Microrganismos eficientes no tratamento de sementes de milho

Abstract

Corn is a cereal that has great versatility of use, having great importance for Brazilian agriculture. In the production context, seed treatment with fungicides and insecticides is a tool used to control pests and ensure initial plant stand, as well as other products, which can be added to improve seed germination and vigor, such as micronutrients. Considering the organic corn production, there is a lack of alternatives for seed treatment, since the use of pesticides and traditional inputs is not allowed. Thus, the objective of this work was to evaluate the efficiency of efficient microorganisms in the physiological and sanitary potential of corn seeds. The experiment was carried out in a completely randomized design in a two-factor scheme: four corn cultivars (three open-pollinated varieties: Argentino branco, Cunha, and Palha roxa, all without seed treatment; and a commercial hybrid: FS533PWU, with industrial seed treatment that contained fungicide and insecticide; and three doses of efficient microorganisms (0, 25 and 50%). The variables measured were seed moisture content, percentage of germination, percentage of normal seedlings at the first germination count, germination rate index, and incidence of fungi in the seeds (Penicillium spp., Aspergillus spp., and Fusarium spp.). In all analyzes, the seeds were previously inoculated with the efficient microorganisms for 5 minutes. The data obtained were submitted to analysis of variance, with splitting with Tukey's test of means and regression analysis, according to the ANOVA result. The cultivars showed different moisture contents, but none exceeded the limit of 13% recommended for storage. For germination, only the cultivar effect was significant, with the hybrid and Cunha showing the highest percentage of normal seedlings (94 and 90%, respectively). A significant interaction between cultivar and dose was obtained for the first germination count. A positive linear effect was verified for the hybrid, showing a synergism between industrial seed treatment and efficient microorganisms. On the other hand, for the open pollinated varieties, there was an inverse effect (negative linear effect), i.e., the higher the dose of efficient microorganisms used, the lower the seed vigor. Thus, the use of efficient microorganisms is not recommended when vigor is measured by the first germination count in open-pollinated varieties. In the germination rate index (GRI), in turn, there was a significant effect of cultivar and dose. The highest GRI was obtained for the hybrid (20), followed by the 50% dose of efficient microorganisms (19). Thus, when seed vigor was evaluated by the GRI, the use of efficient microorganisms was beneficial. The efficient microorganisms also had a positive effect on the sanitary quality of the seeds, causing the decrease of Penicillium spp. and Aspergillus spp., where the dose of 50% of efficient microorganisms was recommended for seed treatment. For Fusarium spp. there was a difference only between cultivars, with Argentino branco and Palha roxa showing the lowest percentages of infection, both with 17%. Therefore, corn cultivars show different responses to seed inoculation with different doses of efficient microorganisms in the physiological and sanitary aspects.