Produção e formulação de herbicida por fermentação em estado sólido utilizando o fungo Diaporthe sp.

Abstract

The weed control is accomplished primarily through chemical herbicides. Currently, the use phytotoxins produced by microorganisms are presented as sustainable alternatives. The objective of this study was to produce a herbicide by solid state fermentation (SSF) using the fungus Diaporthe sp. The phytotoxic potential of the fermentation broth was assessed in control of target (Cucumis sativus). The experiments were divided into two steps: i) the fermentation condition for bioherbicide production was assessed. In this step the response was the percentage of damage in leaves of target; ii) evaluation of different formulations containing palm oil, Tween® 80 and Span® 80, in order to increase phytotoxicity. In step 1, the maximum herbicidal activity (1.23% of the leaves had lesions) was obtained at 25°C, moisture content of 50 wt%, supplemented with 10 wt% of corn steep liquor and soybean bran and inoculum density of 15 wt%. In step 2, the formulation containing 8.2 wt% of palm oil, 8.2 wt% of Tween® 80 and Span® 80, resulting in an HLB of 12.8 showed the highest phytotoxicity on the leaves. At this condition, dry weight of target was reduced about 36% in comparison with control. Diaporthe sp. has the potential to produce molecules with herbicidal activity and the use of adjuvants enhances its efficiency in weed control.