Bordeaux mixture accelerates ripening, delays senescence, and promotes metabolite accumulation in jujube fruit

Abstract

Abstract The old, but eco-friendly pesticide, Bordeaux mixture (Bm), is widely used in agriculture. Here, the effects of Bm on preharvest fruit ripening, and postharvest senescence of fruit and the accumulation of antioxidants were studied in Ziziphus jujuba. A 200× dilution of Bm enhanced preharvest ripening and retarded jujube fruit postharvest senescence. Treatment with Bm increased the reddening index and promoted the accumulation of total phenolics (TP) and the total antioxidant capacity (TAC) in preharvest fruit. However, this Bm-accelerated ripening could be partly reversed using dimethylthiourea (DMTU), a specific scavenger of reactive oxygen species. Compared with preharvest fruit, Bm treatment decreased weight loss and decay and increased firmness in postharvest fruit. Similarly, Bm-delayed senescence was partly reversed using dimethylthiourea. Moreover, the decrease in TP and TAC during storage was partly impeded by Bm. A higher H2O2 content was detected in preharvest fruit than in postharvest fruit. Moreover, this Bm-induced H2O2 accumulation was significantly mitigated using dimethylthiourea. Interestingly, both preharvest and postharvest spraying with Bm significantly enhance copper and calcium accumulation in fruit. Thus, Bm can be widely used before or after harvest to improve fruit quality.