Peach fruit quality is dependent on preharvest treatments and orchard practices. The aim of this study is to evaluate the effects of preharvest potassium silicon fertilization on fruit postharvest quality. Two peach cultivars (“Early Bomba” and “Plagold 17”) were sprayed with three concentrations of potassium silicon (K-Si) at fruit set, stone hardening, and physiological maturity stages. The applied treatments corresponded to control (T0 = 0% K-Si) pulverized with distilled water and two K-Si treatments (T1 = 3% K-Si and T2 = 4.5% K-Si). The blooming and harvesting dates, vegetative growth and agronomical parameters were analyzed over two growing seasons (2021–2022). Peach fruits were stored at 5 °C and 95% RH during two cold storage periods (2 and 4 weeks) followed by 2 days at room temperatures. The fruit weights (FW), color, firmness, soluble solids content (SSC), titratable acidity (TA), pulp stone ratio (P/S) and fruit weight loss (FWL) were evaluated. The anthocyanins, flavonoids, total phenolics, carotenoids and antioxidant capacity (DPPH) were determined. Vitamin B5 and vitamin C were analyzed by HPLC. The ethylene rate and the chilling injury symptoms (CI) were analyzed after two cold storage periods (2 and 4 weeks). Results showed that the applied potassium silicon treatments (3% K-Si and 4.5% K-Si) enhanced the FW, SSC, TA, FWL, fruit composition and CI. Anthocyanins and total phenolics increased after cold storage period under K-Si treatments. The nectarine cultivar (cv) Early Bomba showed low sensibility to chilling injury symptoms as compared to the cv Plagold 17.

The phenotypic diversity of agronomical traits and nut phenolic compound content of four pistachio cultivars (Mateur, Elguetar, Kerman, and Ohadi), conducted under regulated deficit irrigation (RDI) during two growing seasons (2017/2018), were evaluated. The experimental orchard was located in the Regional Center of Agricultural Research of Sidi Bouzid (CRRA), Tunisia. Three water treatments were applied from March to September; control (T0; 100% ETc during all the developmental stages), RDI treatment (T1; 50% ETc during stages I and II of fruit development followed by full irrigation 100% ETc during stage III), and stressed treatment (T2; 50% ETc during all the growing season). The results showed that treatments T0 and T1 no presented statistically significant difference in yield and nut biochemical traits, and 50% less irrigation water was used during stages I and II of nut development. The trees under treatment T2 were affected by water stress showing low values of yield and nut phenolic compounds.