In 2019–2020, trials were carried out in both intensive (cultivar Moraiolo) and super-high-density (cultivar Sikitita) young olive orchards to drastically reduce early production and, consequently, accelerate tree growth. Different concentrations of naphthaleneacetic acid (NAA) (0 ppm–control, 20 ppm, 40 ppm, 80 ppm, 160 ppm and 250 ppm) were applied at full bloom (open flowers > 80%), using a shoulder sprayer, and their effects on vegetative growth and reproductive behavior were evaluated, also compared to manually deflowered trees. The treatments with NAA reduced fruit set (down to values close to zero) compared to the control, and the reduction was correlated with the NAA concentration. In particular, 160 ppm virtually eliminated fruit set and thus production in both Moraiolo and Sikitita cultivars. In Moraiolo, 160 ppm NAA and manual deflowering determined similar shoot and trunk growths, which were greater than in control trees. Application of 160 ppm NAA for two consecutive years gave a progressively higher increase in trunk growth compared to the control. In conclusion, in young olive trees, the treatment with 160 ppm NAA at full bloom practically eliminated fruit set and production, with a parallel great increase in vegetative growth. This can be exploited as a powerful technique to accelerate the growth of young olive trees in both intensive and super-high-density orchards, as well as in nurseries. A more rapid transition to the adult stage/size of the trees and to full production of the orchard allows us to anticipate the use of mechanical harvesting and the recovery of the planting investment.

Optimizing planting density is crucial for balancing resource competition, light penetration, and tree productivity in orchard systems. This study investigateed the impact of planting density on the yield and fruit quality of the hazelnut cultivar ‘Tonda Francescana^®’ grafted onto Corylus colurna L. rootstocks. The research aimed to assess how different planting densities influenced light penetration, canopy volume, yield, and the nutritional profile of hazelnuts during their sixth growing season. Three planting densities were tested: 625, 1250, and 2500 trees per hectare (low, medium, and high density, respectively). The results show that medium-density planting provided the best balance between light availability, canopy development, and yield efficiency. The synthesis of monounsaturated fatty acids (MUFA) and α-tocopherol (vitamin E) was more prominent in the medium-density system (80.2% and 10.3%, respectively), suggesting a favorable metabolic response to moderate competition for resources. In contrast, high-density planting yielded the most per hectare (2898 kg/ha) but exhibited lower individual tree productivity (1.16 kg). Low-density planting had the highest light penetration (53%) but lower overall yield (822 kg/ha) and quality, with greater starch accumulation in the fruit. In general, medium-density planting optimized both yield and kernel quality, with potential implications for orchard management and breeding strategies to enhance hazelnut production and nutritional value.

The adaptability of several Italian olive cultivars to high-density cultivation was evaluated from 2020 to 2024 in central Italy by assessing their agronomic behavior, with the aim of identifying which Italian olive cultivars can combine high productivity and suitability for intensive mechanization—through high- and very high-density planting systems—allowing biodiversity valorization. The cultivars were Borgiona, Don Carlo, FS17, Gentile di Anghiari, Gentile di Montone, Giulia, Leccio del Corno, Maurino, Moraiolo, Pendolino, Piantone di Falerone, and Piantone di Mogliano. The international cultivar Arbequina was used as a reference. The olive orchard was planted in 2015, at a tree spacing of 5 m × 2 m (1000 trees/ha). Arbequina was found to have limited vigor and high production efficiency, as reported in other works, therefore confirming its suitability for high-density and super-high-density cultivation. Some cultivars, such as Leccio del Corno, Maurino, FS17, Piantone di Mogliano, and Piantone di Falerone, had a production and yield efficiency that was not different from or even higher than Arbequina. Other cultivars found to be promising were Don Carlo and Gentile di Anghiari, which had a slightly lower productive performance than Arbequina. Overall, the results are encouraging and suggest that some of these cultivars may be suitable candidates for high- and super-high-density olive orchards. This suitability is further supported by their favorable fruit characteristics, which appear to facilitate efficient mechanical harvesting. However, additional data is necessary to enable a more comprehensive assessment of these cultivars, particularly their capacity to maintain canopy dimensions compatible with straddle harvester operation, while maintaining a stable vegetative–reproductive balance over time.

Pollination is a determining factor in achieving economic yield in hazelnut cultivation, and together with variable climate conditions, this requires the use of artificial pollination. This study evaluated the efficiency of artificial pollination performed with a manual sprayer using pollen from three pollinizer cultivars on the ‘Tonda Francescana^®’ commercial orchard and the effect of different pollen sources on nuts. Dry pollens were applied by a Pollen Blower machine twice during female blooming. The pollen of ‘Nocchione’ determined the highest fruit set and yield per tree, even if it did not determine the highest blank seed percentage. The open pollinizers exhibited a lower sphericity and shape index (NSI), ‘Camponica’ pollen was associated with the biggest nut and kernel; ‘San Giovanni’ pollen showed higher nut elongation. Artificial pollination turned out to be a good tool to increase yield, but its efficiency is strongly influenced by the pollen used.

In Brazil due to the establishment of new orchards, olive seedling production is growing strongly, while the use of biostimulants in agriculture has been gaining attention due to their benefits in root formation and nutrient absorption. This study evaluated the use of biostimulants for promoting the growth of 3-month-old rooted olive seedlings in pots and to assess the nursery quality of the seedlings. Rooted cuttings of Arbequina, Maria da Fé, and Ascolano 315 cultivars were treated with Azospirillum brasilense (Az) and humic substances (HS), alone and in combination. Growth parameters, such as height and stem diameter, were measured every month and after 150 days, seedlings per treatment were also analysed for aerial and root fresh and dry biomasses. Arbequina exhibited the highest growth rate with Az and best absolute growth rate with Az + HS treatment. The total dry matter of the olive seedlings, comprising both the aerial and root part, was influenced by both Azospirillum brasilense and humic substances, enhancing nitrogen availability. The three treatments showed their positive effects on aboveground growth and overall plant vigour. Despite increased biomass, treated olive seedlings showed no significant height advantage over controls, suggesting that the effects may appear in later developmental stages.

Feijoa (Acca sellowiana Berg) is an emerging Mediterranean crop valued for its nutraceutical potential but still underexplored with respect to cultivar and harvest stage. This study investigated two cultivars, ‘Mammoth’ and ‘Apollo’, harvested one week apart (4 and 11 November), to assess morphological traits, phenolic composition, antioxidant activity, vitamin C, and iodine. Fruit morphology, firmness, and basic quality indices (TSS, TA, pH, TSS/TA) were determined, while phenolic compounds were profiled by UHPLC–Q-Orbitrap HRMS. Antioxidant activity was measured by ABTS, DPPH, and FRAP assays; vitamin C by DCPIP titration; and iodine by iodometric analysis. ‘Apollo’ produced larger and firmer fruits, especially at the first harvest (105.6 g), while ‘Mammoth’ showed smaller and softer fruits. TSS remained stable (11 °Brix), whereas TA decreased and pH increased over time, raising the TSS/TA ratio and suggesting improved flavor balance at later harvests. Peel consistently contained higher bioactive levels than pulp, with catechin as the dominant phenolic compounds (up to 345 µg g⁻¹ dw in ‘Apollo’ peel). Antioxidant activity was markedly higher in peel, with ‘Mammoth’ showing stronger early FRAP values and ‘Apollo’ increasing at the later harvest. Vitamin C and iodine were about threefold higher in peel than pulp and increased over time, reaching maxima in late-harvest peel samples. Overall, cultivar and harvest stage significantly influenced fruit quality and nutraceutical value. Peel, particularly that of late-harvested ‘Apollo’, represents a promising resource for functional foods and the valorization of processing by-products.