Tratamentos químicos de sementes de girassol associados com Trichoderma harzianum

Abstract

Originally from the Americas, the sunflower has agronomic purposes such as producing oil and grains for human and animal consumption. It presents greater production in the Center-West region of Brazil, and an option in crop rotation in the direct planting system. In commercial production, seed treatment is essential for the speed of initial development and establishment of the plant population. Various forms of seed treatment can be used, whether chemical or biological and associations between the two. To prevent harmful interactions between treatments, there are studies that report the use of polymers. Thus, the response of the sunflower crop to the application of chemical treatments in association with biological treatment with Trichoderma harzianum was evaluated in the region bordering Lake Itaipu in western Paraná. the experiment was conducted in a randomized block design, evaluating the interaction of four seed treatments, namely: chemical fungicide; chemical fungicide + T. harzianum; chemical fungicide + polymer; chemical fungicide + polymer + T. harzianum. The sunflower seed was already treated with a chemical fungicide, therefore, the treatments consisted of isolates and in combination the following active ingredients and quantities were used: industrial chemical fungicide treatment (fludioxonil + metalaxyl - 200 mL p.c. 100 kg-1 of seeds) ; T. harzianum (T. harzianum Rifai, strain ESALQ-1306 5.1011 CFU 100 kg-1 of seeds) and polymer (100 mL p.c. 100 kg-1 of seeds). The variables evaluated were plant height, dry mass of grains per head, stalk diameter, grain productivity, mass of 100 achenes and grain moisture. The data were subjected to analysis of variance and the 5% Tukey test. In the western region of Paraná, high temperatures and low rainfall in the months of March to July hampered the development of sunflowers. The use of polymer in association with any other chemical, biological or both seed treatment demonstrates the lowest values for crop development, specifically for the mass of 100 grains, and the use of the polymer is not recommended. T. harzianum in conditions of high temperatures and low rainfall may have its establishment impaired, as it did not have a positive influence on production components, as reported in other studies using this biological treatment. The combination of fludioxonil + metalaxyl fungicide with T. harzianum can be used to treat seeds with an increase in the mass of 100 grains. There are still few studies on the use of sunflower seed treatment with biofungicides and associations with the same, meaning more studies on the subject are needed.