Avaliação de índices de emergência de soja e de milho em plantio direto no sul do Brasil.

Abstract

The rate of plant emergence was the parameter chosen to evaluate the efficiency of the seeding operation. Six seeders for soybean and eight for corn were field tested from 1994 to 1995, at the Embrapa Trigo, Passo Fundo, RS. An experimental design of blocks at random was used, in which the main plot was the seeders, and the subplots the speed of seeding, with three replicates. Highly significant dif-ferences in the rate of plant emergence were observed for soybean. Plant emergence was 14 % lower when the seeder was equipped with disc coulters, probably due to shallower seeding depth (4.5 cm for discs versus 6.0 cm for narrow tines), since a dry spell occurred during plant emergence. No difference in rate of plant emergence was observed for corn. A correlation among seeder with disc coulters and speed of seeding was observed. At the highest speed the seeders equipped with disc coulters reduced plant emergence in 9.0 %, while the seeders equipped with narrow tines reduced plant emergence in 2.1 % only.