Non-destructive analysis of photosynthetic pigments in cotton plants
Relationship between Chlorophylls and Carotenoids of Ripening Tomato Fruit as Influenced by. Potassium Nutrition1. M. J. TRUDEL2 AND J. L. OZBUN. Chlorophyll and carotenoids are both pigments, or chromophores, that are involved in photosynthesis. Both chlorophyll and carotenoids are. What is the relationship between chlorophyll-a and carotenoids? Carotenoids are accessory pigments that help chlorophyll-a capture light energy during.
The chlorophyll extraction and greenness reading indexes were obtained from leaves harvested at the base of the petiole and placed in plastic zip-loc bags that were kept in the dark and cool until arrival at the laboratory. All samples were processed within approximately 2 hours after being gathered in the field.
Chlorophyll meter readings Leaf disks were randomly sampled from leaves using a borer with a diameter of Approximately leaf discs were used, and the values obtained by the meters varied from 4 to 60, making the maximum amplitudes between value readings.
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Photosynthetic pigment analysis After obtaining the meter readings, the chlorophyll was extracted from the leaf disks using the Hiscox and Israelstam procedure. Each disc was cut into smaller pieces and placed in a test tube containing 5 mL of dimethyl sulfoxide DMSO.
After cooling, a 3-mL aliquot of the chlorophyll extract was transferred to a cuvette for the determination of the chlorophyll absorbance using a spectrophotometer atand nm.
Absorption measurements were used to quantify the chlorophyll a, chlorophyll b, and total chlorophyll concentrations, based on the equations reported by Wellburn The mathematical equations were adjusted with a high coefficient of determination.
The readings for the greenness indexes were used as the dependent variable, while the pigment concentrations extracted by the classical method were used as the independent variable. Data analyses were conducted using SigmaPlot A Pearson correlation analysis between the two portable chlorophyll meters readings was conducted.
Results and discussion Despite the fact that the two portable meters provided different values for the chlorophyll measurements, we observed a high correlation between their data Figure 1.
It was observed that this difference was higher in leaves that presented less chlorophyll content spectrophotometrically, namely, with the lower readings with the devices.
Consequently, it was necessary to perform distinct adjustments in the mathematical models for the prediction of chlorophyll and carotenoid content by each portable meter. We suggest that it is likely that such differences occurred because these two devices operate in different wavelength ranges.
According to Markwell et al. In contrast, the Clorofilog functions with LEDs in wavelengths ofand nm. Figures 2 and 3 show the relationships between the readings obtained in cotton leaves by the two chlorophyll meters and the concentrations of chlorophylls a and b, respectively.
The relationship between the chlorophyll readings from both portable meters and the contents of chlorophyll a and chlorophyll b was more readily expressed with a quadratic model. Determination coefficients of the adjusted models were 0.
The relationship between the chlorophyll readings in both portable meters and the concentrations of carotenoids were fit in a quadratic model, and an R2 value of 0. The relationship between the readings and total chlorophyll are presented in Figures 4b and 5band a high R2 value was obtained. The coefficient of determination for the adjusted models of total chlorophyll content was 0. The relationship between the photosynthetic pigment concentration and the chlorophyll readings have been established for several species of plants, such as the total chlorophyll in Glycine max and Zea mays MARKWELL et al.
The readings obtained by both chlorophyll meters allowed for the estimation of these relationships between chlorophyll and carotenoids via an indirect, though highly precise method. The quadratic mathematical model provided a better representation, with determination coefficients of 0. The relationship between chlorophyll and carotenoids has been much less used, although this ratio may be considered a good indicator to distinguish between natural senescence and senescence as a result of environmental injuries, such as desiccation in mosses BUCKLAND et al.
Measurements of less than 40 indicate the beginning of a possible reduction in photosynthetic processes. This effect was also observed by Torres Neto et al. Similar to the other characteristics analyzed, the quadratic mathematical model best fit the data, exhibiting determination coefficients above 0.
Conclusion In general, it was observed that the use of the portable chlorophyll meters, SPAD and Clorofilog, produced results associated with empirical models and allowed for a quick prediction of the concentration of photosynthetic pigments in the leaves of cotton, with high accuracy and without the use of chemical reagents and extensive laboratory protocols.
The relationship between chlorophyll and the carotenoids in the algal flagellate, Euglena.
Photoregulation of the composition, function, and structure of thylakoid membranes. Annual Review of Plant Physiology, v. Comparative photosynthesis of sun and shade plants. A comment on the spectrophotometric determination of chlorophyll.
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- THE RELATIONSHIP BETWEEN CHLOROPHYLL AND THE CAROTENOIDS IN THE ALGAL FLAGELLATE, EUGLENA
- The relationship between chlorophyll and the carotenoids in the algal flagellate, Euglena.
- Light and photosynthetic pigments
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Accessory pigments are required to fill this absorption gap. Ad A second limitation of chlorophylls arises out of the very characteristic that makes them such powerful pigments in the photosynthetic system: That ability, however, also leads to a tendency to generate toxic reactive oxygen species.
Again, accessory pigments, carotenoids in particular, are able to help solve this problem. Carotenoids are chromophores that are usually red, orange or yellow in color.
Chlorophyll - Wikipedia
The most well-known carotenoid is probably carotene, which gives carrots their orange color. Carotenoids have two main functions: For their primary function, carotenoids absorb light energy from photons. Protochlorophyllide In plants, chlorophyll may be synthesized from succinyl-CoA and glycinealthough the immediate precursor to chlorophyll a and b is protochlorophyllide.
In Angiosperm plants, the last step, the conversion of protochlorophyllide to chlorophyll, is light-dependent and such plants are pale etiolated if grown in darkness. Non-vascular plants and green algae have an additional light-independent enzyme and grow green even in darkness. Chlorophyll itself is bound to proteins and can transfer the absorbed energy in the required direction.
Protochlorophyllide occurs mostly in the free form and, under light conditions, acts as a photosensitizerforming highly toxic free radicals.How are carotenoid pigments different from chlorophyll
Hence, plants need an efficient mechanism of regulating the amount of chlorophyll precursor. In angiosperms, this is done at the step of aminolevulinic acid ALAone of the intermediate compounds in the biosynthesis pathway. Plants that are fed by ALA accumulate high and toxic levels of protochlorophyllide; so do the mutants with the damaged regulatory system. Chlorosis Chlorosis is a condition in which leaves produce insufficient chlorophyll, turning them yellow.
Chlorosis can be caused by a nutrient deficiency of iron — called iron chlorosis — or by a shortage of magnesium or nitrogen.