(-1) (14.5 plants m(-2)), respectively. The number of pods per area was the character that most correlated (P<0.01) with grain yield, regardless of the plant growth habit.