Factors Determining Petal Colour of Baccara Roses II: THE EFFECT OF PIGMENT CONCENTRATION

‘Blueing’ in young and senescing petals was comparedin the red rose cv. Baccara. The ‘blueing’ of senescingflowers is accompanied by a bathochromic shift in the lightreflectance curve, a rise in the pH value and a decrease inthe malic acid concentration of the petal tissue. These factorsindicate that a complex with a co-pigment is produced. Similarchanges were not found in the ‘blueing’ of youngflowers, where a decrease was found in pigment concentrationper unit weight as well as per unit area of petal. A similar‘blueing’ was achieved by diluting a solution ofcrystalline cyanin. The phenomenon of ‘blueing’by dilution is discussed in the light of Bougeur's law.     

Factors determining Petal Colour of Baccara Roses I: THE CONTRIBUTION OF EPIDERMIS AND MESOPHYLL

The partition of light radiated on to the outer epidermis ofa Baccara rose petal or on to an intact petal was examined.Most of the red light was either reflected or transmitted whereasother wavelengths and especially the green range were absorbed.When the total amount of light transmitted (epidermis) or reflected(intact petal) increased, a rise in the blue range was recordedand the colour of the petal, determined objectively by CIE orMunsell's method, became more purple. Examination of the partition of light in the different layersof the petal revealed that light reflected from the outer epidermisis made up of two parts; one part is reflected directly andthe other part is first transmitted through the epidermis, reachesthe mesophyll, is reflected from it and is then transmittedthrough the epidermis. This latter part causes a shift in colourfrom purple to red. Colour differences between different petals on one flower anddifferent parts of the same petal were defined objectively.The change from red to purple colour was connected with vigorousgrowth of either the petal or epidermal cells, respectively. The contribution of the mesophyll in changing the reflectancecurve of petals is explained and it is suggested that althoughthe mesophyll is colourless, it contributes to a great extentto the changes occurring in petal colour.     

Factors determining Petal Colour of Baccara Roses III: EFFECT OF THE RATIO BETWEEN CYANIN AND PELARGONIN

The changes in colour and in the pigment concentration of thetwo sides of Baccara rose petals which occur when plants aregrown under various temperature regimes, were examined. Theinner side of the petal is redder and the predominant pigmentis pelargonin whereas the outer petal surface tends to ‘blue’,and, the predominant pigment on this side is cyanin. The cyanin:pelargonin ratio on the outer side of petals increased three-foldunder the influence of low temperatures. The outer surface of petals growing for a long period underlow tempertaures was ‘blue’ when compared with thered petals which had been subjected to low temperatures fora short period. The cyanin: pelargonin ratio of ‘blue’petals was higher than that of red petals. Total pigment contentwas similar in both types of petal. Flowers grown under hightemperatures ‘blued’ without a concomitant fallin the cyaninpel: argonin ratio. Examination of colour solutions in which the ratio between cyaninand pelargonin was varied revealed that the colour of the solutionbecame bluer as this ratio increased. We suggest that the ‘blueing’ of Baccara rose petalsis caused primarily by a dilution of the cyanin content, butwhen the ratio between cyaniri and pelargonin increases sharply,‘blueing’ may also occur in dark flowers in whichthe total pigment content did not diminish.     

Effects of Varying Light Intensities and Temperature Treatments Applied to Whole Plants, or Locally to Leaves or Flower Buds, on Growth and Pigmentation of 'Baccara' Roses

Varying light intensity and temperature treatments were applied to whole plants, or to the leaves, or to the flower buds of ‘Baccara’ roses. The effect of these treatments on flower dimensions and pigmentation of the petals was examined. Cooling only the leaves had no effect; cooling only the buds enhanced both bud weight and pigmentation, but the effect was less marked than when the whole plant was cooled. Reducing plant temperature by misting with desalinated water enhanced both pigmentation and flower size. Darkening of only the leaves, or their removal, resulted in an inhibition of the pigmentation and also in a decrease in bud weight. Darkening of only the flower bud did not affect either pigmentation or bud weight, but caused bud elongation. It is suggested that light intensity and temperature affect flower growth and pigmentation via their effects on the availability of sugars in the flower bud.     

Photosynthetic Responses of Four Hosta Cultivars to Shade Treatments

The effects of shade on the gas exchange of four Hosta cultivars were determined under differing irradiances (5, 30, 50, and 100 % of full irradiance) within pots. Irradiance saturation ranged between 400–800 mol m^–2 s^–1 among the four cultivars, of which H. sieboldiana cv. Elegans and H. plantagenea cv. Aphrodite exerted the lowest saturation and compensation irradiances. The maximal photosynthetic rate (P _max) was significantly higher in shade than in full irradiance in Elegans and Aphrodite, and was at maximum in seedlings grown in 30 % of full irradiance. The best shade treatment for cvs. Antioch and Golden Edger was 50 % of full irradiance. The diurnal gas exchange patterns in four cultivars were greatly influenced by the irradiance. Single-peak patterns of net photosynthetic rate (P _N) and stomatal conductance (g _s) were observed under 5 and 30 % full irradiance for all the cultivars while Elegans and Aphrodite suffered from midday depression in 50 % of full irradiance. Under open sky, all four cultivars showed two-peak patters in their diurnal gas exchange, but the midday depression was less in Antioch and Golden Edger than in Elegans and Aphrodite. According to their photosynthetic responses to shade, the shade tolerance of the four cultivars was in the order: Elegans>Aphrodite>Antioch>Golden Edger.     

The Effect of Canopy Wetting on Plant Water Status, CO2 Fixation, Ion Content and Growth Rate of 'Baccara' Roses

The effect of canopy wetting of rose (Rosa hybrida) plants on transpiration rate, stomatal resistance, plant water potential, ion concentration in leaves, and several growth parameters was investigated. Plants were grown in a greenhouse and their canopies were exposed to wetting cycles during the daytime. Canopy wetting decreased transpiration rate and increased diffusive resistance to water vapor transfer. Plant water potential was only slightly increased by wetting, mainly in the spring. Canopy wetting did not prevent the decrease in CO₂ fixation, which took place before midday when plant water potential dropped below – 10 bars during a rise in radiation intensity. The concentrations of Cl^? and Ca²⁺ decreased in wetted leaves, while the concentration of Na⁺ was increased and other cations were hardly affected. Canopy wetting inhibited growth rate of rose shoots and flower formation, and increased the average flower weight.     

Anthocyanins in Modern Roses: Chemical and Colorimetric Features in Relation to the Colour Range

With respect to intravarietal variability, the petals of 15rose (Rosa x hybrida) varieties, representative of the colourrange expressed by modern roses primarily pigmented with anthocyanins,were investigated from chemical and. colorimetric viewpoints.Depending on the variety, the observed colour variations werebased on a more or less complex mixture of cyanidin 3,5-diglucoside,pelargonidin 3,5-diglucoside, quercetin and kaempferol glycosides.The total anthocyanin content ranged from 4 to 109 mg g^–1petal dry wt., while the total amount of flavonol glycosideswas never less than 8 mg g^–1 and could reach 136 mg g^–1petal dry wt. Between cultivars, the pH of the petal outer epidermisvaried from 3·6 to 5·4 units. Using a spectrocolorimeter,the petal colour of each variety was measured. In order to allowquantitative comparisons of colours, the reflectance curveswere further translated into indices calculated using the CIELabsystem. In the aggregate, there were good correlations betweenchemical parameters and colorimetric indices that are lightness(L^*), chroma (C^*) and hue angle (h). Both of these criteria(chemical and colorimetric) appeared sufficient to explain thevisual sense of the petal colour. Key words: Rose, colour, flavonoid, colorimetry, CIELab system     

Studies on the Glasshouse Carnation: Effects of Temperature and Growth Substances on Petal Number

A low temperature (5 ?C) given either continuously or at nightpromoted the formation of secondary growing centres within theflower of carnation. Additional petals were produced from thesecentres and hence the total petal number was markedly increased.The formation of secondary growing centres and additional petalscould also be promoted by application of GA₃or IAA to the shoottip during flower initiation. Increases in the number of petalsarising directly from the receptacle were produced by a localizedhigh temperature treatment of the shoot tip or by applicationof kinetin. Effects of temperature on petal number were exertedin the early stages of flower development before the flowerbud became visible between the leaves.     

Effects of a Daily Short-Term Temperature Drop on Chilling-Sensitive and Cold-Resistant Plants

Russian Journal of Plant Physiology - A set of physiological and biochemical parameters (leaf growth rate, plant biomass, chlorophyll content, rates of photosynthesis and transpiration, relative...     

Short-Term Effects of Particulate Matter on Stroke Attack: Meta-Regression and Meta-Analyses

Background and Purpose

Currently there are more and more studies on the association between short-term effects of exposure to particulate matter (PM) and the morbidity of stroke attack, but few have focused on stroke subtypes. The objective of this study is to assess the relationship between PM and stroke subtypes attack, which is uncertain now.

Methods

Meta-analyses, meta-regression and subgroup analyses were conducted to investigate the association between short-term effects of exposure to PM and the morbidity of different stroke subtypes from a number of epidemiologic studies (from 1997 to 2012).

Results

Nineteen articles were identified. Odds ratio (OR) of stroke attack associated with particular matter (“thoracic particles” [PM₁₀]<10 µm in aerodynamic diameter, “fine particles” [PM_2.5]<2.5 µm in aerodynamic diameter) increment of 10 µg/m³ was as effect size. PM₁₀ exposure was related to an increase in risk of stroke attack (OR per 10 µg/m³ = 1.004, 95%CI: 1.001∼1.008) and PM_2.5 exposure was not significantly associated with stroke attack (OR per 10 µg/m³ = 0.999, 95%CI: 0.994∼1.003). But when focused on stroke subtypes, PM_2.5 (OR per 10 µg/m³ = 1.025; 95%CI, 1.001∼1.049) and PM₁₀ (OR per 10 µg/m³ = 1.013; 95%CI, 1.001∼1.025) exposure were statistically significantly associated with an increased risk of ischemic stroke attack, while PM_2.5 (all the studies showed no significant association) and PM₁₀ (OR per 10 µg/m³ = 1.007; 95%CI, 0.992∼1.022) exposure were not associated with an increased risk of hemorrhagic stroke attack. Meta-regression found study design and area were two effective covariates.

Conclusion

PM_2.5 and PM₁₀ had different effects on different stroke subtypes. In the future, it''s worthwhile to study the effects of PM to ischemic stroke and hemorrhagic stroke, respectively.     

Effects of Foliar Sprays of Phosphates on Powdery Mildew (Sphaerotheca pannosa) of Roses

Powdery mildew on plants of a local clone of Rosa indica Major was significantly controlled by a single spray of 25 mM aqueous solutions of K₂HPO₄, KH₂PO₄ plus KOH, or NaHCO₃, all plus Tween 20 (0.5 ml/l) or bupirimate (Nimrod) at 0.5 ml/l, which was applied 4 days before inoculation with conidial suspension of Sphaerotheca pannosa var. rosae. Disease incidence was reduced by 79, 71, 54 and 50%, as compared to controls on plants sprayed with KH₂PO₄ plus KOH, K₂HPO₄, NaHCO₃ or bupirimate, respectively. Phosphates were suppressive and expressed by disappearance of 99% of the pustules and conidia, as early as 2 days after a single spray on mildewed foliage. This treatment was efficient for at least 9 days after the first application when large infected greenhouse-grown plants were used. Re-application of these salts on the same plants reduced the lesion area by about 90% from that recorded before the application. Phosphate and bicarbonate were more suppressive than the systemic fungicide bupirimate in the early period (up to 2 days). The suppresion effects of bicarbonate and bupirimate, however, were short-term and not persistent, while the phosphate treatments remained significantly suppressive for up to 23 days, when the experiment was terminated. The inhibitory and suppressive effectiveness of phosphate salts is discussed in the light of their possible acceptance as ideal foliar fertilizers which should be considered for use in the field for disease control.     

Effects of Foliar Sprays of Phosphates on Powdery Mildew (Sphaerotheca pannosa) of Roses

Powdery mildew on plants of a local clone of Rosa indica Major was significantly controlled by a single spray of 25 mM aqueous solutions of K₂HPO₄, KH₂PO₄ plus KOH, or NaHCO₃, all plus Tween 20 (0.5 ml/l) or bupirimate (Nimrod) at 0.5 ml/l, which was applied 4 days before inoculation with conidial suspension of Sphaerotheca pannosa var. rosae. Disease incidence was reduced by 79, 71, 54 and 50%, as compared to controls on plants sprayed with KH₂PO₄ plus KOH, K₂HPO₄, NaHCO₃ or bupirimate, respectively. Phosphates were suppressive and expressed by disappearance of 99% of the pustules and conidia, as early as 2 days after a single spray on mildewed foliage. This treatment was efficient for at least 9 days after the first application when large infected greenhouse-grown plants were used. Re-application of these salts on the same plants reduced the lesion area by about 90% from that recorded before the application. Phosphate and bicarbonate were more suppressive than the systemic fungicide bupirimate in the early period (up to 2 days). The suppresion effects of bicarbonate and bupirimate, however, were short-term and not persistent, while the phosphate treatments remained significantly suppressive for up to 23 days, when the experiment was terminated. The inhibitory and suppressive effectiveness of phosphate salts is discussed in the light of their possible acceptance as ideal foliar fertilizers which should be considered for use in the field for disease control.     

Effect of Combined Salt and Heat Treatments on Germination and Heat-Shock Protein Synthesis in Lentil Seeds

The germination of lentil seeds was gradually reduced when seeds were exposed to temperature of 30 or 40 °C, either alone or combined with 0.1, 0.2 or 0.3 M NaCl or 34.1 % (m/v) PEG 8000, during 6 –12 h imbibition. [³⁵S]-methionine incorporation in 12 h imbibed lentil axes also decreased with increasing NaCl concentration at 20 and 40 °C, whereas at 30 °C only 0.3 M NaCl treatment partially inhibited protein synthesis. An analysis of newly synthesized proteins by 1-D SDS PAGE, showed that the expression of most polypeptides decreased following increasing stress. Among these, low molecular mass heat-shock proteins declining, higher in 40 °C treated axes than those treated at 30 °C, supports the hypothesis that at this temperature maximal level of expression of these proteins was achieved.     

Cumulative Effects of Short-Term Polymetal Contamination on Soil Bacterial Community Structure

In this study we evaluated the short-term effects of copper, cadmium, and mercury, added singly or in combination at different doses, on soil bacterial community structure using the bacterial automated ribosomal intergenic spacer analysis (B-ARISA) fingerprinting technique. Principal-component analysis of B-ARISA profiles allowed us to deduce the following order of impact: (Cu + Cd + Hg) >> Hg ≥ Cd > Cu. These results demonstrated that there was a cumulative effect of metal toxicity. Furthermore, the trend of modifications was consistent with the “hump-backed” relationships between biological diversity and disturbance described by Giller et al. (K. E. Giller, E. Witler, and S. P. McGrath, Soil Biol. Biochem. 30:1389-1414, 1998).     

The Effects of Drought and Shade on the Performance,Morphology and Physiology of Ghanaian Tree Species

In tropical forests light and water availability are the most important factors for seedling growth and survival but an increasing frequency of drought may affect tree regeneration. One central question is whether drought and shade have interactive effects on seedling growth and survival. Here, we present results of a greenhouse experiment, in which seedlings of 10 Ghanaian tree species were exposed to combinations of strong seasonal drought (continuous watering versus withholding water for nine weeks) and shade (5% irradiance versus 20% irradiance). We evaluated the effects of drought and shade on seedling survival and growth and plasticity of 11 underlying traits related to biomass allocation, morphology and physiology. Seedling survival under dry conditions was higher in shade than in high light, thus providing support for the “facilitation hypothesis” that shade enhances plant performance through improved microclimatic conditions, and rejecting the trade-off hypothesis that drought should have stronger impact in shade because of reduced root investment. Shaded plants had low biomass fraction in roots, in line with the trade-off hypothesis, but they compensated for this with a higher specific root length (i.e., root length per unit root mass), resulting in a similar root length per plant mass and, hence, similar water uptake capacity as high-light plants. The majority (60%) of traits studied responded independently to drought and shade, indicating that within species shade- and drought tolerances are not in trade-off, but largely uncoupled. When individual species responses were analysed, then for most of the traits only one to three species showed significant interactive effects between drought and shade. The uncoupled response of most species to drought and shade should provide ample opportunity for niche differentiation and species coexistence under a range of water and light conditions. Overall our greenhouse results suggest that, in the absence of root competition shaded tropical forest tree seedlings may be able to survive prolonged drought.     

The Effect of Gibberellins on Flowering in Roses

The gibberellins A₁, A₃, A₅, A₈, A₁₉, A₂₀, and A₂₉ were identified in vegetative shoot tips of Rosa canina by comparing their mass spectra and Kovats retention indices with those of standards. Most wild roses have a short flowering season of 2–4 weeks in spring, whereas most modern cultivars flower recurrently. `Félicité et Perpétue' is a short-season hybrid from a cross between a wild rose and a recurrent-flowering rose, whereas its sport, `Little White Pet,' flowers recurrently. The concentrations of gibberellins (GAs) were measured in shoot apices of both cultivars. In March (before floral initiation in spring) the concentrations of GA₁ and GA₃ were respectively threefold and twofold higher in `Félicité et Perpétue' than in `Little White Pet.' In April (after floral initiation) the concentrations of both gibberellins were substantially greater than in March, and concentrations of GA₁ and GA₃ were, respectively, 17-fold and 12-fold greater in `Félicité et Perpétue' than in `Little White Pet.' It is postulated that, in `Félicité et Perpétue,' floral initiation occurs when concentrations of GAs are low and is inhibited when concentrations of GAs are high, whereas in `Little White Pet' concentrations of GAs remain at permissive levels throughout the growing season. Applications of GA₁ and GA₃ to axillary shoots in March inhibited floral development in `Félicité et Perpétue' but not in `Little White Pet.' This suggests that the combined concentration of exogenous and endogenous gibberellins might have been raised to inhibitory levels in the former but not in the latter cultivar. Received January 10, 1999; accepted June 16, 1999