An issue of common concern in lemon production is finding a safe and efficient alternative to 2,4-dichlorophenoxyacetic acid (2,4-D). In this study, ‘Eureka’ lemon fruits were treated with three concentrations (1, 2 and 3) of fluroxypyr-meptyl (FME), a combination of fluroxypyr-meptyl and fluroxypyr (FLFM), 2,4-dichlorophenoxypropionic acid (2,4-DP), and 2-methyl-4-chlorophenoxyacetic acid (MCPA). Water and 2,4-D served as controls. We measured the storage performance indicators of fruit, such as weight loss rate and decay rate, and shelf-life quality parameters, such as juice yield, flavor compounds and pesticide residues. During storage, weight loss was significantly higher in water than under all other treatments. Weight loss rates under FME2 and 2,4-DP3 were significantly lower than under 2,4-D. Decay rates in FLFM1, 2,4-DP2, and the FME series were significantly lower than in 2,4-D and water, whereas those in 2,4-DP1 and the MCPA series were significantly higher than in 2,4-D at 200 days after treatment. Regarding shelf-life performance, juice yield in water (65.14%) and 2,4-D (68.26%) was significantly lower than under most other treatments. The highest juice yield was observed in FME2 (77.84%). Treatments 2,4-DP1, 2,4-DP2, and FME2 were superior to 2,4-D and water in maintaining total soluble solids, titratable acid, and vitamin C contents, while other treatments showed no negative effects on internal quality. Fruits under MCPA2, 2,4-DP3, 2,4-DP2, and FME2 maintained better flavor compound profiles than those in water. Notably, MCPA2 resulted in significantly higher levels of terpenes (e.g., D-limonene) and aldehydes (e.g., citral); FME2 effectively maintained linalool, geraniol, and α-terpineol; and 2,4-DP3 performed well in maintaining D-limonene, sesquiterpenes, and alcohols compared with other treatments. All treated fruits complied with Chinese National Food Safety Standard Maximum Residue Limits for Pesticides in Food GB 2763-2026 and meet the EU standard limits for citrus. Overall, FME2 treatment resulted in the best storage performance and quality, followed by 2,4-DP3, indicating that these treatments may serve as effective postharvest alternatives for lemon preservation.
Ren et al. (Tue,) studied this question.