Banca de DEFESA: LAIZA SANTOS DAGNAISSER

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LAIZA SANTOS DAGNAISSER
DATE: 24/05/2023
TIME: 08:00
LOCAL: Online
TITLE:

Evaluation of the use of microalgae biomass cultivated in cattle wastewater for arugula (Eruca vesicaria (L.) Cav.) production. 

KEY WORDS:

Biofertilizer; horticulture; organic cattle farming; CO₂ biofixation.

PAGES: 114
BIG AREA: Ciências Agrárias
AREA: Engenharia Agrícola
SUBÁREA: Engenharia de Água e Solo
SPECIALTY: Conservação de Solo e Água
SUMMARY:

Microalgae have been studied in recent years due to their biotechnological potential. The cultivation of microalgae in wastewater can result in the production of a biofertilizer for agricultural crops. Microalgae biofertilizer is the biomass of microalgae that, after being mineralized, can provide nutrients for plants. The application of microalgae biomass as a biofertilizer for horticultural production is one of the possible uses of this bioproduct. The main objective of the present work was to evaluate the use of microalgae biomass cultivated in organic cattle wastewater (CW) as biofertilizer for cultivation of Eruca vesicaria (L.) Cav. This dissertation was organized into two chapters to address the objectives of each stage of the research. The first chapter addressed the objective of produce, in CW, microalgae Arthrospira platensis DHR 20 (Spirulina) with compatible physical-chemical and microbiological characteristics for use as liquid biofertilizer. The rate of CO₂ biofixation in the microalgae cultivation process was also obtained. The CW was bioremediated with microalgae in column photobioreactors adapted in 2L polyethylene terephthalate (PET) bottles (FBR). The characterization of the CW and microalgae biomass was performed by analyzing total macronutrient (N, P, K, Ca, Mg), micronutrients (Zn, Cu, B), Na content, Sodium Adsorption Ratio (SAR), pH, total organic carbon (C) content, C:N ratio, electrical conductivity (EC), and microbiological parameters (thermotolerant coliforms, viable helminth eggs, Salmonella sp.). The second chapter aimed to comparatively evaluate the effect of microalgae nitrogen biofertilizer, from microalgae production in ARB, with only ARB and with conventional nitrogen source (urea) on the development of the shoot and roots of arugula (Eruca vesicaria (L.) Cav.), as well as monitor the microbiological characteristics in the leaves of arugula. The changes in soil chemical properties and soil structure after the experiment were also evaluated.  The experiment consisted of three treatments: T1 - Control, with application of conventional nitrogen source (urea); T2 - Calculated dose equivalent to conventional N from CW; T3 - Calculated dose equivalent to conventional N from microalgal biomass biofertilizer. The experimental design was entirely randomized (DIC) with seven repetitions with four seedlings each experimental plot. The main conclusion of this research is that microalgae biomass biofertilizer has nutritional potential for plants, mainly as a source of N and K, and as a soil conditioner. According to the SAR, the microalgae biofertilizer produced does not present a level of restriction for use on soil. However, the safety of its long-term application is not guaranteed due to the high levels of Na⁺ and K⁺ found in the soil after receiving this treatment. The average of CO₂ biofixation obtained enables the conclusion that the cultivation of the microalga Spirulina in CW presents suitability for the biocapture of this Greenhouse gas (GHG). The seedlings of arugula produced in the three treatments presented similar developmental quality according to Dickson Quality Index (IQD). However, the plants fertilized with urea showed statistically superior performance in height (H), number of leaves (NF), stem diameter (DC), leaf area (AF), and shoot dry mass (MSPA), and higher concentration of N and Na in the leaves compared to T2 and T3. The arugula leaves of the three treatments showed negative results for the presence of thermotolerant coliforms. The evaluation of soil structure after the experiment indicates that microalgae biofertilizer, as well as ARB, can act as a soil conditioner, improving its structural quality when compared to soil fertilized with urea.

COMMITTEE MEMBERS:
Interno - 2131822 - CONAN AYADE SALVADOR
Interno - 1133133 - HENRIQUE VIEIRA DE MENDONCA
Externo à Instituição - DAVID VILAS BOAS DE CAMPOS - EMBRAPA