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- Indicadores precoces de longevidade em buganvília envasadaPublication . Gago, Custódia; Monteiro, José A.The aims of this work were to study bract and flower abscission in Bougainvillea spectabilis ?Killie Campbell? plants, under post-production conditions. The effect of spraying with Silver Thiosulphate (STS) and with Naphtalene Acetic Acid (NAA, at high concentration: 500 mg.l-1), separately or together, was tested on plants exposed or not to exogenous ethylene. Quantification of non-structural carbohydrates in the bracts, leaves and stems, as well as the respiratory rates of these plant organs were assessed. In another stage, the photosynthetic rates of leaves and bracts were determined and the anthesis of the flowers, existing in the interior of each group of bracts, was monitored. In the absence of exogenous ethylene, NAA was enough to reduce CD bract abscission during post-production. If plants were exposed to exogenous ethylene, then the treatment STS+NAA was needed to reduce bract abscission. Pooling together the four post-production treatments, bract abscission was positively correlated with bract+flower dark respiration, and with bract+flower total non-structural carbohydrates. Similary to what was previous found for other plant organs bract+flower respiration seems to be a good early indicator of bract longevity. Plants that presented greater bract longevity (i. e., NAA and STS+NAA treatments) were the ones that had a reduced percentage of opening flowers and whose flowers had shorter period of anthesis. Flower and bract longevity in potted bougainvillea are distinct events although they abscise together.
- 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.