The extensive use of chemical fertilizers is responsible for numerous environmental problems including low food quality, soil degradation, and toxicity to beneficial living organisms in the soil. Nano-fertilizers (NFs) application may be a promising solution for combat these challenges. The current study focused on the efficiency of applying small amounts of NFs incorporated with conventional nitrogen, phosphorus, and potassium (NPK) fertilizers to reduce the quantities of conventional fertilizers (CFs) in lettuce cultivated in sandy soil. This study evaluated the effect of these incorporations on plant growth, yield, phytochemical accumulation, leaf nutrient, and leaf nitrate. A pot experiment was conducted during the winter seasons of 2020/2021 and 2021/2022 using the following treatments: CF100: 100% CFs, CF75NF25: 75% CFs + 25% NFs, CF50NF50: 50% CFs + 50% NFs, CF25NF75: 25% CFs + 75% NFs, and NF100: 100% NFs (=10% of CFs). Our findings displayed that the CF75NF25 and CF50NF50 treatments recorded the highest plant growth parameter values (plant length, root length, number of leaves, and fresh and dry biomass). The maximum of chlorophyll fluorescence measurements (photosystem II efficiency) were obtained in plants fertilized with CF75NF25, followed by CF50NF50 and CF100. The improvement ratios of photosynthetic pigments (Chlorophyll (Chl) a, b, and total) for CF75NF25 were 23.77, 50, and 23.72% in the first season and 10.10, 51.0, and 24.90% in the second season for Chl a, b, and total, respectively, as compared with the CF100 treatment. A similar tendency was observed for the CF50NF50 treatment. Generally, CF75NF25 significantly raised the content of total phenolic compounds (TPC), total flavonoid content (TFC), and antioxidant activity (AOA) in lettuce plants by 36.09, 47.82, and 40.16% in the first season and by 30.39, 37.53, and 32.43% in the second season, respectively, compared with CF100. In addition, the levels of leaf nutrient content and uptake of N, P, and K were significantly higher in plants fertilized with CF75NF25 compared to the other treatments, whereas CF25NF75 had the lowest values among the different treatments across both seasons for most of the tested traits. The nitrate content in lettuce leaves (NO₃⁻) for both seasons was lower than the acceptable level for human consumption. These results indicate that incorporating a low concentration of NFs into CFs could be a promising strategy to reduce the amount of CFs to 75% or 50% of lettuce NPK requirements without significant adverse effects on the growth and productivity of lettuce plants cultivated in sandy soil.

The short shelf-life and loss of bioactive compounds of strawberry fruit are the most important problems during strawberry refrigerated storage. This study was carried out to evaluate the effect of the pre-harvest foliar application of salicylic acid (SA) (2 and 4 mM), abscisic acid (ABA) (0.25 and 0.50 mM), and methyl jasmonate (MeJA) (0.25 and 0.50 mM) three times, 10 d apart, at fruit development and ripening stages on storage ability and bioactive compounds of strawberry fruit (cv. Festival) stored at 4 °C for 12 d. Our results showed that fruit obtained from both concentrations of ABA and 0.25 mM MeJA was firmer and had higher total soluble solids (TSS) than fruit from non-treated plants. However, all previous applications had no significant effect on weight loss, pH, or color. Applications of 4 mM SA and 0.25 mM MeJA conserved fruit from ascorbic acid (AsA) loss compared to control at the end of the storage period. In addition, all pre-harvest applications remained higher in total phenolic compounds (TPC) and anthocyanin contents compared to controls at the last storage period. Hence, the pre-harvest application of SA, ABA, and MeJA could be used to conserve TPC and anthocyanin as well as the quality of strawberry fruits during refrigerated storage.

The present study evaluated the impact of edible coatings based on whey protein concentrate (WPC) and mango peel extract (MPE) on the shelf life, physicochemical, and microbial properties of minimally processed broccoli preserved at 5 ± 1 °C for 28 days. The variations in the physicochemical and microbial properties of the broccoli fresh-cuts were evaluated by determining the following parameter changes: weight loss, color, respiration rate, ascorbic acid content (AsA), sulforaphane content (SF), total phenolic content (TPC), antioxidant activity (AOA), total bacteria, fungi counts, and sensory evaluation. Broccoli fresh-cuts were treated with WPC alone or in combination with MPE (WPC/MPE) at 1% or 3%, and uncoated broccoli fresh-cuts were a control. The obtained results revealed that all the coated broccoli fresh-cuts showed lower weight loss than the uncoated broccoli fresh-cuts. The coating with WPC/MPE at 3% recorded the lowest weight loss among all treatments; however, it wasn’t significantly lower compared to WPC/MPE at 1%. The addition of MPE to WPC in coating solution at 1% and 3% resulted in a higher value of the (-a*), indicating better green color retention and decreased floret yellowing. All applied coatings significantly conserved the bioactive compounds (AsA, SF, and TPC) and AOA of broccoli fresh-cuts compared to uncoated ones. At the end of the storage period, the maximum values of the aforementioned bioactive compounds were recorded in the broccoli fresh-cuts coated with WPC/MPE at 3% followed by WPC/MPE at 1%, and WPC alone compared to uncoated broccoli fresh-cuts. The broccoli fresh-cuts coated with WPC/MPE at 3% recorded a higher score on sensory evaluation than those coated with WPC/MPE at 1%, followed by broccoli fresh-cuts coated with WPC alone. The WPC-based edible coating combined with MPE (WPC/MPE) at 3% showed the highest reduction in the total fungi and bacterial counts compared to all the other treatments.