Growth regulator mediated mitigation of moisture stress in Gladiolus grandiflorus L.

Abstract

Drought stress is a key constraint that hampers growth, flowering, and postharvest quality in gladiolus. This study examined the effect of growth regulators in mitigating moisture stress in two gladiolus (Gladiolus grandiflorus L.) cultivars, Arka Amar and Arka Darshan, under a rain shelter during 2024–2025. The study was set up in a factorial Completely Randomised Design consisting of two moisture regimes. (100 and 75% field capacity) and three growth regulator treatments comprising melatonin (100 µM), brassinolide (0.3 mM), and an untreated control.Moisture stress at 75% field capacity significantly reduced spike length, rachis length, number of florets per spike, vase life, and photosynthetic rate. Arka Amar consistently outperformed Arka Darshan under both moisture regimes. Among the treatments, melatonin was most effective in improving floral, physiological, and biochemical traits, followed by brassinolide. The best performance was recorded in Arka Amar under 100% field capacity with melatonin, which showed maximum spike length (97.05 cm), vase life (10.50 days), and enhanced photosynthetic and antioxidant responses.The results indicate that melatonin can effectively mitigate moisture stress in gladiolus by improving floral quality, photosynthetic efficiency, and biochemical responses, with Arka Amar exhibiting greater tolerance than Arka Darshan.