Plant density of hybrid maize at early sowing date in Southern Brazil

The choice of plant density and sowing date tire important management practices to determine maize g rain Yield. The objective of this study was to evaluate the effect of plant density on grain yield and its components for two maize hybrids at early sowing date (August) in the State of Rio Grande do Sul. South ern Brazil. The experiment was carried out it? Eldorado do Sul (RS). during the 2006107 growing season. Treatments consisted of four plant densities (5.5, 7.3. 9.1 and 11pl m(-2)) and two hybrids with contrasting leaf architecture. Dow 2B587 (decumbent leaves) and NB 4214 (erect leaves). The sowing date was August 22, 2006. Grain yield for the decumbent leaf hybrid increased linearly with the increment in plant density from 5.5 tip to 11pl m(-2), reaching 16t ha(-1). Grain Yield of the erect leaf hybrid, in turn. was maximized at 9.4pl m(-2). The number of ears per square meter was the Yield component that better explained maize productivity increase with increasing plant density. The use of plant populations higher than 9pl m(-2) was an effective strategy to improve maize grain yield grown under high management level, at early sowing date (August) in Southern Brazil.