Differences in Cooling Curve and Postharvest Physiology of Vacuum-Cooled Individual and Bunch Cut Rose (Rosa hybrida L.) Flowers

摘要

Individual and bunches of cut rose (Rosa hybrida L.) flowers were pretreated with vacuum cooling under a pressure reduction rate of 176.24 mbar min and for a fixed cooling period of 338 s. Following cooling, the cut flowers were subjected to cold storage (1deg C, 3 d) and then placed in water to determine their vase life. The real-time surface temperatures of the inner petal, outer petal, leaf and stem were measured using a thermal infrared camera. Vase life, flower opening index, fresh weight, stomatal conductivity and transpiration rate were determined. The results showed that the sequence of the decrease in the cooling rates of the four parts of bunches of flowers was from the leaf, stem and outer petal to the inner petal. This was very different from the sequence in individual flowers, which was from the outer petal, leaf and stem to the inner petal. The vase life of individual flowers was 1.6 d longer than that of bunches of flowers. Results obtained on fresh weight, opening index, stomatal conductivity and transpiration rate indicated that individual flowers retained quality at a higher level than bunches of flowers. These findings suggest significant differences in temperature variations and physiological reactions between individual and bunches of flowers treated with vacuum cooling.