Extending calla lily vase life using silver nitrate, silver nanoparticles, and chlorogenic acid: a novel strategy to sustain xylem conductivity and antioxidant defense

The postharvest longevity of Zantedeschia aethiopica (cut calla lily) flowers is often limited by rapid microbial proliferation and water loss, leading to early wilting and reduced aesthetic quality. This research aimed to evaluate silver nitrate (AgNO₃), silver nanoparticles (AgNPs), and chlorogenic acid (CGA) as preservative agents to maintain physiological and biochemical quality and extend vase life in cut calla lily flowers. Each treatment was applied individually in a completely randomized design (CRD) with three replicates of seven inflorescences each (totaling 21 inflorescences per treatment), using seven vase solutions supplemented with 15 mmol L⁻¹ sucrose: distilled water (control), AgNO₃ at 50 and 100 mg L⁻¹, AgNPs at 15 and 30 mg L⁻¹, and CGA at 15 and 30 mg L⁻¹. Treatments were evaluated at nine predetermined time points, after which their effects were assessed on vase life, water uptake, relative fresh weight (RFW%), relative chlorophyll index (SPAD), total soluble sugars (TSS), protein content, total phenolic content (TPC), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), microbial proliferation at the stem base, and the activities of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). Data were analyzed using one-way ANOVA followed by Duncan's multiple range test (p ≤ 0.05). These findings indicate that AgNPs and CGA significantly extended the shelf life of cut calla lily flowers, with optimal concentrations of 30 mg L⁻¹ CGA and 30 mg L⁻¹ AgNPs. The highest RFW% (101.7 and 101.02%) was obtained from treatment with 30 mg L⁻¹ CGA on day 5 in both seasons. These treatments improved water uptake, reduced water loss, inhibited microbial activity at the stem base, and decreased microbial blockages in the xylem for up to 11 days. Furthermore, treatment with 30 mg L⁻¹ CGA resulted in the highest values of relative chlorophyll index (66.05 and 65.08 SPAD in the first and second seasons, respectively), total protein content (26.09 and 23.08 mg g⁻¹ FW, respectively), and soluble carbohydrates (2.47% and 2.40%, respectively). In addition, this treatment reduced H₂O₂ and MDA accumulation and enhanced antioxidant enzyme activities. Briefly, our results highlight the use of CGA and AgNPs, as well as the potential of incorporating natural antioxidants as a sustainable alternative to conventional preservatives in postharvest floral management.