Solarização em microcosmo: efeito de materiais vegetais na sobrevivência de fitopatógenos de solo e na produção de voláteis

Abstract

In addition to Brassicaceae species associated with soil solarization, new materials from plants such as cassava and castor bean have shown potential to control soil phytopathogens. Thus, the present study aimed to verify the effects of incorporation and decomposition of shoot of broccoli, castor bean, and bitter and sweet cassava, associated with solarization in microcosm sets under controlled environment conditions, on the survival of resistance structures from Fusarium oxysporum f. sp. lycopersici Race 2, Macrophomina phaseolina, Rhizoctonia solani AG-4 HGI and Sclerotium rolfsii; and to identify volatile compound(s) released by the decomposition of materials, which could be related to phytopathogen inactivation. As to pathogen survival, four identical assays were installed in the microcosms, with four independent exposure periods (7, 14, 21 and 28 days). To identify volatile compounds, assays were performed under the same survival conditions, but using amber glass bottles and gas chromatography with mass spectrometry (GC-MS) and flame ionization detectors (GC-FID), and adopting the Solid-Phase Microextraction Technique - SPME. The treatments soil+plant materials, over the tested periods, reduced the survival of resistance structures for all fungi. In general, expressive results were found for broccoli and bitter cassava, as well as sweet cassava against S. rolfsii. The identified volatile compounds were from broccoli, castor bean and sweet cassava decomposition. The number of volatile compounds identified for broccoli, castor bean and sweet cassava were 26, 37 and 29, respectively. Positive and negative correlations were detected among some volatile compounds and their mean values and the survival of resistance structures from phytopathogens.