Banca de DEFESA: JHONATAN MARINS GOULART

Fermented bran compounds: inoculum sources, agronomic efficiency and characterization 
of the microbiome associated with green manures and vegetables grown under organic management. 

Microbiome, organic agriculture, horticulture.

In order to achieve the proposed objectives, the thesis work was structured in four chapters whose studies addressed the management of fertilization with fermented compounds in the agronomic performance of vegetables, as well as the characterization of the microbiome at the rhizospheric level of vegetables and green manures under organic management. In chapter I, the bacterial community associated with the rhizosphere of maize and the bush fabaceous guandu-GU (Cajanus cajan) and tephrosia-TF (Tephrosia sinapou) in monocultures or intercropping was characterized. The experimental design was in randomized blocks arranged in a factorial arrangement 2 (GU and TF) x 3 (monocrop, intercropped with corn in the same planting furrow and intercropped with corn between rows) + 1 (monocrop of corn). Soil samples from the rhizosphere of different species were collected to characterize the predominant bacterial community. In chapter II, the economic and productive balance of a diversified cultivation module of vegetables fertilized with a fermented compost and green manure was carried out. In order to carry out the system balance, all activities carried out in the module were quantified, including fertilization, workforce, acquisition of seedlings, estimation of commercialization and input and output of system nutrients. In chapter III, the chemical, physical-chemical characteristics, nematicide effects and agronomic efficiency of fermented compounds formulated with fabaceous phytomass bran and agro-industrial residues used in the fertilization of biquinho pepper were evaluated. For the evaluation of the compounds, the experimental design was in randomized blocks, in which the treatments were arranged in a factorial arrangement 2 (wheat bran-FT and malt bagasse-BM) x 4 (leaf bran of GU, TF, Flemingia macrophylla-FL and castor bean-FM). The formulations consisted of a mixture of 40% (FT or BM) and 60% (GU, TF, FL or FM). As for the fertilization of the biquinho pepper tree, the experimental design was in randomized blocks in a factorial scheme 4 (compounds with BM) x 5 doses of N (200, 400, 600, 800 and 1200kg N ha-1) + 1 (control without fertilization) . In chapter IV, the characterization of fungal and bacterial communities present in baits previously installed in plant stands under litter and in the rhizosphere of tomato plants submitted to fertilization with compounds derived from inoculation was carried out. At the same time, the phytotechnical components of tomato were determined. A formulation consisting of 40:60 (w/w), respectively BM:FL, was used. For the tomato plant evaluations, the experimental design was in randomized blocks in a 2 x 7 + 1 factorial scheme, in which the levels of the factors consisted of two compounds (fermented and non-fermented), seven sources of inoculum (Embiotic®; microorganisms collected in the module cultivation of vegetables at Fazendinha Agroecológica Km 47; microorganisms collected under litter from bamboo groves; from secondary forest; from eucalyptus, from the leguminous Acacia mangium; without inoculation (water)), plus a control treatment (without fertilization). The results revealed that the most abundant phyla in the experimental area are Actinobacteriota, Proteobacteria and Acidobacteriota corresponding to 68.6% of the total ASVs. The edaphoclimatic characteristics overlap the vegetation cover regarding the relative abundance of phyla, except for Proteobacteria, Acidobacteriota and Bacteriodota. Two groups are obtained according to the multidimensional scaling analysis (MDS): (a) green manures in monoculture and interrow cultivation; and, (b) the others. In this last group are the treatments associated with corn and which received the fermented compost. The total production of the system considering the cultures of economic interest was 14.04, 12.38 and 10.35 Mg of fresh matter, respectively, 2020, 2021 and 2023. The diversified organic vegetable cultivation system is economically viable considering the commercialization scenarios in the carioca circuit of organic fairs and in an agroecological fair of family agriculture in the municipality of Seropédica, generating average net revenue, considering the period from 2020 to 2022, of, respectively, R$ 142,881.78 and R$ 104,991, 58 reais. The workforce, considering an average value in the period from 2020 to 2022, was responsible for 67.07% of the system costs, in which manual weeding represented the highest cost. The partial balance of nutrients was negative for potassium, calcium and magnesium in 2020 and 2021, while in 2022 it was negative only for potassium, generating a deficit of 25.49 kg in the system. It was found that the fermented compound formulated with malt bagasse, regardless of the complementary source, presents agronomic efficiency similar to that derived from wheat bran in terms of nitrogen supply capacity. The phytotechnical components of biquinho pepper expressed the highest yields with the use of fermented compounds formulated with fabaceae phytomass, however, the magnitude of the effect is proportional to the applied dose. The fermented compound containing castor bean bran, in the range of applied doses, showed total or partial toxicity to biquinho pepper plants at dosages greater than 400mg of N dm3. However, the application of this compound significantly reduced the number of galls caused by nematodes at a dosage of 200 mg of N dm3 and provided total control at higher dosages. Tomato fruit production was influenced by fertilization, in which the unfermented compound inoculated with microorganisms collected from eucalyptus litter provided the best performance 306.77 g plant-1. At the bacterial community genus level, Bacillus was abundant in the baits and detected, to a lesser extent, in the different rhizospheres. At the phyla level of the bacterial community, there was a predominance of the phyla Proteobacteria and Firmicutes in the rhizospheric environment and in the different baits, regardless of the source of inoculum. The relative abundance at the genera level of the fungal community present in the baits was distinct and it is noted the absence or reduction in the abundance of genera from the bait to the tomato rhizosphere.