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L’importanza ornamentale e scientifica dell’ibisco (Hibiscus rosa-sinensis L.) fiorito in vaso
No full textChanges in abscisic acid and flower pigments during floral senescence of petunia
No full textThe present work was focused on abscisic acid (ABA) changes in three differently coloured petunias during flower development and senescence. The ABA content was studied in correlation with changes of flower pigments and other phytohormones. The variations of anthocyanins and endogenous hormones were induced by treatments with 1 or 2 mM amino-oxyacetic acid (AOA), 50, 100 mu M thidiazuron (TDZ) and 50 mu M 6-benzyladenine (BA). ABA content decreased during bud development and increased during senescence. The AOA reduced the anthocyanins content and avoided ABA increase, while the cytokinins (BA and TDZ) did not significantly affected anthocyanin contents but increased ABA content. TDZ doubled the ABA content compared to the control. However, the treatments did not affected flower life, confirming the secondary role of ABA during flower senescence
Effect of Salt Spray on Six Ornamental Species
No full textMarine aerosol strongly affects the growth and development of urban, garden
and landscape plants. The few studies available are focused on the sodium chloride
effect on plant growth, usually applied in the irrigation water or substrate media. No
information is available on responses of plants to marine aerosol. Therefore, the aim
of this work was to evaluate the physiological responses of some species to sea water
nebulisation treatment. Species were selected among those that are commonly used
along the seaside and among those that might be potentially used. Plants were
bought from local nursery and species used were: Acacia cultriformis, Callistemon
citrinus, Carissa edulis microphylla, Gaura lindheimeri, Jasminum sambac, Westringia
fruticosa. Plants were placed in randomised block in greenhouse and treated once a
day for 5-10 seconds with sea water or irrigation water (control) using a nebulisation
system.
The effect of marine aerosol was studied by monitoring leaf chlorophyll a
fluorescence, chlorophyll content, and leaf area damage by image analysis.
Results were different among species. The effect of treatment was represented
by leaf necrosis, reduction of chlorophyll and chlorophyll a fluorescence. The
resistant species was Westringia fruticosa, while the intolerant species were A.
cultriformis and G. lindheimeri. Intermediate behaviour was observed in the other
species
Application of biostimulants in floating system for improving rocket quality
No full textThe traditional agricultural production systems are evolving more and more towards organic, sustainable or environmental friendly systems. On the other hand, it is important to keep the yield and the quality of crops. The reduction of fertilisers has to be substituted by strategies that improve the nutrients uptake or their utilisation by the plants. The aim of our work was to verify if applications of a biostimulant (Activawe®, Valagro S.p.A.) could reduce the fertilisers use without compromising the production and the quality of rocket (Eruca sativa Mill.) leafy vegetables. The experiments were performed in floating system with standard nutrient solution (NS100%) and Â1⁄4 reduced nutrient solution (NS25%) with or without 0.3 ml L-1 Activawe. The Activawe dose-effect studies were carried out using NS25% without biostimulat (control) or in combination with 0.08, 0.17, 0.3, 0.7, 1.3 or 2.7 mL L-1. Results showed that Activawe increased the nutrient use efficiency in all treatments. In fact, yield and chlorophyll content in NS100% compared with NS25% plus 0.3 mL L-1 Activawe were not statistically different. Moreover, Activawe lowered the leaf nitrate content by 11% in NS100% and by 33% in NS25%. The dose-effect studies showed that increasing Activawe concentration, from 0.08 to 0.3 mL L-1 in the nutrient solution, increased yield and chlorophyll content (values doubled). The effect of Activawe on lowering nitrate content was visible at 0.17 mL L-1, higher concentrations did not give any additional benefit. No phytotoxic effects were observed using Actiwave at all the concentrations tested
Application of Actiwave® for Improving the Rooting of Camellia Cuttings
No full textBiostimulants are generally able to improve mineral use efficiency, enhance plant tolerance to biotic and abiotic stresses and stimulate some physiological processes related to development. In our studies, Actiwave® was tested in floricultural crops such as Camellia japonica L. to speed up growth reducing the nursery. The experiments were performed on flowering camellia, using non-rooted cuttings treated with Actiwave® (Valagro Spa) and gibberillic acid (GA3). The Actiwave was applied providing 0.015 or 0.03 ml per cutting, while the GA3 was applied 1.25 or 2.5 mg per cutting. Treatments were repeated each month with eight applications in total. The biostimulant was distributed on the substrate with a volume of 100 ml. The GA3 instead was nebulized on the leaves and on the substrate of each cutting. Rooting was monitored during the whole experimental period. The measurements of fresh and dry weight were taken after 127 days. Results showed that both Actiwave® and GA3 stimulated the rooting compared with control. The two concentrations of Actiwave® had the same effect, with an average fresh root mass of 0.5 g. The treatment with GA3 was observed for a dose-effect response. The differences in dry weight were observed only on roots, and values were significantly higher in the treatments compared to the control
Stress abiotici e bilancio ormonale nelle piante coltivate
No full textAbiotic stresses cause extensive losses to agricultural production worldwide. The most important abiotic stresses, i.e. those causing main losses of productivity, are induced by water deficiency, high salinity, high or low temperatures and nutient deficiency. From a strictly agronomic point of view, however, we must consider as relevant also other stresses, such as hypoxia due to waterlogging , excessive concentrations of nutrients or the presence of heavy metals in the soil, mechanical perturbation due to intense meteoric events (rain, wind and hail) or to the manipulation to which plants are subjected during cultivation, post production handling and storage. Particular stress conditions are those due to the reduced substrate volume (root restriction), and the elevate plant density, which causes the so-called “shade avoidance syndrome”. These last two stresses are particularly important in nursery and in pot plant production.
Plants are able to perceive environmental stimuli and to adapt to different environments, however, the degree of tolerance and adaptability to abiotic stresses varies among species and varieties. Plant hormones are involved in the response to environmental stresses, in many cases acting as chemical messengers and triggering metabolic pathways leading to the acquisition of stress tolerance. It is now widely accepted that abscisic acid (ABA) plays a major role in the physiological changes induced by environmental stresses and endogenous ABA levels significantly increase in response to many environmental stimuli. Also other hormones, however, play an important role in many stress situations, such as ethylene, whose biosynthesis can be considered as a physiological marker of plant health status, or cytokinins which mediate many responses of the plant to abiotic stresses, often interacting with abscisic acid, auxins and ethylene.
The present paper is aimed to analyze the role of endogenous plant hormones in the plant response to different environmental stresses. For each hormone, after a brief description, which also deals with the basic biochemical aspects, we focused our attention on particular stress situations pointing out the possible interactions with other hormones and presenting simple physiological models.of the mechanism of stress tolerance acquisition
Changes in abscisic acid during leaf yellowing of cut stock flowers
No full textLeaf pigments, such as chlorophyll and carotenoids, are essential plant molecules. They provide carbohydrates
and energy during all plant life. Leaf pigments are also important parameters of decorative plants,
such as floriculture items, cut foliage and flowers. Leaf yellowing is a form of senescence caused by an
internal hormone imbalance, such as a lack of cytokinins. The aim of this study was to investigate the
changes in total carotenoids and endogenous ABA in cut flower stock leaves during post-harvest life. The
effect of pulse treatment with 5 or 10 lM thidiazuron (TDZ), 150 mg l 1 8-hydroxyquinoline sulphate
(8-HQS) and combinations of TDZ with 8-HQS on total carotenoids and ABA concentration was also
investigated. Results showed that total carotenoids drastically decreased from 1548 lg cm 2, until reaching
565 lg cm 2 at the end of vase life. Endogenous ABA strongly increased at the same time, going from
167 ng g 1 DW at the beginning of the experiment to 1322 ng g 1 DW at the end of vase life. The TDZ
inhibited carotenoid degradation, but did not affect the ABA concentration, while the 8-HQS did not
prevent carotenoid degradation and the ABA concentration was only slightly affected. ABA seems to be a
secondary senescence bio-product that may have a synergic effect with other senescence inducers dramatically
accelerating leaf senescence
Impiego di biostimolanti naturali su specie da bordura e riduzione dell’apporto di fertilizzanti in vivaio
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