Effect of Exogenous Nitric Oxide Application on Physiological and Antioxidant Responses and Scape Bending Reduction in Gerbera Cut Flower

Gerbera ranks among the 10 superior cut flowers worldwide and is valuable from commercial perspective, but its short vase-life due to stem bent neck (stem break) and wilting are the most critical postharvest challenges of this cut flower. Nitric oxide (NO) is a signaling molecule in plants that involves functions in many physiological processes. In this research, the effects of NO on vase-life, physiological and antioxidant responses and stem neck of three gerbera cultivars (red, pink and yellow) were investigated. The structural and histological characteristics of gerbera stem were evaluated, too. The research was a completely as randomized design and a factorial combination flower color (red, pink and yellow) and three concentrations of SNP (0.25, 0.5 and 1 µM) with three replications. Distilled water was used as control. The results indicated that all concentrations of SNP possess antioxidant properties and increased the defense ability of plants. Based on the results, obtained irrespective of flower color, the highest vase-life and the lowest malondialdehyde and hydrogen peroxide were found in 1 µM SNP. The results showed that SNP not only increased vase-life and the activity of antioxidants enzyme and phenylalanine ammonia lyase (PAL), but also significantly decreased the activity of polyphenol oxidase. Moreover, SNP increased the lignin biosynthese of there mechanical tissue which in turn reduced stem neck possibly through the induction of PAL enzyme activity.