β-Cyclodextrin-based nanosponges as carriers for 1-MCP in extending the postharvest longevity of carnation cut flowers: an evaluation of different degrees of cross-linking

This study investigated the influence of different degrees of cross-linking of beta-cyclodextrin-based nanosponges (beta-CD-NSs) on the activity of the incorporated 1-methylcyclopropene (1-MCP) to extend the post-harvest longevity of carnation cut flowers. The polymeric beta-CD-NSs were synthesized from cyclodextrins at three varying reticulations, beta-CD-NS 1:2, beta-CD-NS 1:4, and beta-CD-NS 1:8. These carriers were supplied to carry the nonvolatile formulations of 1-MCP at two different concentrations (0.25 and 0.5 mu L L-1, ai) through stem and tissues of cut flowers of Dianthus caryophyllus L. 'Idra di Muraglia', both sprayed and in vase suspension. Treated cut flowers were compared to those receiving like concentrations of commercially prepared gaseous 1-MCP and to neat beta-CD-NS 1:2, beta-CD-NS 1:4, and beta-CD-NS 1:8. Visual checks for symptoms of senescence alteration (VS), petal color variation, and endogenous ethylene production were registered daily. The beta-CD-NS 1:2, beta-CD-NS 1:4, and beta-CD-NS 1:8 complexes favored decorative value maintenance in carnation cut flowers. In particular, the lowest suspended concentration (0.25 mu L L-1) of the beta-CD-NS 1:8 complex proved best for maintaining cut flower ornamental quality. beta-CD-NS 1:8 treated flowers also appeared longer-lived than those treated with both doses of commercial gaseous 1-MCP. Data on petal color variation and endogenous ethylene production were strictly correlated with VS results. The potential for the formulated 1-MCP-loaded beta-CD-NS suspension to induce prolonged vase life was demonstrated. Its use could yield benefits, such as a reduction in total dose and frequency of administration.