chlorophyll-a and paclobutrazol

Basil (Ocimum basilicum) is a medicinal, ornamental and aromatic plant, however, its size can be an obstacle to its commercialization as a potted ornamental plant. Paclobutrazol (PBZ) is a substance that can retard plant growth by inhibiting the synthesis of gibberellins. The objective of this work was to evaluate the effect of paclobutrazol on growth regulation and gas exchange of basil (var. Cinnamon). The experiment was carried out in a completely randomized design with five treatments (PBZ doses: 0, 2.5, 5, 7.5 and 10 mg L-1), with eight replicates. Growth (plant height, number of leaves, stem diameter, leaf dry mass, stem dry mass, inflorescence dry mass, and total), growth rates (leaf mass ratio, stem mass ratio, inflorescence mass ratio, and robustness quotient), chlorophyll indices, gas exchange (gs, A, E, Ci, WUE, iWUE and iCE) were evaluated. Paclobutrazol reduced the growth of basil plants and increased the chlorophyll indices, A, gs, and WUE. Paclobutrazol can be used to regulate plant growth of basil plants var. Cinnamon, without altering its physiological and ornamental characteristics.

Topics: Chlorophyll; Ocimum basilicum; Plant Leaves; Triazoles

The environmental behavior of paclobutrazol in soil and its toxicity were studied by field investigation and an outdoor pot experiment, and the residue of paclobutrazol was detected by gas chromatography-mass spectrometry. Field investigation has found that the residual paclobutrazol in the former succession crop could severely inhibit the growth of succeeding crops of potato; with migration and transformation of residual paclobutrazol in the soil, the stems of potato were thickened with residual amount of 1.23 mg kg

Topics: Catalase; Chlorophyll; Colocasia; Gas Chromatography-Mass Spectrometry; Plant Leaves; Plant Proteins; Seedlings; Soil; Soil Pollutants; Solanum tuberosum; Superoxide Dismutase; Triazoles

Drought stress is the major limiting factor which affects turfgrass management in area with restricted rainfall or irrigation water supply. Trinexapac ethyl (TE), Paclobutrazol (PAC) and Abscisic acid (ABA) are three plant growth regulators (PGRs) that are commonly used on turf species for increasing their tolerance to different environmental stresses such as drought. However, little is known about the impact of PGRs on stress tolerance of Iranian Perennial ryegrass (Lolium perenne). The present study was conducted to examine the visual and physiological changes of Iranian Perennial ryegrass in response to foliar application of TE, PAC, and ABA under drought stress conditions. According to the obtained results, application of all three PGRs considerably restored visual quality of drought exposed plants. TE treatment increased chlorophyll content, proline content and resulted in less malondialdehyde (MDA) in drought stressed Perennial ryegrass. Application of all PGRs enhanced the relative water content (RWC) and decreased the electrolyte leakage (EL) and Hydrogen peroxide contents (H

Topics: Abscisic Acid; Antioxidants; Carbohydrates; Chlorophyll; Cyclopropanes; Electrolytes; Gene Expression Profiling; Gene Expression Regulation, Plant; Hydrogen Peroxide; Lolium; Malondialdehyde; Plant Leaves; Proline; Quinones; Real-Time Polymerase Chain Reaction; Solubility; Stress, Physiological; Triazoles; Water

Salicylic acid (SA) is an important plant hormone, and its exogenous application can induce tolerance to multiple environmental stresses in plants. In this study, we examine the potential involvement of endogenous SA in response to chilling in cucumber (Cucumis sativus L.) seedlings. A low temperature of 8 °C induces a moderate increase in endogenous SA levels. Chilling stimulates the enzymatic activities and the expression of genes for phenylalanine ammonia-lyase (PAL) and benzoic acid-2-hydroxylase rather than isochorismate synthase. This indicates that the PAL enzymatic pathway contributes to chilling-induced SA production. Cucumber seedlings pretreated with SA biosynthesis inhibitors accumulate less endogenous SA and suffer more from chilling damage. The expression of cold-responsive genes is also repressed by SA inhibitors. The reduction in stress tolerance and in gene expression can be restored by the exogenous application of SA, confirming the critical roles of SA in chilling responses in cucumber seedlings. Furthermore, the inhibition of SA biosynthesis under chilling stress results in a prolonged and enhanced hydrogen peroxide (H2O2) accumulation. The application of exogenous SA and the chemical scavenger of H2O2 reduces the excess H2O2 and alleviates chilling injury. In contrast, the protective effects of SA are negated by foliar spraying with high concentrations of H2O2 and an inhibitor of the antioxidant enzyme. These results suggest that endogenous SA is required in response to chilling stress in cucumber seedlings, by modulating the expression of cold-responsive genes and the precise induction of cellular H2O2 levels.

Topics: Antioxidants; Chlorophyll; Cold Temperature; Cucumis sativus; Hydrogen Peroxide; Phenylalanine; Phenylalanine Ammonia-Lyase; Plant Growth Regulators; Plant Proteins; Salicylic Acid; Seedlings; Stress, Physiological; Triazoles

Camelina (Camelina sativa L. Crantz) is a non-food oilseed crop which holds promise as an alternative biofuel energy resource. Its ability to grow in a variety of climatic and soil conditions and minimal requirements of agronomical inputs than other oilseed crops makes it economically viable for advanced biofuel production. We designed a study to investigate the effect of paclobutrazol [2RS, 3RS)-1-(4-Chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol] (PBZ), a popular plant growth regulator, on the seed and oil yield of Camelina sativa (cv. Celine).. A field-based micro-trial setup was established in a randomized block design and the study was performed twice within a span of five months (October 2010 to February 2011) and five different PBZ treatments (Control: T0; 25 mg l-1: T1; 50 mg l-1: T2; 75 mg l-1: T3; 100 mg l-1: T4; 125 mg l-1: T5) were applied (soil application) at the time of initiation of flowering. PBZ at 100 mg l-1 concentration (T4) resulted in highest seed and oil yield by 80% and 15%, respectively. The seed yield increment was mainly due to enhanced number of siliques per plant when compared to control. The PBZ - treated plants displayed better photosynthetic leaf gas exchange characteristics, higher chlorophyll contents and possessed dark green leaves which were photosynthetically active for a longer period and facilitated higher photoassimilation.. We report for the first time that application of optimized PBZ dose can be a potential strategy to achieve higher seed and oil yield from Camelina sativa that holds great promise as a biofuel crop in future.

Topics: Biofuels; Brassicaceae; Chlorophyll; Dose-Response Relationship, Drug; Photosynthesis; Plant Growth Regulators; Plant Leaves; Plant Oils; Seasons; Seeds; Soil; Triazoles

The effects of gibberellin A(3) (GA(3)) on natural senescence and the relationship between gibberellins (GAs), abscisic acid (ABA), and senescence are not fully understood. For example, it is still unclear whether GA and ABA act antagonistically. There are only few reports on senescence-related changes in physiological parameters of herbaceous perennials. This study was designed to investigate the effects of exogenous GA(3) on the senescence of aerial parts in a herbaceous perennial species, Paris polyphylla, and to test the hypothesis that GA and ABA display antagonistic effects in this process. Physiological changes associated with senescence, in particular of the hormonal and oxidative metabolisms, were also investigated. GA(3) was sprayed on mature leaves at weekly intervals, which significantly impeded senescence of aerial parts and slowed the decline of pigments and total soluble protein. Treated plants suffered less oxidative stress as revealed by reduced lipid peroxidation, a lower hydrogen peroxide level and modified activities of superoxide dismutase, peroxidase, ascorbate peroxidase, and their respective isozyme profiles. In GA(3) treated plants GA(4)+GA(7) (GAs) levels increased progressively and became significantly higher than those of control plants, whereas ABA increased in controls. When plants were treated with GA-synthesis inhibitor paclobutrazol (PCB), GAs decreased, ABA increased, and senescence was promoted. Application of a mixture of GA(3) and PCB restored the accumulation of GAs, reduced ABA, and ultimately senescence was delayed. These results suggest that GA and ABA play antagonistic roles in the senescence of aerial parts in P. polyphylla, and this process is associated with oxidative stress and regulated by endogenous hormones and extrinsic factors. Possible mechanisms that control this GA(3)-mediated inhibition of senescence are discussed.

Topics: Abscisic Acid; Ascorbate Peroxidases; Biomarkers; Carotenoids; Chlorophyll; Gibberellins; Hydrogen Peroxide; Isoenzymes; Magnoliopsida; Malondialdehyde; Models, Biological; Oxidative Stress; Peroxidases; Plant Components, Aerial; Plant Leaves; Solubility; Superoxide Dismutase; Temperature; Time Factors; Triazoles; Vapor Pressure

Effect of growth retardants (paclobutrazol or ancymidol) was studied in Lilium plantlets growing in liquid culture. A significant increase in leaf chlorophyll, epicuticular wax, plant dry weight and bulb starch contents were found in plantlets treated with growth retardants. A similar increase in the number of leaves, roots and bulbs was also noted. However, total leaf area and the fresh weight increased only marginally. These features resulted in robust plantlets that showed significantly improved ex vitro survival. Based on these features, a comprehensive index (CI) was calculated as a measure of quality of the plantlets, and it correlated well with their ex vitro survival. Treatment of plantlets with 3.4 microM paclobutrazol was found to be the best and its carry over effects were also minimal.

Topics: Bioreactors; Chlorophyll; Culture Techniques; Lilium; Plant Growth Regulators; Plant Leaves; Pyrimidines; Starch; Triazoles

In fertilized flowers of Helleborus niger L., the sepals (the showy elements of the perianth at anthesis) grow, spread, and turn green, and the peduncles elongate. These processes did not proceed to completion when the pistils were removed at the bud stage, but could be restored by the application of plant growth regulators. Cytokinins and gibberellins stimulated the formation of well-developed chloroplasts in, and spreading of, the sepals; the gibberellin, GA3, and the auxin, 4-chloroindole-3-acetic acid, promoted peduncle elongation. In fruit-bearing flowers, on the other hand, paclobutrazol, an inhibitor of gibberellin biosynthesis, reduced chlorophyll formation in the sepals, reversed sepal spreading, and inhibited peduncle elongation. Of the endogenous growth regulators in developing fruit, the following cytokinins were identified: zeatin, dihydrozeatin, N6-(2-isopentenyl)adenine and their ribosides and 9-glucosides. Zeatin riboside drastically increased in abundance (about 200 times), shortly after fertilization, when chlorophyll accumulation in the sepals occurred at the fastest rate, and remained the most prominent identified cytokinin until seed ripening.

Topics: Algorithms; Chlorophyll; Cytokinins; Fruit; Gibberellins; Indoleacetic Acids; Microscopy, Electron; Morphogenesis; Plant Growth Regulators; Plant Stems; Plastids; Ranunculaceae; Reproduction; Triazoles