Efficient Room-Temperature Storage of Toona sinensis with Salicylic Acid Treatment: Enhancing Postharvest Quality Through Antioxidant and Nitrogen Metabolism Modulation

Young leaves and sprouts of Toona sinensis are widely consumed throughout Asia. However, they are highly perishable, resulting in a short shelf life and limited marketability. Low-temperature storage can extend shelf life but is energy-intensive, restricting large-scale use. Salicylic acid (SA) exhibits preservative properties, representing a promising alternative. In this study, we investigated the effects of 250 μmol SA treatment on postharvest T. sinensis buds and leaves stored at 20 °C for 7 days and compared it to low-temperature storage (4 °C). SA treatment delayed wilting, reduced water loss, suppressed total soluble solid accumulation, and inhibited active oxygen free radical and malondialdehyde production compared to the untreated controls at room temperature while outperforming low-temperature storage. The treated buds also maintained higher antioxidant enzyme activity and preserved non-enzymatic antioxidant compounds, including ascorbic acid, polyphenols, and flavonoids. Although total amino acid content steadily increased under SA treatment, individual amino acids greatly fluctuated. SA treatment reduced nitrate reductase and glutamate dehydrogenase activities, as well as NO2•− levels, indicating its effects on nitrogen metabolism. Our findings indicate that SA improves the postharvest quality of T. sinensis buds during room-temperature storage, providing a theoretical basis for applying SA as a storage agent for T. sinensis buds.