Benzyladenine and gibberellins improve postharvest quality of cut Asiatic and Oriental lilies

The effects of the duration of cold storage, as well as the concentration, timing, and means of application of a solution containing 25 mg.L-1 each of benzyladenine (BA) and gibberellins (GA(4+7))on the postharvest quality of cut Asiatic and Oriental lilies (Lilium sp.) were evaluated. Depending on the cultivar, lower leaves began to turn yellow between 1 and 2 weeks after placing non-cold-stored stems in a 20 degreesC room illuminated 12 h.d(-1) with 8 mu mol-m(-2)-s(-1) from cool-white fluorescent lamps. Leaf yellowing continued to progress upward until the end of the vase life. Cold storage (3.3 degreesC) worsened the leaf disorder, particularly, on the Oriental lily 'Stargazer'. The longer the duration of cold storage, the earlier the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. In addition, cold storage induced bud blasting, inhibited flowers from fully opening, and reduced the longevity and fresh weight of open flowers and the vase life of cut stems. Spraying leaves with a solution containing 25 mg.L-1 each of BA and GA(4+7) significantly reduced cold-storage-induced leaf yellowing, bud blasting, and vase life of three of the four cultivars tested. The development of leaf yellowing declined with increasing concentration of BA+GA(4+7). The susceptibility of 'Stargazer' to cold-storage-induced leaf yellowing and bud blasting can be counteracted by a concentration of growth regulators higher than that which was effective for the other cultivars. Timing of the BA+GA(4+7) application was not critical, as there were no differences in leaf yellowing or bud development when the solution was sprayed before or after the cold storage. Addition of BA+GA(4+7) (0.5 or 2.5 mg.L-1 of each) to the preservative solution or a pulsed treatment in solutions containing 25 mg.L-1 each of BA and GA(4+7) for 4 hours prevented leaf yellowing, but increased bud blasting. For practical applications, growth regulators can be sprayed prior to or after cold storage in order to improve the postharvest leaf and flower quality of cut lilies.