Impacto do isotiocianato de alila sobre a comunidade microbiana e indicadores microbiológicos do solo

• Autor(a) principal: Aguiar, Naylor Daniel da Costa
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1044
• topic: Óleo essencial de mostarda; Isotiocianatos; Atividade microbiana; Comunidade fúngica; Comunidade bacteriana; Essential oil of mustard; Isothiocyanates; Microbial activity; Community fungal; Bacterial Community; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA

The use of chemicals, synthetic or substance originated from natural plant, to control nematodes is essential for the infested crop management or for the production of healthy seedlings. The recommendation is that the application of these products is only authorized when it is demonstrated that they do not result in damage to the ecosystem sustainability. Studies about the impact of these products on the soil microbial community are required. The hypothesis that the soil microbial diversity is restored and ensures the natural homeostasis of the soil after allyl isothiocyanate (ITCA) application was tested in this study. The studied variables were defined as: three different soil textures, clayey to sandy, doses and timing of soil fumigation with ITCA. The impact of the fumigant ITCA on the soil microbial, evaluated by the measurement of microbial and enzymatic activities and through genetic diversity of fungi, bacteria and nematodes analysis in the soil for one month after the allyl isothiocyanate application, showed that in the three textures of soil there was a reduction of the microbial biomass carbon (MBC) and also in the activity of the acid phosphatase enzyme, and an increase in the basic phosphatase activity. The β-glucosidase activity after the ITCA (p ≤ 0.05) increased in sandy and medium textured soils, and was reduced in the clayey soil, while potential nitrification and respiration were reduced (p ≤ 0.05) in the sandy soil texture and increased in the clayey and medium soils. The soil bacterial community was not affected by ITCA application, as evidenced by the fingerprint and diversity, evenness and richness, but the fungi community exhibited a small disturbance. The ITCA application reduced the soil nematode community (p ≤ 0.05) and the effect of the dosage and treatment time resulted in greater reduction in the microrganisms activity (p ≤ 0.05) when considered the fumigation for 10 days. Fumigation for 10 days caused a reduction in the activity of phosphatases, acid and basic, of the β-glucosidase and carbon biomass (p ≤ 0.05), while the basal respiration was higher at a dosage of 120 mL of ITCA per kilogram of soil, dosage in which nitrification potential rate increased. The fingerprint and indexes of diversity and dominance show that the bacterial and fungus communities in soil were not affected. In one month after ITCA application there was no total activity recovery of the enzymes in the medium and clayey soil texture. The microrganisms respiration increased immediately after ITCA application. Considering that in medium and clayey soils it got back to the natural condition on the fourteenth day, but it did not occur in sandy soils. At 28 days, small changes were seen in bacteria and fungi fingerprint of the soil. There was no loss of fungi and bacteria diversity in the soils treated with ITCA. In general, the use of ITCA for controlling nematodes not affected significantly the activity of fungi and bacteria in the soil, because the impact on the microbial community was low.