Effect of the Substrate Water Content on the Postharvest Quality and Shelf Life of Potted Kalanchoe blossfeldiana

In this study, we investigated the effects of the substrate water content on potted kalanchoe (Kalanchoe blossfeldiana) in an export distribution simulation. Potted kalanchoe plants were treated either with the optimum substrate water content (OSW, 50– 60%) or a low substrate water content (LSW, ≤ 20%) and the postharvest quality and shelf life were assessed at farm or wholesale, export, auction, and consumer stages. The shelf life of the LSW flowers was shorter than that of the OSW flowers by 36%. The primary reason for the short shelf life after the LSW treatment was an increase in leaf chlorosis. The plant height was shorter with the LSW treatment at all stages, while the plant width was longer before the export stage. The fresh and dry weights of the root with the LSW treatment were lower at all stages. The chlorophyll content and the Fv/Fm of the leaves were lower during the auction stage for the LSW treatment. The Fv/Fm of the OSW treatment and LSW treatment were 0.79 and 0.77, respectively, during the auction stage. The change in the size of the stomatal pores and complexes was higher for the LSW treatment at all stages, but this difference was not significant. The difference between the air temperature and the petal or leaf surface temperature did not differ between treatments at the auction stage and consumer stage. The correlation between the shelf life and plant height was positive for all stages. There was no correlation between shelf life and the temperature of the flowers or leaves on auction stage and consumer stage. At the end of the shelf life, there was a high positive correlation between the shelf life and the substrate water content (r = 0.8**), the number of flowers (r = 0.8**) or buds (r = 0.6**), and flowering rate compared to the shipment (r = 0.5*) at the consumer stage. The findings here indicates that the substrate water content affects the postharvest quality and shelf life of potted kalanchoe.