Postharvest Storage Conditions and Flower Life of Tulips

To maintain quality, tulips are commonly cold-stored prior to shipment and marketing. It is unknown, however, how this cold storage impacts flower quality. We investigated the effects of postharvest cold storage on carbohydrate status and flower life using two commercially important tulip cultivars, ‘Saigon’ and ‘Strong Gold’. At bud color stage, forced, potted plants were moved from the greenhouse at 17ºC into dark storage at 1ºC, 4ºC, or 7ºC and were held for 1, 2, 4 or 7 weeks. After cold storage, plants were moved into a postharvest evaluation room at 20ºC (12h of light at 8-12 umol/m^-2/sec ^-1) to assess flower life. Cold stored plants were compared to plants moved directly into the evaluation room. In both cultivars, plants stored at 7ºC for 7 weeks had the shortest flower longevity. As duration of storage increased the total soluble carbohydrates (primarily sucrose, glucose and fructose) in buds of ‘Strong Gold’ significantly decreased, but increased in buds and stems of ‘Saigon’. As duration of storage increased to 4 and 7 weeks and temperature to 4ºC and 7ºC, the flower life of ‘Strong Gold’ decreased more rapidly than ‘Saigon’. In both cultivars, starch decreased as temperature and duration of storage increased. Storage up to 1 week caused no significant reductions in flower life in ‘Saigon,’ but any period of storage of ‘Strong Gold’ caused a decrease in flower life. For durations > 1 week, best flower quality resulted from storage at 1ºC in both cultivars, and that storage at 4ºC or 7ºC should be avoided if possible. Future studies will focus on carbohydrate changes occuring upon transfer to a 20ºC environment.