Banca de DEFESA: LEANDRO REIS COSTA SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LEANDRO REIS COSTA SANTOS
DATE: 30/03/2022
TIME: 14:00
LOCAL: Defesa remota pelo Google Meet
TITLE:

Variations in nitrogen fixation and endophytic bacterial communities in maize genotypes recommended for cultivation in different soil and climatic conditions

KEY WORDS:

Zea mays L., C4 photosynthetic system; next-generation sequencing; Genetical diversity.

PAGES: 108
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Maize is the main cereal produced in Brazil and in the world, being widely used in human and animal food and in the production of biofuels. Biological nitrogen fixation (BNF) and the use of processes mediated by the endophytic communities of this grass are alternatives for the availability of nutrients and other mechanisms to promote plant growth, with the potential to promote higher yields and economy of inputs dependent on fossil energy. Due to its social and economic importance, there is a wide availability of maize genotypes, recommended for the different growing regions. The objective of this work was to estimate the BNF and the qualitative composition of the communities of endophytic bacteria of maize genotypes, identified as the most productive for the conditions of the Brazilian Northeast, cultivated in different edaphoclimatic conditions. Three field experiments were carried out in the municipalities of Araripina, Serra Talhada and Vitória de Santo Antão, in the state of Pernambuco, all without the use of bacterial inoculants. In the semiarid region, the genotypes BRS 4107, BRS 5026, BRS 4105, POTIGUAR, COPACABANA, BR 5036, BR 5037, MUCURIPE, IPR 164 and BR 2121 QPM were cultivated. In Zona da Mata, the genotypes were 1L1411, 1P2224, DKB 390 PRO 2, 1F640, DKB 310 PRO 2, CMS 36, SÃO JOÃO, BRS 3042, 1P2227 and 1M1804. Despite the difficulties in selecting reference plants to estimate BNF in grasses, significant differences were observed between the isotopic compositions of N in the maize leaves and the N in the soil available for the crop (estimated using two different approaches) in two experimental areas. This result demonstrates that the technique of natural abundance of 15N can indicate maize genotypes with the greatest potential to benefit from BNF, useful information in plant breeding programs for the crop. Thus, it was verified that different corn genotypes recommended for higher productivity for the Northeast region of Brazil absorb N fixed by diazotrophs naturally established in the rhizosphere or endophytically. The genotypes BR 5036 and BRS 4105, in the Semiarid region, and DKB 310 PRO2 and 1F640, in the Zona da Mata, presented the highest proportion of fixed N. However, the ability to accumulate fixed N of the genotypes tested in the semiarid region is strongly impacted by soil and climate conditions and water stress, which restricted BNF in Serra Talhada. The communities of endophytic bacteria of uninoculated corn plants harbor genera with reports of presenting mechanisms that promote plant growth, such as FBN, production of phytohormones, suppression of phytopathogens, tolerance to abiotic factors and solubilization of nutrients. The maize genotype has no significant influence on the composition of the endophytic microbiome, but the place of cultivation does. The roots have a greater diversity of endophytic bacteria, probably due to the compounds excreted by it. The genera of endophytic bacteria with the highest occurrence in corn roots and stalks are Leifsonia, Bacillus, Klebsiella and Streptomyces, followed by Bradyhizobium, Paenibacillus, Enterobacter and Sphingomonas, regardless of the plant genotype or the soil and climate conditions of the place of cultivation. Pseudomonas, Acinetobacter, Geobacillus, Enterococcus and Mycobacterium occurred in smaller amounts, always with greater relative abundance in the roots. The results of this work emphasize the importance of further studies on the communities of bacteria in association with corn, the processes mediated by them and their interactions with the plant genotype and cultivation conditions, which will be fundamental for the establishment of managements that include techniques biotechnological tools to increase and sustain this important crop.

BANKING MEMBERS:
Externo à Instituição - CAIO AUGUSTO YOSHIURA
Presidente - 457.055.504-72 - ANA DOLORES SANTIAGO DE FREITAS - UFRPE
Externa à Instituição - CAROLINA ETIENNE DE ROSALIA E SILVA SANTOS - UFRPE
Externo à Instituição - EVERARDO VALADARES DE SA BARRETO - UFPE
Interna - 1929733 - GISELLE GOMES MONTEIRO FRACETTO