Postharvest handling and vase life of cut sunflower

The 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' sunflowers were either recut before or after a drying period up to 48 h. Water uptake, stem quality, and microbial counts were determined 4 days after rehydration. Water potential was determined on five corresponding leaves per treatment. The effects of stem number per vase were evaluated with either 1, 3, 5, or 10 stems. Efects of cooling rate were determined by temperatures of 5 [degrees]C for 3 days in the dark, 5 [degrees]C for 2 days in the dark preceded by 24 h at either 20 [degrees]C with light or 32 [degrees]C in a shaded area outdoors, or were maintained in a shaded area at 32 [degrees]C for 3 days. Hydration and storage temperature effects were determined by either transferring to a postharvest environment, 20 [degrees]C cooler for 2 h, immediate storage for 2 days at 5 [degrees]C, or 3 days at 5 [degrees]C after recutting the basal stem. Allowing stems to dry up to 48 h reduced vase life by 2.3 days or less. Vase life was unaffected by harvesting into water or by the 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 [+ or -] 0.5 [degrees]C followed by postharvest evaluation at 20 [+ or -] 1 [degrees]C.