Chás de composto no crescimento de plantas de milho e sorgo expostas ao déficit hídrico e metais pesados

Abstract

Compost teas have been reported as plant biostimulants and/or biofertilizers, improving responses in growth and tolerance to biotic and abiotic stresses, with abiotic stresses still little explored in the literature. In this context, the objectives of this work were: 1) to elucidate, through a meta-analysis, the potential to induce tolerance to abiotic stresses that compost and vermicompost teas can provide; and 2) verify the effects of two compost teas on the initial growth of maize and sorghum and on the tolerance of both species to water deficit, the presence of lead (Pb) and aluminum (Al). For this, two composting processes were carried out that differed in relation to nitrogen sources: one completely plant-based, and the other using cattle manure. The composts obtained served as raw material for extracting teas (respectively, PCT: plants compost tea, and CMCT: cattle manure compost tea). Four experiments were carried out for each species, totaling the following data sets: 1) action of compost teas on maize and sorghum; 2) action of compost teas on maize and sorghum under water deficit; 3) action of compost teas on maize and sorghum under Pb stress; and 4) action of compost teas on maize and sorghum under Al stress. The methodology used and the statistical analyzes are detailed in the articles contained in this Thesis. The meta-analysis demonstrated that compost teas and vermicompost teas can be applied as tolerance-inducers to abiotic stresses in plants, and their mechanisms of action involve the modulation of enzymatic antioxidant metabolism, enhancing photosynthetic metabolism, homeostasis of potassium and sodium, growth stimulation and, consequently, the increase in productivity. Furthermore, the compost teas tested showed biostimulant activity on maize and sorghum, by stimulating initial growth, root morphology and architecture, and mitigating water deficit and stress caused by Pb and Al.