Desempenho agronômico e incidência de doenças em cultivares de soja provenientes de sementes salvas e certificadas

Abstract

The objective of this work was to evaluate the efficacy of appropriate management of soybean seeds, for obtainment greater tolerance to diseases and production of grains. Were evaluated two lots of soybean seeds (NS 5445 IPRO and BMX Ativa), with saved and certified provenance, associated or not with the application of fungicides, sown in two agricultural years (2015/16 e 2016/17) at the experimental area in the Federal University of Fronteira Sul, Campus Erechim, RS. The experiment was conducted in a completely randomized design, organized in scheme factorial 2 x 2 (grow crops; origination) to the laboratory, and in scheme factorial 2 x 2 x 2 (grow crops; origination; with and without fungicide application) to the field, both with four replications. The variables evaluated were: germination and sanity of seeds; incidence of leaves fungal diseases, number of grains per plant and productivity in each treatment. The main fungi identified in the seeds were: Aspergillus sp., Penicillium sp. andFusarium sp. Both the cultivars and provenances presented the minimum germination required for commercialization, but seed of certified provenance stood out as to the vigor. For the variable normal seedlings there was difference significant only in the agricultural year 2016/17, being that the certified provenance for both as cultivars obtained the better results. The best productivity (kg.ha-1) was achieved in the cultivating of certified seeds associated with the use of fungicides in both agricultural years. The yield component thousand grain weight did not differ statistically to the provenance, but, for the cultivar and fungicides applications, there was a significative difference. The number of grains per plant was higher when used certified seeds combined with the application of fungicides. The main diseases found in the two agricultural years were: asian rust, powdery mildew, downy mildew, septoriosis and cercosporiosis. The provenance of seeds lots, in both years evaluated, did not present a significant difference in relation to the incidence of asian rust, powdery mildew and downy mildew, but for septoriosis and cercosporiosis, considered end-of-cycle diseases, there was a statistical difference.