Effect of two reflective materials on the physiological and production behaviour of bergamot (Citrus bergamia Risso et Poiteau) plants

The Mediterranean basin area is characterised by photosynthetic photon flux density, which is often well above the saturation level point of the leaf. This phenomenon has been exacerbated by global warming, giving rise to reactive oxygen species in chloroplasts, which can damage tissues (photodamage) and reduce photosynthetic potential.

Citrus bergamia Risso et Poiteau (bergamot) was successfully cultivated in Southern Italy for the high-quality essential oil extracted from the flavedo fruit and freshly consumed for its numerous health properties.

This study aimed to use two reflective materials, caolin and calcium carbonate, to improve tree productivity. The experiment was conducted over two years in southern Italy. A randomised block design was used in this study. At harvest, fruit samples were randomly detached.

The results showed that bergamot trees treated with reflective materials significantly increased the average yield per plant compared to that of the control plants, but the effect was stronger with caolin and calcium carbonate. The number of fruits at harvest was similar between the treatment and control trees; therefore, there was no effect of the two reflective materials on decreased fruit pre-harvest, but the change in yield was attributable to an increase in fruit size. This can be attributed to the higher performance of the leaves covered by reflective materials. Regarding maturation, the indices were not influenced by the treatment, whereas ascorbic acid was higher in the fruit of the treated trees. Essential oil production was improved by this treatment. This improves both the essential oil yield, used as a base for the worldwide perfume industry, and the nutraceutical parameters for fresh consumption, justifying the increased costs of applying reflective material on the tree.