Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Bougainvillea post-production: NAA and STS control of bract abscission is subject to exogenous ethylenePublication . Gago, Custódia; Monteiro, José; Rodrigues, M. H.The effect of NAA (500 mg.L-1 sprayed once at end-of-production), STS (0.4 mM sprayed every 15 days after bracts started to be apparent) and STS+NAA on plants exposed or not to exogenous ethylene (from ethephon), were tested using two completely randomized experiments. At the end-of-production plants were placed for three days under simulated transport conditions (17 +/-1 degreesC, no light) and then, placed under interior conditions (21 +/-1 degreesC and 11 mu mol.m(-2)s(-1) of cool white fluorescent light 12 hr a day). Twice a week, during postproduction (PP) the number of developing (D) bracts as well as the number of completely developed (CD) bracts remaining in the plants were assessed. Among the treatments tested, NAA was enough to reduce CD bract abscission during post-production, abscising at day 32 PP, a maximum of 50% of the bracts, provided that no exogenous ethylene was present. If plants were exposed to exogenous ethylene, then the treatment STS + NAA was needed to reduce bract abscission, abscising at 32 PP a maximum of 58% of CD bracts. At this time, plants treated only with STS had abscised all CD bracts if exposed to ethylene or at least 97% of CD bracts if not exposed to ethylene.
- NAA and STS effects on potted bougainvillea: early flower death allows delayed bract abscissionPublication . Gago, Custódia; Monteiro, JoséThe effects of Silver Thiosulphate (STS) and Naphtalene Acetic Acid (NAA) (0,45%NAA+1,2% NAA-amide at 500 mg.l-1) on flowering bud development, anthesis duration, bract longevity and bract photosynthetic rate were studied in Bougainvillea spectabilis ‘Killie Campbell’ plants, under interior conditions. The relationships between bract longevity and the above parameters were also investigated. NAA induced longer bract longevities, shorter flower anthesis duration and lower percentage of flowers reaching anthesis. STS alone increased duration of flower anthesis but did not affect CD (completely developed) bract abscission, as compared to the water treatment. Depending on the experiment, adding STS to NAA delayed or had no effect on bract abscission. Longer bract longevities were related to shorter flower anthesis and lower percentage of flowers reaching anthesis. Manual removal of flowers from the bract+flower unit increased bract longevity. Despite the low level of irradiance, bracts photosynthesized and plants treated with NAA (alone or with STS) had lower bract photosynthetic rates. Bract photosynthetic activity, although with relevant rates (similar to leaves and most probably capable of covering respiration expenditure) did not seem important as an energy source for bract longevity since bracts that lasted longer had lower photosynthetic rates. In the water control, percentage of flowers reaching anthesis positively correlated with bract photosynthetic rates. In potted bougainvillea under low light conditions, flower senescence and bract abscission are under different types of control. In addition to the classical effect of auxin reducing ethylene production, and/or sensitivity of the abscission zone to ethylene, NAA delays bougainvillea bract abscission via early interruption of flower development.