Banca de DEFESA: BRISA RIBEIRO DE LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRISA RIBEIRO DE LIMA
DATE: 22/07/2021
TIME: 14:00
LOCAL: vídeo conferência
TITLE:

Root growth and nutrient acquisition in rice plants under leaf application of humic substances.

KEY WORDS:

Humic acids, Fulvic acids, Foliar fertilization.

PAGES: 80
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

The mechanisms of action of HS biostimulants have not been completely elucidated, but scientific evidence points to effects on hormonal signaling pathways or those dependent on oxygen species, launching in promoting plant growth, especially in the root system. A foliar application of HS can be a promising approach, as it allows the isolated study of its direct effects on plants, since when applied in solution, interactions between these substances and nutrients may occur. Therefore, the objective of this work was to evaluate root growth and nutrient acquisition in rice plants submitted to foliar application of humic substances. Humic fractions were completed with vermicompost and humic acids and fulvic acids were purified and characterized by infrared spectroscopy and solid state nuclear magnetic resonance. Tests were developed to determine the best foliar application protocol, to determine the response time of plants to application, the use of surfactant in the applied solution, dose-response curve for foliar and root application. For all the tests mentioned above, the accumulation of root and shoot biomass and several variables of the morphology of the root system of the plants were evaluated. Tests were carried out to evaluate the nutrient absorption capacity, as well as the expression of genes associated with the nutrient absorption process. A trial was also carried out until the end of the rice crop cycle to evaluate the effect of HS on phenotypic variables and grain yield. The spectral analyzes for the characterization of humic substances, point out many similarities between the HA and FA, these vibrations of the same corresponding groups. The HA carbon types were predominantly aliphatic and oxygenated aliphatic, with 80.7% aliphaticity. It was observed that at 7 days after application, the fresh mass of aerial part, root and total was higher only for HA foliar application and lower for HA + Surfactant. At this time of collection, the results pointed to an increase in root dry mass with the use of HA. It is recommended that the foliar application of HA and FA should be carried out without the use of surfactant at 40 mg L^-1 of HA and 400 mg L^-1 of FA. A root application of HA must be performed with 100 mg L^-1 and of FA with 20 mg L^-1. Such foliar and root applications increased the content and content of different nutrients and consequently the expression of OsNRT2.1, OsA7, OsPT9.1, OsIRT1 and OsTIP1.2. Positive effects of foliar application of humic substances on grain yield and filling were also observed. Based on an offered protocol, the foliar spraying of humic and fulvic acids promotes beneficial effects to the plants. These positive aspects are the result of changes in root morphology and nutrient uptake, through stimuli from genes associated with the absorption of different nutrients. SHs sprayed on leaves can improve biomass production and nutritional quality of rice.

BANKING MEMBERS:
Externo à Instituição - LEONARDO BARROS DOBBSS - UFVJM
Externo à Instituição - CARLOS ALBERTO SILVA - UFLA
Interno - 2626406 - LEANDRO AZEVEDO SANTOS