Effect of Plant Densities On Growth and Yield of Cowpea Cultivars in Fall-Winter Season of Southeastern Brazil.

Cowpea [Vigna unguiculata (L.) Walp.] is a drought tolerant plant and adapted to low soil fertility, has a short cycle, and lower production cost, so it is becoming an interesting option as a second crop during fall-winter in the Midwest and Southeast of Brazil. However, there is no information about this crop in Southeastern Brazil. The objective of this study was to evaluate the growth and yield of two semi-upright cowpea cultivars (BRS Guariba and BRS Novaera) on five plant densities (100,000; 200,000; 300,000; 400,000; and 500,000 plant ha^-1) during fall-winter (out-of-season). The experiment was conducted in Botucatu, São Paulo State, Southeastern Brazil. The design was a randomized blocks in factorial scheme 2x5, with four replications. The seeds were sown in mid-March with row spacing of 0.45 cm. Were evaluated: leaf area, leaf area index, final plant population, main branch length, number of lateral branches, height of first pod insertion, number of pods per plant, number of grains per pod, 100-grain weight and grain yield. The cultivar BRS Guariba had less lateral branches per plant. Leaf area of each plant, the number of lateral branches, number of pods per plant, number of grains per pod and 100-grain weight of both cultivars were reduced by increasing plant density. Increasing plant density increased the leaf area index. The maximum yield was obtained with the estimated density of 300,000 plant ha^-1.