Pre- and postharvest fulvic acid treatments improve vase life and biochemical attributes of cut Alstroemeria (Alstroemeria aurea) ‘Orange Queen’

Postharvest longevity is a major determinant of cut-flower quality, and natural biostimulants such as fulvic acid (FA) have gained attention as sustainable tools for improving flower quality through their effects on physiological and biochemical responses. This study evaluated the effects of preharvest and postharvest FA applications on vase life, water relations, membrane stability, and antioxidant-related responses of cut Alstroemeria aurea ‘Orange Queen’ flowers. A factorial experiment was conducted under controlled conditions using preharvest soil drenching and postharvest vase-solution supplementation with FA at 0, 50, 100, and 200 mg L −1 . FA application significantly affected several postharvest traits, with 100 mg L −1 producing the most consistent overall responses. This treatment extended vase life from approximately 11–12 days in control flowers to 17–18 days and improved relative fresh weight, relative solution uptake, total phenolic content, antioxidant capacity, and the activities of catalase, ascorbate peroxidase, and guaiacol peroxidase. In addition, FA treatments were associated with lower ion leakage and malondialdehyde accumulation, consistent with improved membrane stability during vase life. The 200 mg L −1 treatment did not consistently provide additional benefits, indicating that the responses to FA were not strictly proportional to concentration and highlighting the importance of optimizing the application rate. Preharvest and postharvest FA application, particularly at 100 mg L −1 , was associated with improved postharvest performance of Alstroemeria cut flowers, together with favorable changes in water relations, membrane stability, and antioxidant-related responses. These findings support the potential use of FA as a component of sustainable postharvest management strategies; however, further studies under commercial conditions and incorporating molecular, hormonal, and other mechanistic approaches are needed to clarify the biological processes underlying FA-mediated responses.