Melatonin enhances nitric oxide, salicylic acid, and lignin accumulation to reduce neck bending and extend vase life of gerbera cut flowers.

Melatonin (MT) is a versatile signaling molecule involved in plant growth regulation and stress tolerance. This study examined the effects of MT at five concentrations (50, 100, 200, 300, and 400 µM) on neck bending (NB) and vase life of Gerbera jamesonii ‘Pink Elegance’ cut flowers. Morphological, physiological, biochemical, and signaling-related traits were evaluated. The results showed that MT, especially at 300 µM, effectively reduced NB, enhanced water uptake, improved antioxidant defense by increasing activities of SOD, CAT, APX, and GPX, and promoted lignin accumulation in stems. Moreover, MT treatment modulated nitric oxide (NO) and salicylic acid (SA) levels, suggesting a role in stress-related signaling. Overall, MT application improved postharvest quality and extended vase life, highlighting its potential as a practical strategy for maintaining the quality of gerbera cut flowers.