Cytokinin- and Auxin-Based Plant Growth Regulators (PGRs) are commonly employed to increase fruit size due to their ability to modulate cellular structure. This study aimed to evaluate the effects of different PGR application protocols on histological parameters, yield components, and fruit quality in ‘Maxi Gala’ apple. The experiments were carried out under humid subtropical conditions of southern Brazil across two growing seasons (2021/22 and 2022/23), allowing comparison of treatment performance under distinct climatic patterns. Data from common treatments were combined across years for integrated analysis. The PGRs used included 6-benzyladenine (BA) as a cytokinin source; naphthalene acetic acid (NAA) as an auxin source; and tryptophan, a precursor of auxin biosynthesis. PGRs were applied in various combinations and concentrations between 10 days after dormancy break (BBCH 01) and fruit diameters of 25–27 mm (BBCH 74), following a randomized block design with four replicates of twelve trees each. The multivariate analysis of treatments was performed using Principal Component Analysis (PCA). Additionally, an analysis of variance was performed for flesh firmness loss, with means compared using Tukey’s test (p < 0.05). PGRs significantly influenced only the histological parameters of the fruit flesh tissues. BA and tryptophan had the greatest effects on cell size and cell number in the fruit flesh, respectively, both reducing intercellular spaces. Tryptophan was associated with a higher number of smaller cells, whereas NAA promoted larger cell sizes. The combination of BA and NAA, as well as a single application of BA at petal fall, resulted in the highest yield performances and increased the proportion of large fruits. Furthermore, BA enhanced the percentage of red skin coloration and improved flesh firmness during storage.

This study aimed to evaluate the vegetative, productive, and fruit quality parameters of the European pear cultivars ‘Rocha’ and ‘Santa Maria’ under the training systems of Tall Spindle, with branches bent at an angle of 45° (Tall Spindle—45°) and 90° (Tall Spindle—90°) to the leader, and Bi-axis. The evaluation was conducted over the 2016/2017 to 2022/2023 growing seasons in the highland region of southern Brazil. Both Tall Spindle systems significantly improved the yield and productive efficiency compared to the Bi-axis system, with ‘Santa Maria’ showing superior performance under Tall Spindle—90°. While ‘Rocha’ exhibited no significant differences between Tall Spindle systems, it benefited from better vigor control and reduced biennial bearing when trained under the Bi-axis system. Fruit quality parameters were consistent across training systems, indicating Tall Spindle—90° as an optimal choice for productivity and stability in ‘Santa Maria’. These results emphasize the adaptability and efficiency of training systems for pear orchard management.

The objective of this study was to evaluate the agronomic performance of the Geneva® series apple rootstocks G.202, G.213, G.210 and G.814. The rootstock G.202 and G.213 proved to be the less vigorous, being considered dwarfs. For replanting soil, ‘G.210’ was considered an efficient alternative. The ‘G.213’ was the most efficient, in a general point of view, demonstrating that it does not change its yield efficiency and stability characteristics, even under replanting conditions. All rootstocks reached the goal of 120 accumulated tons.ha-1 in Caxias do Sul-RS, highlighting the faster financial return to the growers. ‘G.213’ has higher soluble solids content, indicating the possibility of an earlier harvesting. It is concluded that the G.210 and G. 213 rootstocks are good options for the areas evaluated, under replanting conditions, mainly G.213 for more dense systems and G.210 for areas under extreme replanting conditions.

Chemical thinning of apple trees becomes less reliable once fruit exceed 10 mm in diameter. This study evaluated the efficiency of ACC (1-aminocyclopropane-1-carboxylic acid) for late thinning of ‘Fuji Mishima’ in two commercial orchards located at the municipality of Vacaria-RS and São Joaquim-SC, in southern Brazil, during the 2020-21 and 2021-22 growing seasons. Treatments included an untreated control, five different ACC doses applied at either 18-20mm or 25 mm fruit diameter, and a Maxcel® protocol at the 10mm fruit stage. In São Joaquim-SC, ACC at 1.00 and 1.25 kg product ha^-1 applied at 18-20 mm fruit diameter produced the lowest fruit per cluster and a higher proportion large and extra-grade fruit category. At 25 mm of fruit diameter, ACC at 1.25 kg ha^-1 and Maxcel® at 4.5 L ha^-1 were the most effective. InVacaria-RS, ACC at 1.25 kg ha^-1 reduced fruit per cluster at both 18-20mm and 25mm fruitsize. The 0.75 kg ha-1 ACC dose at either fruit diameter increased the proportion of category-3 fruit, as did 1.00 kg ha^-1 applied at 25mm fruit diameter. Overall, ACC at 1.00 - 1.25 kg ha^-1 achieved effective late thinning without detrimental effects on yield or harvested fruit quality. These results indicate that ACC is a viablelate-thinning tool for ‘Fuji Mishima’ under the edaphoclimatic conditions of southern Brazil,during the 2020-21 and 2021-22 growing season.

Plant growth regulators (PGRs) such as aminoethoxyvinylglycine (AVG), 1-methylcyclopropene (1-MCP), and thidiazuron (TDZ) are widely used to improve fruit set and quality in stone fruits. This study evaluated the effects of these PGRs on fruit set, yield performance, and fruit quality parameters of the Japanese plum cultivar ‘Leticia’ under the edaphoclimatic conditions of the highland region of southern Brazil during the 2021/22 and 2022/23 growing seasons. The treatments (AVG, MCP, and TDZ) were applied in full bloom in a randomized complete block design with four replications, and the data from both seasons were analyzed by principal component analysis (PCA). All PGRs significantly affected fruit set, yield performance, and fruit quality parameters. The strongest associations were found 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 1-MCP for yield performance-related trails. Applications of 125 mg L⁻¹ AVG, 21.43 mg L⁻¹ 1-MCP, and 182 mg L⁻¹ TDZ produced fruits with larger diameters and higher fresh weights. The PCA results indicated that TDZ at 182 mg L⁻¹ was closely associated with fruit set and yield performance, suggesting a strong multivariate relationship among these parameters and demonstrating its potential to enhance the productivity of ‘Leticia’ plum under the edaphoclimatic conditions of southern Brazil during the 2021/2022 and 2022/2023 growing seasons.

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.