Postharvest Handling and Vase Life of Cut Sunflower

Sunflower (Helianthus annuus L.) is a commercially important cut flower requiring research into postharvest factors such as recutting, water uptake, stem number, cooling rate, and storage temperature to maximize vase life. Stems of ‘Sunbright’ sunflower were either recut before or after a drying period up to 48 hours. Water uptake, stem quality, and microbial counts were determined 4 days after rehydration. Water potential was determined by five corresponding leaves per treatment. Effects of stem number per vase were evaluated with either one, three, five, or ten stems. Effects of cooling rate were determined by temperatures of 5 ºC for 3 days in the dark, 5 ºC for 2 days in the dark preceded by 24 hours at either 20 ºC with light or 32 ºC in a shaded area outdoors or were maintained in a shaded area 32 ºC for 3 days. Hydration and storage temperature effects were determined by either transfer to a postharvest environment, 20 ºC cooler for 2 hours, immediate storage for 2 days at 5 ºC or 3 days at 5 ºC after recutting the basal stem. Allowing stems to dry up to 48 hours reduced vase life by 2.3 days or less. Vase life was unaffected by harvesting into water or number of stems in a vase but was affected by temperature such that the longest vase life of 13.2 days occurred when stems were stored for 3 days at 5 °C + 0.5 ºC followed by postharvest evaluation at 20 °C + 1 ºC.