Variability between silver thiosulfate and 1-naphthaleneacetic acid applications in prolonging bract longevity of potted bougainvillea

Potted bougainvillea `Purple Flower' and `Taipei Red' in four different stages of bract development were sprayed with STS (0.1, 0.5 mM) or NAA (25, 50 ppm) and were moved to lowlight indoor conditions after treatment. The experiment was conducted twice, and the results showed that 0.5 mM STS and NAA (25, 50 ppm) could signi®cantly prolong the longevity of bracts at certain stages in both cultivars. Treatment with 0.1 mM STS, however, had no effect on bract longevity of `Taipei Red' at any stage. The prolonging effect of STS was more obvious in early bract stages and decreased as the bract stage increased, whereas NAA applications at later bract stages produced better results on prolonging bract longevity. The ethylene production rates of bracts in these two cultivars were higher in early stages and gradually decreased with bract growth. We propose that this phenomenon is related to the variability between STS and NAA in prolonging bract longevity of bougainvillea. # 2001 Elsevier Science B.V. All rights reserved.