Preliminary result on the effect of shading net on 'Femminello Zagara Bianca' lemon (Citrus limon L. Burm. f.) behaviour

Italy is the 11th world producer of lemon (Citrus limon L. Burm. f.) occupying the 14th position in terms of cultivated area, mainly located in the coastal areas of southern regions. In these areas, environmental conditions during summer season are characterized by high temperatures and high solar radiation. The use of shade nets can represent a useful tool to reduce leaf temperature, midday light intensity and soil evaporation during the hottest periods, with a consequent increase in the tree efficiency. Furthermore, the use of the net also protects against atmospheric events (mainly wind and hail) reducing the infection of the endemic Plenodomus tracheiphilus (Petri) Gruyter, a mitosporic fungus responsible for the destructive vascular disease of lemon named 'mal secco'. This preliminary research was conducted during the 2024 growing season in a commercial irrigated orchard, planted on a deep sandy soil located in Sicily. The studied cultivar is 'Femminello Zagara Bianca', and plants were either grafted onto sour orange (C. aurantium L.) and Volkamer lemon (C. volkameriana Ten. et Pasq.). During the research, we analysed the effect on plant physiology, production and fruit quality of a white screening net which reduces approximately 15% of the photosynthetically active incident radiation. The trees under nets were compared with control trees grown under full sunlight. The main parameters describing the photosynthetic efficiency (gas exchange, chlorophyll fluorescence and chlorophyll and polyphenol content in the leaves) were monitored; the production deriving from summer blooms ('verdelli') was evaluated for qualitative and quantitative traits. In both treatments the plants will be also evaluated for the presence of fungal infections. From preliminary observations, the net determined on the plant a positive effect protecting plants from excessive solar radiation, reducing the water requirement and thus increasing the lemons quality.