Determinación de la concentración de aceites esenciales en frutos de limón ubicados en la zona interior y exterior de árboles podados y sin podar

Uruguayan citrus cultivation covers approximately 13.300 hectares and has an annual production of around 245.000 tons, of which 40% is exported. However, lemons, which account for 31% of production, are mainly used for the extraction of essential oils (69%). The concentration and composition of these compounds, located in the flavedo glands, depend on the microclimate of the tree, the ripeness of the fruit, and management practices. There is little information on the effect of pruning and the location of the fruit on the tree on the production of essential oils. The overall objective of the study was to evaluate the concentration of essential oils in lemon fruits located in the inner and outer areas of pruned and unpruned trees. The specific objectives were: determine the effect of pruning and fruit location on fruit color, peel thickness, and essential oil concentration as maturity progresses. The study was conducted in a commercial orchard of “Criollo” lemons (Citrus limon (L.) Burm. F.) located in Kiyú, San José. Sixteen trees were used, divided into two treatment groups (pruned and unpruned), and fruits from inside and outside the canopy were evaluated on three harvest dates (June, July, and August 2021). Photosynthetically active radiation (PAR), temperature, and relative humidity were recorded during Stage II and III of fruit growth, and at harvest, size, color, and essential oil content were determined using the Scott method. Statistical analysis was performed using linear models with repeated measures over time and Tukey's test (p ≤ 0.05). Pruning increased PAR radiation transmission into the canopy at the beginning of the season, but the differences decreased toward autumn due to vegetative growth. In both pruned and unpruned trees, the fruits in the interior remained greener than those on the outside and had a higher concentration of essential oils, regardless of treatment. Advancing ripeness reduced the concentration of oils, with the lowest values obtained in August. Pruning also significantly reduced the oil content. The main conclusions of the study are: (1) Criollo lemons harvested in the middle of the season (June and July) had a higher concentration of essential oils than those harvested at the end of winter (August), (2) pruning at the end of November caused a reduction in the concentration of essential oils in the fruit, and (3) fruit located in the interior of pruned and unpruned trees achieved less coloration than those on the outside and had a higher concentration of essential oils. These results highlight the importance of microclimate and management as determinants of essential oil yield in lemons and demonstrate the need to further develop management practices aimed at optimizing this high-value component.