The use of plant bioprotectors constitutes a modern tactic of seed treatment for corn (Zea mays) disease control without environmental hazards. Experiments were carried out under laboratory and field conditions in Passo Fundo, RS, and in Pato Branco, PR, Brazil, aimed at evaluating the effects of seed microbiolization on seed pathogens, seed emergence, and corn yield. In the laboratory, most bioprotectants significantly reduced pathogen recovery from infected corn seeds. In field experiments, in 1997, in Passo Fundo, only Trichoderma harzianum (T-22) significantly increased seedling emergence and corn yield. All bioprotectors significantly improved seed emergence in Pato Branco. Paenibacillus macerans (144), T. harzianum (T-22), Flavimonas oryzihabitans, and Pseudomonas putida biotype B also provided a significant yield increase over untreated control. T. harzianum treatment showed a yield increase of 615 kg/ha over the untreated check. In 1998, in Passo Fundo, P. macerans (144), F. oryzihabitans, and Agrobacterium radiobacter provided the highest increases in seedling germination. All biological treatments, except F. oryzihabitans and Bacillus subtilis, showed significant yield increases. In Pato Branco, Pseudomonas putida biotype B, F. oryzihabitans, and P. putida biotype A (M 970841) provided the best corn seed emergence Paenibacillus. macerans (144), T. harzianum (T-22), F. oryzihabitans, A. Radiobacter, and B. subtilis significantly increased grain yield.Seed microbiolization is a promising technological alternative for corn seed treatment in Brazil.
