Plant Growth Regulators on ‘Letícia’ Plum Fruit Set, Productive and Fruit Quality Parameters in Southern Brazil

Plant Growth regulators (PGRs) such as aminoethoxyvinylglycine (AVG), 1-methylcyclopropene (MCP), and thidiazuron (TDZ) are widely used to enhance fruit production. The objective of this study was to evaluate the effect of PGRs on fruit set, productive and fruit quality parameters of the plum cultivar 'Leticia' in highland region of southern Brazil, during the 2021/22 and 2022/23 growing seasons. AVG, MCP, and TDZ were applied at full bloom, in a randomized complete block design with four rep-lications. The biennial mean data were subjected to multivariate analysis using princi-pal component analysis. All PGRs affected fruit set and productive and fruit quality parameters. The strongest correlations were observed with 182 mg L⁻¹ TDZ for fruit set, and with 62.5 mg L⁻¹ and 125 mg L⁻¹ AVG and 21.43 mg L⁻¹ MCP for productive param-eters. Applications of 125 mg L⁻¹ AVG, 21.43 mg L⁻¹ MCP, and 182 mg L⁻¹ TDZ induced the development of fruits with larger diameter and higher fresh weight, respectively. The 182 mg L⁻¹ TDZ treatment showed a significant positive correlation with fruit set and productive and fruit quality parameters of the 'Leticia' plum cultivar under the edaphoclimatic conditions of southern Brazil during the 2021/2022 and 2022/2023 grow-ing seasons.