Relações entre microrganismos, bioindicadores de qualidade e estrutura da comunidade microbiana em solos sob sistemas de integração lavoura-pecuária
Nenhuma Miniatura disponível
Data
2017-04-27
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
Crop-livestock integration (CLI) is an agricultural system of ecological intensification well accepted by Brazilian farmers, for whom there are doubts about the management of root diseases. This research work is comprised by three studies carried out in CLI fields implemented in 2000, with crop rotations involving maize, upland rice, soybean and brachiaria (Urochloa brizantha). The first study assessed the relationships between soil quality indicators [microbial biomass carbon and nitrogen (C-BM, N-BM), soil basal respiration (RBS), metabolic coefficient (qCO2) and total enzyme activity (AET)], and soil moisture with the population of soil fungi (Fusarium solani and F. oxysporum species complexes, Trichoderma spp. and Rhizoctonia spp.). Redundancy analysis demonstrated the increase of the inoculum density of F. oxysporum in higher N-BM and RBS, and its negative correlation with Trichoderma spp. The increase of F. solani was correlated to higher qCO2 and RBS, and with lower C-BM. The highest densities of Trichoderma spp. were linked with higher soil moisture. These results indicate that practices that stimulate C-BM and decrease RBS can be adopted for the management of the Fusarium species complex. The second essay investigated the interrelations between soilborne fungi (F. solani, F. oxysporum, Rhizoctonia spp., Trichoderma spp. and arbuscular mycorrhizal fungi.), actinomycetes, and nematodes (Pratylenchus spp. and free-living nematodes) in 2015 and 2016. Two distinct clusters were formed by the community of microorganisms according to the presence of irrigation or differences in the rotations under CLI. Rotations that increase pathogens such as the root-lesion nematode Pratylenchus spp. also stimulate their potential antagonists such as arbuscular mycorrhizal fungi. Principal components analysis determined the F. solani and F. oxysporum species complex are the main causes of variation affected by CLI management in 2015 and 2016. No evidence was found that the rotations lead to the suppression of any pathogen and, according to PERMANOVA, it was observed that the abundance of microorganisms under study is affected at by crop sequences, even after 15 years of CLI implantation. The third study evaluated in 2015 and 2016 the structural changes of fungal and bacterial communities in the same CLI system, through T-RFLP analysis. Bacterial and fungal communities showed a clear dissimilarity between the anthropic environments (irrigated and rainfed CLI), and the adjacent native vegetation area. The fungal community was more sensitive to crop rotations within the rainfed or irrigated environments, while bacteria appeared to be resilient to the shifts of cultivated species. In conclusion, the management of CLI systems in the Brazilian Cerrado over 15 years altered the composition of the microbial community and the relationships between root pathogens, antagonists and soil quality indicators. These responses from the microbial community may be useful to advice crop management in fields under CLI, including the management of root diseases.
Descrição
Citação
GOULART, Priscila Ferreira dos Santos. Relações entre microrganismos, bioindicadores de qualidade e estrutura da comunidade microbiana em solos sob sistemas de integração lavoura-pecuária. 2017. 115 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2017.