Banca de DEFESA: SIDNEY DANIEL ARAUJO DA COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : SIDNEY DANIEL ARAUJO DA COSTA
DATE: 19/05/2022
TIME: 14:00
LOCAL: Realizado por videoconferência
TITLE:
KEY WORDS:
PAGES: 77
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUMMARY:

The Marandu grass belonging to the genus Urochloa (Syn Brachiaria) is a forage of greatest importance in Brazil and has a larger and larger planted area. Pasture management in relation to mineral fertilization was often neglected by producers. However, this scenario has been changing the application of mineral capo fertilizer aiming at greater agronomic performance is a reality. Technologies that are being primed with which are enhancing nutrient use efficiency, increased plant growth and possibly improved, are the developed and improved changes to the environment. The use of plant growth-promoting microorganisms is used in grass and has the ability to reduce the demand for macronutrients, increase plant growth and act as a bioagent to control phytopathogens, in addition to providing sustainable production. The objective of this work was to select biostimulants capable of promoting greater nutrient use efficiency, improving the photosynthetic apparatus and providing greater plant growth. The experiment was carried out in a greenhouse at the Federal Rural University of the Amazon (UFRA). Initially, three experiments were carried out independently, evaluating the reductions of nitrogen (N) (experiment 1), phosphorus (P) (experiment 2) and potassium (K) (experiment 3), inoculated or not. The experimental design was completely randomized in a 5 x 3 factorial scheme with five replications. The factors evaluated were: mineral fertilizer rate: 0, 25, 50, 75 and 100% of the recommended dose and inoculation with growth-promoting microorganisms: uninoculated, inoculated with Bacillus subtilis (UFRA-92) and co-inoculated with Trichoderma asperellum composed of isolates (UFRA-06, UFRA-09, UFRA-12 and UFRA-52) and Bacillus subtilis (MIX). The inoculation of the isolates was carried out via irrigation and at 35 days after emergence, biometric parameters were measured: plant height, root length, leaf and root dry mass, and the following were calculated: leaf appearance rate, leaf elongation rate, leaf area. The leaves were collected and analyzed for nitrogen, phosphorus and potassium composition. The nutrient use efficiency was calculated from agronomic efficiency, physiological efficiency, recovery efficiency and nutrient response efficiency. From the best treatment and the best doses of nitrogen, phosphorus and potassium found in the first trial, a new experiment was set up in a greenhouse, using these results. The treatments were: plants not inoculated and fertilized with a reduced dose of NPK (C), plants not inoculated and fertilized with a maximum dose of NPK (C+) and plants co-inoculated with Trichoderma asperellum (UFRA-06, UFRA-09, UFRA-12 and UFRA-52) and Bacillus subtilis and fertilized with a reduced dose of NPK (MIX). The experimental design was completely randomized (DIC) with ten replications. Gas exchange based on CO₂ assimilation (A), instantaneous carboxylation efficiency (A/C_i), stomatal conductance (g_s) and transpiration rate (E) were evaluated. Chlorophyll a fluorescence was determined from the potential activity of photosystem II (PSII) reaction centers (F_v/F_o), photochemical extinction coefficients (qP), electron transfer rate (ETR), effective photochemical efficiency of PSII (F_v'/F_m') and non-photochemical extinction coefficients (qN). The total chlorophyll content was also measured with the aid of the SPAD chlorophyll meter and the content of chlorophyll a (Chla), chlorophyll b (Chlb) and total (Chla + Chlb) was quantified, as well as the quantification of soluble carbohydrates: Glucose, Sucrose, Fructose and Starch. Growth parameters were evaluated from plant height, root length, leaf and root dry mass, and leaf area and leaf elongation rate were calculated. The nutrient content of the leaves was quantified: Nitrogen, Phosphorus and Potassium. The results of this study showed that the interaction between co-inoculation and doses was responsible for increasing leaf area, plant height, elongation rate and leaf appearance for nitrogen and potassium, while for phosphorus the interaction was significant for root dry mass. The isolated effect of inoculation on nitrogen doses provided an increase of 104% in root dry mass, 194% in leaf dry mass, 22% in root length and 11% in leaf elongation rate. In phosphorus doses, the isolated effect of inoculation generated an increase of 119% in root dry mass, 156% in leaf dry mass, 51% in height, 20% in root length and 9.3% for leaf elongation rate. At potassium doses, co-inoculation generated an increase of 117% in root dry mass, 34% in root length, 14% in plant height, 50% in leaf area and 20% in leaf elongation rate. Inoculation and co-inoculation showed significant increases in all indices of efficient use of the nutrient. The nutritional content as a function of co-inoculation generated an increase of 256% in nitrogen content, 280% in phosphorus content and 29% in potassium content. The results also showed that co-inoculation provided increments of 25% in CO2 assimilation, 140% and 53% in instantaneous carboxylation efficiency, 34% in stomatal conductance and 30% in transpiration. The variables calculated in the chlorophyll a flowering and the growth parameters had significant increments from the co-inoculation. As well as the chlorophyll content, which had an increase of 353% in chlorophyll a, 349% in chlorophyll b and 352% in the sum of chlorophylls. The content of soluble carbohydrates also had positive responses due to the microorganisms, which showed an increase of 218% in glucose, 36% in sucrose, 775% in fructose and 178% in starch. The nutritional content of co-inoculated plants had an increase of 324% in nitrogen, 387% in phosphorus and 243% in potassium. It is possible to affirm that the application of biopromoters in a co-inoculated form were responsible for increasing the nutrient use efficiency, improving the photosynthetic apparatus, increasing plant growth, providing greater efficiency in the acquisition of water and nutrients and in the transformation of energy into productive gains. In this sense, it is possible to affirm that the microorganisms used can be used as inoculants in Marandu grass, to provide an activity with reduced impacts on the environment.

BANKING MEMBERS:
Externa à Instituição - ALESSANDRA KEIKO NAKASONE ISHIDA - EMBRAPA
Externo à Instituição - ANTONIO CLEMENTINO DOS SANTOS - UFT
Externo à Instituição - DALTON DIAS DA SILVA JUNIOR - UFAM
Presidente - 1551252 - GISELE BARATA DA SILVA
Interno - 1065086 - GLEDSON LUIZ SALGADO DE CASTRO