Banca de DEFESA: RHAIANA OLIVEIRA DE AVIZ

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: RHAIANA OLIVEIRA DE AVIZ
DATA: 19/01/2026
HORA: 08:00
LOCAL: NÚCLEO DE PÓS-GRADUAÇÃO / CCA
TÍTULO: Soil biological attributes and rhizosphere microbial community of pricklypear cactus inoculated with Bacillus and Paenibacillus
PALAVRAS-CHAVES: Microbial biomass; Microbiome; Nopalea cochenillifera; PGPB; Semiarid; Water deficit.
PÁGINAS: 85
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
RESUMO:

In semiarid regions, drought-tolerant plants such as prickly-pear cactus (family Cactaceae) are essential for sustaining food production for both humans and livestock. However, prolonged droughts intensified by climate change can compromise the growth of this plant. Some bacterial taxa, such as Bacillus and Paenibacillus, are known to colonize the rhizosphere and promote plant growth (PGPB), as well as mitigate the effects of water stress. Nevertheless, little is known about the effects of inoculation in cactus species on microbial biomass, enzymatic activity, and the rhizosphere microbiome under semiarid soil and climatic conditions. In this context, the aim of this doctoral thesis was to investigate the effects of inoculation with Bacillus subtilis and Paenibacillus sp. on two genotypes of prickly pear cactus (Nopalea cochenillifera Salm-Dick), ‘Baiana’ and ‘Doce’, and to evaluate their impacts on biological properties and the rhizosphere microbiome under semiarid edaphoclimatic conditions and water deficit. In Chapters I and II, a field experiment was conducted using a completely randomized design in a split-split plot arrangement (2 × 3 × 2). The main plot factor was plant growth stage (90 and 270 days after planting), the subplot factor was PGPB inoculation (non-inoculated, and inoculated with B. subtilis or Paenibacillus sp.), and the sub-subplot factor consisted of the two cactus genotypes (‘Baiana’ and ‘Doce’). In Chapter I, microbial biomass C, N, and P, as well as enzymatic activities, were evaluated. The results showed that interactions among growth stage, PGPB taxa, and cactus genotypes significantly influenced microbial biomass and enzymatic activity in the rhizosphere, and that combining specific genotypes with B. subtilis can enhance phosphorus availability. In Chapter II, the diversity, composition, and enrichment of rhizosphere bacterial communities were assessed. It was concluded that the rhizosphere microbiome of prickly-pear cactus was shaped primarily by plant growth stage, with key bacterial groups potentially associated with stress tolerance. Chapter III describes a greenhouse experiment arranged in a randomized block design with a 3 × 2 factorial structure. The factors included PGPB inoculation (non-inoculated, inoculated with B. subtilis, or inoculated with Paenibacillus sp.) and two water availability conditions (50% and 25% of soil field capacity). The cactus genotype used was ‘Miúda’ (equivalent to the ‘Doce’ genotype), and the structure, diversity, abundance, and co-occurrence networks of the rhizosphere bacterial community were evaluated. The results showed that water availability significantly altered bacterial community structure, with Actinobacteriota dominating under water deficit and Proteobacteria under well-watered conditions. Additionally, B. subtilis promoted cooperative microbial networks and may potentially enhance drought resilience.

MEMBROS DA BANCA:
Presidente - 2476126 - ADEMIR SERGIO FERREIRA DE ARAUJO
Externo à Instituição - 457.***.***-72 - ANA DOLORES SANTIAGO DE FREITAS - UFRPE
Externo à Instituição - 080.***.***-21 - ARTHUR PRUDÊNCIO DE ARAÚJO PEREIRA - UFC
Externo à Instituição - 127.***.***-34 - CAROLINA ETIENNE DE ROSALIA E SILVA SANTOS - UFRPE
Interno - 1342777 - RAFAEL DE SOUZA MIRANDA