Banca de QUALIFICAÇÃO: MARIA JOSELINA GOMES RIBEIRO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : MARIA JOSELINA GOMES RIBEIRO
DATE: 27/02/2025
TIME: 09:00
LOCAL: Auditório da Pós-graduação em solos
TITLE:

AMAZONIAN RHIZOBACTERIA IMPROVE TOLERANCE TO WATER DEFICIT IN AÇAI SEEDLINGS SUBJECTED TO TWO WATER REGIMES

KEY WORDS:

Euterpe oleracea, native rhizobacteria, morphophysiology, drought.

PAGES: 50
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitossanidade
SPECIALTY: Microbiologia Agrícola
SUMMARY:

The açaí palm tree is native to the Amazon estuary and is of great economic importance in the Amazon region. Brazil is the world's largest producer of the açaí fruit, and the state of Pará accounts for more than 90% of the national production. However, slow initial growth and high sensitivity to water deficit limit seedling production in nurseries and hinder the expansion of commercial plantations. Rhizobacteria-based biostimulants can be used as an efficient strategy to reduce seedling losses, as they promote growth and increase tolerance to the negative effects of water deficit. The objective of the study was to evaluate the morphophysiological and biochemical changes that are related to greater drought tolerance in açaí seedlings subjected to two water regimes and inoculated with the Amazonian rhizobacteria: Serratia sp. (R46) and Pseudomonas fluorescens (R55). The experiment was carried out in a greenhouse in the soil sector of the Federal Rural University of the Amazon - UFRA, in Belém, Pará. The treatments consisted of non-inoculated plants (control) and inoculated with native rhizobacteria: R46 and R55, which were evaluated in two water regimes imposed by irrigation depths of 100% and 50% of field capacity (CC). At 100% CC, seedlings inoculated with R55 increased by 14% in height and 35% in leaf area, and seedlings inoculated with R46 increased by 11% in stem diameter and 8% in root length compared to the control. At 50% CC, seedlings inoculated with R46 increased by 27%, 50%, 31% and 100% in height, stem diameter, leaf area and root volume, respectively, compared to the control. Inoculation with R55 increased total biomass by 32% and with R46 it increased water use efficiency (WUE) by 25% compared to the control at 100%CC water regime. At 50%CC, inoculation with R55 increased shoot biomass and root biomass by 31% and 33%, respectively, compared to the control. Leaf water potential (Ψw) was 35% lower for R46 and 33% for R55 compared to the control at 50%CC. At 50%CC, inoculation with rhizobacteria improved net photosynthesis (A) (68% in R46 and 46% in R55), reduced intercellular CO₂ concentration (Ci) (9% in R46 and 7% in R55) and transpiration (E) (18% in R46 and 25% in R55). Furthermore, it increased instantaneous water use efficiency (A/E) (105% in R46 and 89% in R55) and carboxylation efficiency (A/Ci) (87% in R46 and 56% in R55) compared to the control treatment. Under 100% CC, R46 increased total chlorophylls (SPAD) by 20% and reduced non-photochemical extinction coefficient (NPQ) by 28%. At 50%CC, R55 increased SPAD by 38%, and R46 increased photochemical extinction coefficient (qP) by 71%, while NPQ reduced it by 45% for R55. At 100% CC, R55 increased carotenoids by 79% and flavonoids by 73% compared to the control. At 50% CC, R46 increased carotenoids by 100% and anthocyanins by 32%, while R55 increased xanthophylls by 33%, and R46 promoted a 38% increase in flavonoids compared to the control. Inoculation of native rhizobacteria R46 and R55 alters the morphophysiological and biochemical responses to improve tolerance to water deficit in açaí seedlings. Therefore, Amazonian rhizobacteria can be inserted into the seedling production system to reduce losses in nurseries and increase the availability of seedlings for field use.

COMMITTEE MEMBERS:
Presidente - 1065086 - GLEDSON LUIZ SALGADO DE CASTRO
Externo ao Programa - 1229342 - DALTON DIAS DA SILVA JUNIOR - UFRAExterno ao Programa - ***.193.302-** - WALTER VELLASCO DUARTE SILVESTRE - UFRA
Externo à Instituição - FLÁVIO JOSÉ RODRIGUES CRUZ - IFAP