Banca de DEFESA: NATHÁLIA VIRGÍNIA DA SILVA RIBEIRO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : NATHÁLIA VIRGÍNIA DA SILVA RIBEIRO
DATA : 25/09/2018
HORA: 09:00
LOCAL: Programa de Pos-graduação Fitotecnia
TÍTULO:
Study of the functional activity of diazotrophic bacteria and the potential of use as biofertilizer in Brachiaria genotypes
PALAVRAS-CHAVES:
Biological nitrogen fixation, diversity, Brachiaria, bacterial inoculation, plant growth promoting bacteria.
PÁGINAS: 120
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitotecnia
ESPECIALIDADE: Fisiologia de Plantas Cultivadas
RESUMO:
Bacteria of the genus Azospirillum and Nitrospirillum can endofitically colonize Brachiaria species and contribute to the development of the culture through the biological nitrogen fixation (BNF) process, production of plant growth hormones and bioavailability of nutrients. The objective of this study was to evaluate the occurrence and diversity of endophytic bacteria of the genera Azospirillum and Nitrospirillum in 20 genotypes of Brachiaria, and the functional capacity of FBN strains, auxin production, siderophores production, cellulolytic capacity and solubilization of phosphate and zinc. Plant samples were collected at the Germoplasma Active Bank (BAG) of the National Center for Cattle Research (CNPGC) in May 2015. The occurrence of Azospirillum spp. and Nitrospirillum amazonense in the rhizospheric soil, roots with and without disinfestation were analyzed by counting by the Most Probable Number (MPN) method in semi-solid medium NFb and LGI followed by the isolation of the diazotrophic bacteria. In general, the population size of viable diazotrophic bacteria ranged from 102 to 108 bacteria per gram of fresh tissue. In total, 222 isolates were obtained, of which, two hundred and sixteen isolates had the 16S RNAr subunit sequenced and taxonomically identified. A bacterial diversity was observed, even using semi-selective media for Azospirillum and Nitrospirillum. Of the 222 isolates, 39,2% of them capable of solubilizing inorganic phosphate and 9,5% of Zn, 32,4% presented cellulolytic capacity, 84,2% produced siderophores and 18,5% of indole compounds under in vitro conditions and presence of the nifH gene was observed in 85,14% of the isolates. In greenhouse studies, nitrogen treatment showed the highest yields of dry mass and accumulated N of the plant in all genotypes, with the exception of Tupi. Among the inoculated treatments, the results showed that there is a significant difference in relation to the control in the biomass production and in the N accumulation of the plant in the twelve Brachiaria genotypes. The strains considered promising for each Brachiaria genotype showed yields equivalent to a minimum of 70 kg N ha-1. Therefore, the use of inoculants with these bacteria may be an alternative in the reduction of nitrogen fertilizer in order to reduce costs in pastures.
MEMBROS DA BANCA:
Presidente - 538.864.458-87 - JOSE IVO BALDANI - UFRRJ
Interno - 058.898.198-28 - SEGUNDO SACRAMENTO URQUIAGA CABALLERO - USP
Externo à Instituição - SILVIA REGINA GOI - UFRRJ
Externo à Instituição - MARCIA REED RODRIGUES COELHO - EMBRAPA
Externo à Instituição - ANDRÉ LUIZ MARTINEZ DE OLIVEIRA - UEFS