Banca de DEFESA: GUSTAVO SOUZA LIMA SANT'ANNA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : GUSTAVO SOUZA LIMA SANT'ANNA
DATA : 17/04/2020
HORA: 09:00
LOCAL: videoconferência web RNP
TÍTULO:

Microbial diversity in soils cultivated with cover crops under no-tillage and conventional tillage in organic production unit

PALAVRAS-CHAVES:

Microbial diversity.rrsgene. Next-generation Sequencing.

PÁGINAS: 70
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
RESUMO:

No-Tillage (NT) has been adopted as an alternative to the conventional Tillage (CT) for a betteragro-ecosystem conservation. In this context, cover crops are essential for the production of litter and release of nutrients in the soil, which directly influences microbial populations. Thus, the objective of this work was to evaluate the bacterial diversity of soils under CT and NT with different cover plants in an organic production unit in Seropedica, Rio de Janeiro, Brazil. The Experiment I was conducted in a randomized block design with 2 plots (CT and NT) with 4 replications. The black oats were sown in a total area and, when the flowering was reached, the oats were incorporated or maintained on the soil surface. Then corn was sown in all plots. Soil sampleswerecollected in the initial time, after black oats cultivation and after corn harvest at a depth of 0-5 cm. The Experiment II was conducted sequentially in a factorial design (2 x 6) with subdivided plots, with 2 plots of CT and NT, 6 subplots with cover crops:pearl millet, sunn hemp, jack bean, cocktail 1 and cocktail 2, using 100 and 50 % of the recommended amount of seeds for each species, respectively, and spontaneous plants, and 4 repetitions. Soil samples were collected after cultivation of cover plants at a depth of 0-5 cm. The chemical characterization and soil DNA extraction was carried out for sequencing the Bacteria rrs gene. In experiment I, between the initial characterization and corn in CT and NT, an increase in the phosphorus content and a decrease in carbon, an increase in the diversity indexes and a change in the bacterial composition was observed, mainly in relation to the phylum candidate division WPS-1 which had an increased relative abundance and the Micrococcaceae family which showed a decrease in its relative abundance after conversion to agricultural area. After corn harvest, potassium was higher in CT and unclassified families of the class Spartobacteria and Chitinophagaceae were more abundant in NT. In experiment II, the different cover crops did not promote changes in the chemical attributes of the soil. The spontaneous plants promoted an increase in microbial diversity in relation to sunn hemp. Jack beans and cocktails 1 and 2 promoted higher relative abundance of the Sphingomonadaceae and Bradyrhyzobiacae families, while spontaneous plants resulted in a higher relative abundance of unclassified bacteria and the Planctomycetaceae family. The NT in relation to the CT showed higher levels of organic carbon and phosphorus, and there was change in the bacterial community with an increase in the relative abundance of Spartobacteria unclassified families and Flavobacteriaceae and a decrease in the relative abundance of Gaiellaceae and Gemmatimonadaceae families. It is expected the effects of the different cover crops in CT and NT on the physical-chemical characteristics and on the bacterial communities of the soils will be more evidentin the next cycles, since, until now, their effects have been evaluated after cultivation.

MEMBROS DA BANCA:
Presidente - 1815763 - IRENE DA SILVA COELHO
Externa à Instituição - MARCIA REED RODRIGUES COELHO - EMBRAPA
Externo ao Programa - 2136627 - NIVALDO SCHULTZ