Application of cytokinin under modified atmosphere (MA) de-lays yellowing and prolongs the vase life of Davallia solida (G. Forst.) Sw. leaves

Cut leaves of  Davallia solida are widely used in bouquet greenery, however it wilts and yellows after 7 days. Postharvest applications of exogenous cytokinins (CKs), a plant growth regulator (PGR), preventing senescence in many green leafy plants, were studied by pulsing cut D. solida leaves with 6 benzylamiopurine (BA) at a concentration of 100 ppm , or thidiazuron (TDZ) at a concentration of 10 mM for 24 h, compared to distilled water as a control, and then placing the ferns in a controlled room (21+2 °C, 70-80% relative humidity (RH), under cool-white fluorescent lights for 12 h/d). Pulsing BA and TDZ delayed leaf yellowing and maintained Chlorophyll (Chl) content. This was due to reduced Chl degrading enzyme activities on day 8 of vase life of leaves, resulting in longer display life to 11.1 and 11.5 days, respectively. TDZ delayed Chl breakdown on day 8 of vase life of leaves more than BA. Subsequently, leaves were pulsed in 10 mM TDZ, or distilled water for 24 h, and then 10 leaves from each treatment were packaged in a 25x30 cm, 25-mm thickness BOPP bag. All packages were stored at 10 °C in 10 h/d light for 1, 2 and 3 weeks, then unpacked and placed in distilled water. Pulsing with TDZ before 1-week storage delayed leaf yellowing, maintained Chl content, and extended their vase life to 9.6 days compared to 1-, 2-, and 3-week control leaves with vase life of 3.6, 5.8, and 6.2 days. After 1 week, relative fresh weight of leaves and water uptake did not alter between control and TDZ. The activities of Chl degradation enzymes in leaves of D. solida pulsed with TDZ prior to storage were significantly suppressed, related to higher Chl content and a lower percentage of leaf yellowing than the control, resulting in a longer their vase life to 9.0 days, while the control had 7.0 days. A 10 µM TDZ pulsing treatment significantly prevented the yellowing of D. solida fronds during the vase period or storage period and 1-week storage under MA with light condition was recommended for retaining the postharvest quality after storage.