The management of sowing density on yield and lodging in the main oat biotype grown in Brazil

The sowing density management in the main oat biotype cultivated in Brazil can bring yield gains with reduced lodging. The aim of this study was to sow the density adjustment of early cycle oat cultivars and reduced stature to increase biomass and grain yield with reduced lodging, considering high and low N-residual release succession systems in different years. The study was carried out in 2011, 2012 and 2013 in randomized blocks experimental design with four replications in factorial scheme 4 × 2, for sowing density (100, 300, 600 and 900 seeds m-2) and oat cultivars (Brisasul and URS Taura) in the corn/oat and soybean/oat succession systems. In each succession system two experiments were conducted, one to quantify the biomass production rate, and the other, aimed at estimating the grain yield and lodging. Regardless of year and cultivar, the main oat biotype grown in Southern Brazil evidences optimal sowing density around 500 seeds m-2 in the biomass and grain expression yield in the corn/oat and soybean/oat succession systems. In the soybean/oat succession system, the use of optimal density can favor the plant lodging, especially in favorable cultivation years. The corn/oat succession system through lower release of N-residual proves to be efficient concerning the grain yield expression and reduced lodging in the use of adjusted density.     Key words: Avena sativa L., succession systems, climate change, biomass, regression.