Eficácia de fungicidas químicos e biológico no tratamento de sementes salvas de cultivares de trigo

Abstract

In Brazil, the Southern Region accounts for more than 80% of the country's wheat production, with Rio Grande do Sul and Paraná States being the largest producers. Although seed quality is essential to improve crop establishment, many producers still tend to save part of the harvested seeds to grow them in the next harvest. As a result, they may have low physiological quality and be contaminated by pathogens such as Fusarium spp., Pyrenophora spp., Pyricularia spp., Cochliobolus spp., Phaeosphaeria spp., among others, which become the primary inoculum for the crop. The aim was to determine the effectiveness of chemical fungicides applied alone and in combination with a biological fungicide for the treatment of saved wheat seeds and their effects on sanity and vigor. The experiment was carried out in a greenhouse and at the Plant Pathology Laboratory at the Universidade Federal da Fronteira Sul, Erechim, RS, Brazil, between June 2024 and February 2025. The experimental design was completely randomized, in a 6 x 8 factorial scheme (cultivars x treatments) and 4 replicates per treatment. The cultivars used were: TBIO Capaz, TBIO Motriz, TBIO Ponteiro, TBIO Trunfo, ORS Senna and ORS Soberano, whose seeds were saved in the 2023 crop season. The treatments applied to the seeds were: T1 (control without fungicides); T2 (pyraclostrobin + thiophanate methyl + fipronil); T3 (fluxapyroxad); T4 (thiophanate methyl + fluazinam); T5 (Bacillus amyloliquefaciens - Ba + Bacillus velezensis - Bv + Bacillus thuringiensis - Bt); T6 (pyraclostrobin + thiophanate methyl + fipronil + Ba + Bv + Bt); T7 (fluxapyroxad + Ba + Bv + Bt); and T8 (thiophanate methyl + fluazinam + Ba + Bv + Bt). It was evaluated: hectoliter weight; moisture content; electrical conductivity of the seeds; first germination count; germination; sanity; seedling length in the laboratory and in a greenhouse; and seedling emergence in a greenhouse. The results showed that there are differences in the responses of vigor, germination, seeds sanity, and seedling emergence according to each cultivar. However, chemical treatments associated with biological treatments based on Bacillus spp., especially T8, provided better performances in relation to the first count, germination and seedling length. For seeds sanity, T4 was more efficient in controlling Fusarium spp., while T8 stood out in controlling Aspergillus spp. Therefore, the use of chemical fungicides associated with biologicals in the treatment of saved seeds of wheat cultivars improves their physiological and sanitary quality.