Preharvest Foliar Spraying Combined with Postharvest Salicylic Acid Treatment Regulates Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) Fruit Quality and Softening during Storage

Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) have a short shelf-life, which hampers their marketability. To investigate effects of combined pre- and postharvest treatments on quality and softening during storage, preharvest Guomantian foliar fertilizer (FF) spray and postharvest salicylic acid (SA) dip were applied to panzao. By day 63 of storage, fruit firmness responded to treatment in the order of FF+SA treatment > FF or SA treatments > Control. All treatments inhibited fruit reddening during storage and, compared with those of the control, alleviated the decline in total soluble solids, ascorbic acid, and phenol contents and decreased the oxidative aging process, which was consistent with the change in firmness. The FF+SA treatment reduced the activities of amylase, cellulase, polygalacturonase, and β-glucosidase, which decreased the degradation of macromolecules including starch, cellulose, and pectin. Principal component analysis showed that FF+SA exhibited a synergistic effect and was the most effective treatment for maintaining fruit quality during storage. FF increased accumulation of nutrients during growth and improved quality, while SA delayed the decline in fruit quality and reduced softening. These results provide the theoretical basis and technical knowledge for improving the shelf-life of panzao during storage and long-distance transportation.