DELAYING FLOWER OPENING OF CUT ROSES BY CIS-PROPENYLPHOSPHONIC ACID

The effect of a pulse treatment with cis-propenylphosphonic acid (PPOH ) on the opening of cut rose flowers (Rosa hybrida L.) was investigate d. Treatments with a 5 or 10 mM PPOH solution for 20 hr delayed openin g of cut 'Sonia' roses kept in vase water at 20-degrees-C. PPOH had no effect on the change of the flower weight. In this experiment, the cu mulative water uptake of PPOH-treated flowers during the first 4 days decreased accompanied by a simultaneous decrease in total transpiratio n. Analysis of the similar experimental results obtained from June 198 9 to July 1990 revealed a significant, positive correlation between th e delaying effect of PPOH on the flower opening and PPOH uptake into t he flowers (P < 0.01). In field experiments in which PPOH-treatment wa s carried out in a commercial planting grower, 5 or 10 mM PPOH treatme nt for 30 hr also delayed the flower opening of cut 'Carlred' roses. T he delaying effect of PPOH was more evident when flowers were kept in vase water at 10-degrees-C than were kept at 20-degrees-C. The treatme nt was effective even with a 6-hr treatment, When the PPOH-treated flo wers were held at 10-degrees-C for 2 days longer than the water-treate d ones, the former were comparable to or superior with the latter in t heir opening rates and appearance when both lots were transferred to 2 0-degrees-C. Similar PPOH results were obtained with 'Bridal Pink', 'A alsmeer Gold' and 'Marina'. The results indicate that PPOH pulse treat ments: 1) can delay the opening of cut rose flowers, particularly when held at 10-degrees-C, and 2) may extend the shelf life of the flowers if refrigerated in the stockroom at a retail shop.