Physiological and biochemical modifications by postharvest treatment with sodium nitroprusside extend vase life of cut flowers of two gerbera cultivars

Senescence is a major problem of gerbera (Gerbera jamesonii) cut flowers limiting their long-distance transportation and subsequent marketing. This study was designed to evaluate whether external application of nitric oxide (NO), provided through 150 mu M sodium nitroprusside (SNP), could extend the vase life of gerbera cut flowers, as well as the potential physiological and biochemical mechanisms involved. We used two gerbera cultivars 'Bayadere' and 'Sunway'; watered 'Bayadere' cut flowers have a better performance than watered 'Sunway' cut flowers. NO extended the vase life of cut flowers of both cultivars as compared with their respective control treated with water alone, with 'Sunway' showing better postharvest performance than 'Bayadere'. Application of SNP in vase solution resulted in a decrease in proline content in the stems of cut flowers of both cultivars, providing evidence for alleviation of water deficit in SNP-supplied cut flowers. Improved postharvest performance of SNP-treated gerbera cultivars could be attributed to increases in total phenol and flavonoid contents, which resulted from decreased polyphenol oxidase activity and increased phenylalanine ammonialyase activity. A decline in malondialdehyde accumulation in the stems of SNP-treated cut flowers was greater in 'Sunway' flowers than in 'Bayadere' flowers, which was ascribed to the better performance of antioxidant systems in SNP-treated 'Sunway' flowers to reduce the adverse effect of oxidative stress. Taken together, exogenous NO might be promising approaches to improve postharvest performance of flowers.