Banca de DEFESA: JEANE FERREIRA DE JESUS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE: JEANE FERREIRA DE JESUS
DATA: 28/06/2024
HORA: 08:30
LOCAL: Google meet (meet.google.com/gix-unfa-hvw)
TÍTULO: SCREENING ALGAE-BASED BIOSTIMULANTS FOR ACTIVATING DEFENSE MECHANISMS AND INCREASED PRODUCTIVITY OF SEMIARID-ADAPTED SOYBEAN UNDER WATER DEFICIT
PALAVRAS-CHAVES: Ascophyllum nodosum, Glycine max; water limitation, yield, plant metabolism, defense pathways.
PÁGINAS: 111
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitotecnia
ESPECIALIDADE: Fisiologia de Plantas Cultivadas
RESUMO:

In the global scenario, climate change has been increasingly recurrent and accompanied by drought episodes, negatively affecting the agricultural yield. This constraint is no different for soybean cultivation, even though producers have access to genetically modified cultivars for different climates, such as rainfed systems in semiarid regions. The seaweed-based biostimulants has shown potential in enhancing the productive parameters and mitigating the water deficit damages in some plant species. However, evidence into how biostimulants alter plant metabolism in semiarid-typical soybean cultivars is still not fully elucidated. Our study was carried out to test the hypothesis that the application of seaweed-based biostimulants modulates the metabolism of semiarid soybean cultivars, promoting increases in productivity and tolerance to water deficit. The hypothesis was tested through the development of two greenhouse experiments. The first one aimed to select the dose and application timing capable of modulating the physiology and increasing soybean yield under well-irrigated conditions. At this stage, foliar application of the Ascophyllum nodosum-based biostimulant was carried out at doses of 0.5, 1.0, and 1.5 L h^-1, either as a single or split application, at different developmental stages of the Extrema soybean cultivar. The data are described in Chapter II. The second experiment aimed to evaluate the efficiency of four commercial formulations in alleviating the drought effects on soybean performance during vegetative stage, investigating growth and biochemical, physiological, and molecular pathways. The data are detailed in Chapter III. Chapter I presents the state of the art with results and investigations about the theme. The data from experiment I, detailed in Chapter II, demonstrated that the A. nodosum-based biostimulant promoted better physiological conditioning and productive responses, depending on dose and application timing. The dose of 1.5 L ha^-1, applied in equal amounts at V4 and R1 stages, was characterized as the most effective, increasing the net photosynthesis, water status, and resulted in a 12% increase in soybean plant productivity. In Chapter III, the finding of experiment II showed that drought drastically reduced photosynthetic pigments, stomatal conductance, transpiration, and increased non-photochemical energy dissipation, leading to severe restrictions in plant growth. The poor performance under drought was associated with greater membrane damage and hydrogen peroxide levels. The data also revealed that the plants activated defense pathways, such as maintaining water status and activating antioxidant enzymes; however, these mechanisms were not effective in neutralizing the stress damage. Under drought, the biostimulants stimulated the accumulation of metabolites involved in defense pathways (4-aminobutyric acid, benzoic acid, shikimic acid, erythronic acid, arabinose, phenylalanine, threonine, among others) and reprogrammed the antioxidant system, but they were ineffective in mitigating the stress effects on plant performance, at least during the studied period. In conclusion, biostimulants formulated with A. nodosum extracts are capable of enhancing the physiological and yield performance of soybean cultivars under well-irrigated conditions but do not mitigate the harmful effects of water deficit on the metabolism and growth of semiarid cultivars. Future research should focus on biostimulant application strategies under stressful conditions, integrating long-term responses with the investigation of productive parameters associated with defense mechanisms.

MEMBROS DA BANCA:
Presidente - 1342777 - RAFAEL DE SOUZA MIRANDA
Interno - 1275725 - ELAINE MARTINS DA COSTA
Externo à Instituição - DANIEL GOMES COELHO - UFV
Externo à Instituição - JOSE HELIO COSTA - UFC