Qualidade fisiológica e sanitária de sementes de nabo forrageiro tratadas com Trichoderma spp. e fungicidas químicos

Abstract

Forage turnip (Raphanus sativus L. var. oleifera) is a species with multiple purposes of use, as forage, raw material for biorefineries, cover cropping, green manure among others, preceding crops as corn (Zea mays L.) and soybean (Glycine max (L.) Merrill) in the southern region of Brazil. However, as it is characterized as an off-season crop, forage turnip ultimately does not receive adequate phytosanitary management, causing problems even for successor crops, such as the infection of areas with pathogens present in its seeds or remaining in the crop residues. In order to study the physiological and sanitary quality of the forage turnip seeds, the present work was divided into two experiments. The first with the objectives of evaluating if the treatment of forage turnip seeds with products based on Trichoderma applied alone or in association with chemical fungicides based on Thiophanate-methyl with Fluazinam and Metalaxyl-M with Fludioxonil influences the physiological quality of these seeds, in addition to comparing the efficiency of these treatments in controlling pathogens. Vigor, germination and health test using the blotter test method were carried out. It was observed that the treatment of forage turnip seeds does not cause negative effects on vigor and germination, and may even cause an increase in fresh weight and shoot length when there is a combination of chemical fungicides and Trichoderma. Treatments with biological products applied alone or combined with chemicals showed total control over fungi of the genus Sclerotinia and effectiveness in controlling other pathogens associated with seeds. The second experiment aimed to evaluate the physiological quality of the seeds during certain periods in which they were stored after treatment with Trichoderma-based products applied alone or in association with chemical fungicides based on Thiophanate-methyl with Fluazinam and Metalaxyl-M with Fludioxonil, to verify if they influence its viability and vigor. The treated seeds as well as the untreated control were sown in the field after 0, 7, 14 and 21 days of storage, being evaluated by emergence test and fresh and dry weight of plants, with storage also being extended for periods of 40, 60, 80 and 120 days, to then carry out germination and the first count tests in the laboratory. It was found that the seeds, although their physiological quality was reduced throughout the period in which they were stored, remained suitable for commercialization in accordance with legislation, justifying the treatment of forage turnip seeds even when there is a need to store them.