Fitorreguladores na produção e características físico-químicas de azeitonas e azeites 'Arbequina' no Rio Grande do Sul, Brasil

Abstract

The cultivation of olive trees has experienced significant expansion in Brazil, particularly in regions where soil and climatic conditions favor their development and productivity. However, climatic variability plays a decisive role in the yield and quality of the fruits and the extracted olive oil, making it essential to investigate factors that may mitigate such impacts. In this context, two independent studies were conducted, and their results were systematized in the form of scientific articles. The first study aimed to evaluate the isolated effects of thidiazuron (TDZ) and aminoethoxyvinylglycine (AVG) on the productivity and fruit quality of the 'Arbequina' cultivar in the municipality of Pinheiro Machado, RS. The second study focused on evaluating olives and olive oils from the cv. Arbequina, harvested at the same phenological stage in different locations in the state of Rio Grande do Sul: Canguçu, Dom Pedrito, Encruzilhada do Sul, and Vacaria, during the 2024 harvest. In the first study, productive and biometric parameters were analyzed, including average yield per plant (kg plant⁻¹), estimated productivity (kg ha⁻¹), average fruit mass (g), as well as their morphometric dimensions (length and diameter, in mm). The results indicated that the application of TDZ, regardless of concentration, did not promote increases in olive tree productivity. Additionally, the application of AVG resulted in reduced production as its concentration increased. Although differences were observed in the physical parameters of fruits treated with TDZ and AVG, these variations did not show a significant impact on the evaluated productivity indices. The second study aimed to assess the composition of olives and olive oil obtained from these samples, evaluating quality and bioactivity parameters. The olives were analyzed for total phenolic content, antioxidant activity (DPPH), and fruit ripening index. The extracted olive oil was analyzed for free acidity (expressed as % oleic acid), peroxide index (mEq O₂/kg), specific ultraviolet (UV) extinction at 232 nm and 270 nm, Delta K, and total phenolic content (mg/kg). The results showed that the ripening index was uniform across locations (2.0), while altitude and precipitation exhibited differences. The altitudes were: Canguçu (386 m), Dom Pedrito (141 m), Encruzilhada do Sul (432 m), and Vacaria (937 m). Precipitation in the pre-harvest week was 0.8 mm, 8.8 mm, 0.0 mm, and 31.8 mm, respectively. Total phenolic content in the fruits ranged from 705.76 to 423.76 mg GAE/100 g, and antioxidant activity varied from 0.3902 to 0.3713 μmol TE/g. Conditions of high altitude and pre-harvest rainfall negatively affected olive oil quality (Vacaria/RS), while Encruzilhada do Sul showed the best performance due to its moderate altitude and absence of rain. All evaluated oils were classified as extra virgin.