Preharvest Foliar Application of Si–Ca-Based Biostimulant Affects Postharvest Quality and Shelf-Life of Clementine Mandarin (Citrus clementina Hort. Ex Tan)

Abstract

Citriculture and the postharvest industry are in the quest for biostimulants that favour fruit quality and extend shelf-life. Recently, Si has emerged as a biostimulant and its impact on fruit quality and postharvest shelf-life needs to be elucidated. The experiment is conducted for two consecutive years (2019 and 2020) in a commercial citrus orchard. In the present study, a Si–Ca-based product (Gravital® Force SC, AGROLOGY SA, Sindos, Greece) is foliar sprayed upon clementine mandarin (Citrus clementina Hort. Ex Tan cv. SRA 63) trees from August to November, while unsprayed trees are kept as controls. At commercial maturity, both sprayed and unsprayed fruits are harvested and stored for thirty (30) days at 5 °C with 90–95% relative humidity. Afterwards, they are kept at shelf temperature (20 °C) for six (6) days (shelf-life). At different intervals [at harvest, after cold storage (30 d at 5 °C), at the third day of shelf-life (30 d at 5 °C plus 3 d at 20 °C) and sixth day of shelf-life (30 d at 5 °C plus 6 d at 20 °C)], fruits are sampled and analysed for their qualitative characteristics. According to the results, the preharvest foliar application of the Si–Ca-based product delayed fruit maturation, increased peel firmness, total soluble content, total acidity, ascorbic acid, total phenols and antioxidant capacity, and reduced fruit decay during shelf storage. Results suggest that the preharvest foliar spray of Si–Ca products is able to maintain the postharvest quality of mid-ripening mandarin fruit.