Desenvolvimento de um bioherbicida a partir de metabólitos de phoma sp. para o manejo de plantas daninhas

Abstract

The weeds are one of the main problems faced by the farmers, because such weeds are responsible for a significant amount of the agricultural losses. The key control method is the chemical with use of herbicides. Although efficient when used in doses not recommended or inadequate form have promoted environmental contamination, of animal, intoxication of farmers, residues in food, appearance of resistant biotopes, among others. Looking for alternatives of control less aggressive, the utilization of a formulated product from microorganisms, mainly fungi, becomes an important tool into the area of plant protection and the biological control. In this way, the present work had as objective to concentrate and formulate a bioherbicide based on Phoma sp. with effect on bioindicated plants and weeds. The experiments were divided in 3 stages. In the 1° stage, it was realized the purification and concentration of the fermented broth throughout polymeric membranes, in this stage to analyze the potential phytotoxic was utilized leafs from Cucumis sativus. In the 2° stage, was utilized the best condition of the 1° stage to evaluate different formulations containing palm oil, Span®80 and Tween®80, with the objective of increasing the phytoxicity, applying the products in post-emergence on C. sativus. The 3° stage evaluated the phytotoxity in weeds with pre and post-emergence. In pre-emergence, the tests realized were in BOD chamber and in substrate of an species called Amaranthus retroflexus, for this, it was utilized the best condition of the 1° stage. In the post-emergence it was utilized the formulation than presented the best result within the 2° stage and the conditions with different oil concentrations, being the tests performed in three species: A. retroflexus, Bidens pilosa and Conyza canadensis. The results obtained for a primary evaluation demonstrated that the molecules concentration was efficient in 30% of the retained broth, presenting a greater effect in the leaf detected from C. sativus. In the 2° stage, the formulation 6, that presents for 10g of formulated 0,82g oil palm, 0,0576g Span 80, 0,2224g Tween 80 and 8,9g of cald, presented a higher phytotoxity in C. sativus. In the 3° stage the application in pre-emergence of broth retained in 30% did not allow to occur the germination of A. retroflexus in both BOD and substrate. In the post-emergence, the formulation 6 presented difference of the formulation 3 and 15 with higher phytotoxic effect in weeds, highlighting more for the A. retroflexus. Phoma sp. presents bioherbicide action in pre-emergence and post-emergence and the addition of an adjuvant for the secondary metabolic resulted in a better action of them on the tested species.