Banca de DEFESA: KIMBERLY CHRISTINA MARQUES DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : KIMBERLY CHRISTINA MARQUES DA SILVA
DATE: 26/02/2026
TIME: 09:00
LOCAL: Sala 39
TITLE:

Modes of Action and Biostimuli Differentiated by the Type of Humic Substance and Route of Application in Rice Plants (Oryza Sativa L.)

KEY WORDS:

Bioactivity. Gene Expression. Plant Production. Supramolecular.

PAGES: 95
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Numerous approaches have been developed to evaluate the effects of foliar and root application of humic acids (HA) and fulvic acids (FA), extracted from vermicompost, on the productivity of rice (Oryza sativa L.). Humic substances play a fundamental role in improving the physicochemical properties, as well as directly influencing plant metabolism and growth. Among the different sources of humic substances, those extracted from vermicompost stand out as the most widely used and promising, representing a viable alternative for sustainable plant production. Understanding the structure-property-function relationships of these substances is essential to elucidate the mechanisms by which they modulate physiological and genetic processes in plants. Humic and fulvic acids have proven effective in regulating physiological, genetic, and metabolic responses, promoting improvements in nutrient absorption and root development. However, gaps remain regarding the interaction of these substances with different application routes and timing throughout the crop cycle. In this context, this study aimed to evaluate the effects of applying humic and fulvic acids (HA) and rice foliar (LF), investigating their influence on morphological, production and genetic parameters. Chapter I presents the elemental, spectroscopic, and morphological characterization of humic and fulvic acids extracted from vermicompost, and Chapter II discusses the responses to growth modulation and root architecture, and gene regulation of rice by humic and fulvic acids as a function of the application route and timing. The results demonstrated that LF promoted faster physiological responses, reflected in initial increases in plant growth and biomass, especially when applied via foliar application, due to its more heterogeneous and reactive structures. In contrast, AH induced greater initial gene activation, mainly via the root system, associated with the modulation of pathways related to nitrogen metabolism, redox signaling, ion transport, and hormonal regulation, although with later morphological responses. Root application favored root system development, while foliar application intensified shoot growth. The results indicate that the chemical structure of the humic fractions defines their modes of action, determining differentiated responses in rice growth and gene regulation. Thus, these results contributed to deepening the knowledge about the mechanisms of action of these substances, broadening the understanding of the modes of action of these biostimulants in rice development.

COMMITTEE MEMBERS:
Presidente - 1399485 - ANDRES CALDERIN GARCIA
Interno - 387406 - RICARDO LUIZ LOURO BERBARA
Externo à Instituição - DAVID VILAS BOAS DE CAMPOS