Alleviation of effects of exogenous ethylene on cut 'Master' carnation flowers with nano-silver and silver thiosulfate

Postharvest treatment with nano-silver (NS) extends the longevity of many cut flowers, including carnation (Dianthus caryophyllus L.). Its beneficial effects are generally attributed to the inhibition of bacterial growth in basal stem-ends. However, Ag+.. ions released from NS are also potential blockers of ethylene action. In the present study, we investigated the efficacy of NS pulse treatment, compared with conventional silver thiosulfate (STS) treatment, for alleviation the effects of exogenous ethylene on cut standard 'Master' carnation flowers. Cut carnations exposed to 5 or 10 mu L L-1 ethylene for 12 h showed reduced vase life, inhibited flower opening, premature wilting, and petal discoloration, which markedly diminished their ornamental quality. A NS pulse treatment of 250 mg L-1 (2.3 mmol L-1) for 1 h prior to ethylene exposure reduced the inhibited flower opening and, thereby, prolonged the vase life. These effects were comparatively inferior in terms of flower opening and vase life extension to those obtained with a 1.0 mmol L-1 STS pulse for 1 h. However, without exogenous ethylene NS treatment was nearly as effective as STS treatment for enhancing flower opening and extending vase life. NS treated cut carnation stems (exposed to exogenous ethylene or not) also maintained higher relative fresh weight during the vase period than those treated with STS. The Ag concentration in the stem-ends of the NS-treated cut carnations was higher than that in those of STS-treated stems, and was also higher than that in other tissues. Moreover, Ag provided by NS also reached the receptacles, calyxes, and petals. Overall, NS pulse treatments enhanced the ornamental quality and extending the vase life of cut 'Master' carnation flowers by antagonizing the deleterious effects of ethylene and probably inhibiting the proliferation of bacteria at the cut stem-ends.