Grain yield of soybean cultivars using different densities and sowing dates in a high-altitude region of south Brazil

The study aimed to evaluate the performance of soybean cultivars at different sowing dates and plant densities. Two experiments were carried out at FAPA (Fundação Agrária de Pesquisa Agropecuária [Agrarian Foundation for Agricultural and Cattle Research]), located at 25?33’ S latitude, 51?29’ W longitude and with 1.100 meters of altitude in Guarapuava, PR [Paraná], Brazil, in two agricultural harvests (2010/2011 and 2011/2012). The experimental design was in randomized blocks and split plots, in which the sowing dates (10/20, 11/18 and 12/10) were allocated by plot, the densities (250, 350 and 450 thousand plants ha-1) by subplot and the cultivars (BMX Energia, BMX Apolo, BMX Ativa, FPS Júpiter, V_Top, NS 6631, TMG 7161 and BRS Tordilha) by sub-subplot. The agronomic characteristics, grain yield and yield components were evaluated. Sowing dates and plant densities affected the agronomic characteristics, grain yield and yield components of soybean. The best sowing dates for lodging-tolerant cultivars are 10/20 and 11/18, and the best densities are 350 and 450 thousand plants ha-1, while lodging-susceptible cultivars respond best for sowing dates of 11/18 and 12/10 and densities from 250 to 350 thousand plants ha-1