scholarly journals ASPECTOS BIOQUÍMICOS E FLUORESCÊNCIA DA CLOROFILA A EM PLANTAS DE MINIMELANCIA HIDROPÔNICA SOB ESTRESSE SALINO*

Irriga ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 221-239
Author(s):  
Laís Monique Gomes do Ó ◽  
Alide Mitsue Watanabe Cova ◽  
Petterson Costa Conceição Silva ◽  
Hans Raj Gheyi ◽  
André Dias de Azevedo Neto ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Chlorophyll A ◽  
Soluble Carbohydrates ◽  
Chlorophyll B ◽  
Sodium Potassium ◽  
Hydroponic System ◽  
Aerial Parts ◽  
Chlorophylls A And B ◽  
Fluorescence Of Chlorophyll A ◽  
Inorganic Solutes

ASPECTOS BIOQUÍMICOS E FLUORESCÊNCIA DA CLOROFILA A EM PLANTAS DE MINIMELANCIA HIDROPÔNICA SOB ESTRESSE SALINO*     LAÍS MONIQUE GOMES DO Ó1, ALIDE MITSUE WATANABE COVA2, PETTERSON COSTA CONCEIÇÃO SILVA3, HANS RAJ GHEYI4, ANDRÉ DIAS DE AZEVEDO NETO5, ROGÉRIO FERREIRA RIBAS6   1Doutoranda em Engenharia Agrícola da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil [email protected]. 2Pós-Doutoranda no Programa de Pós-graduação de Engenharia Agrícola da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 3Doutor em Engenharia Agrícola, Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 4Professor Visitante, Universidade Federal do Recôncavo da Bahia, Cruz das Almas, Bahia, [email protected]. 5Professor Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 6Professor Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. *Este artigo é proveniente da tese de doutorado do primeiro autor.     1 RESUMO   A salinidade é um dos principais estresses abióticos que induz distúrbios bioquímicos e fisiológicos em diversas culturas. O objetivo do trabalho foi investigar os efeitos da salinidade da solução nutritiva (CEsol) sobre a produção, acúmulo de solutos orgânicos e inorgânicos e fluorescência da clorofila a em plantas de minimelancia cv. Sugar Baby. O delineamento experimental foi o inteiramente casualizado com quatro repetições. As plantas foram cultivadas em sistema hidropônico com cinco níveis de CEsol: 2,5; 3,5; 4,5; 5,5 e 6,5 dS m-1. Foram avaliados: massa do fruto, biomassa da parte aérea, teores de clorofilas a e b, fluorescência da clorofila a e teores de solutos orgânicos e inorgânicos. A massa do fruto e a biomassa seca da parte aérea foram influenciadas negativamente pela CEsol. Houve redução na concentração de carboidratos solúveis totais, aminoácidos livres, proteínas solúveis e prolina livre com o aumento da CEsol. Os íons sódio, cloreto e razão sódio/potássio aumentaram com a salinidade e os teores de potássio foram reduzidos. O incremento da salinidade aumentou linearmente o teor de clorofila b e reduziu linearmente o rendimento quântico da conversão de energia fotoquímica do FSII promovendo um ligeiro aumento no rendimento quântico da perda de energia regulada do FSII.   Palavras-chaves: biomassa, carboidratos, íons tóxicos, estresse abiótico.     Ó, L. M. G.; COVA, A. M. W.; SILVA, P. C. C.; GHEYI, H. R.; AZEVEDO NETO, A. D. de; RIBAS, R. F. BIOCHEMICAL ASPECTS AND CHLOROPHYLL A FLUORESCENCE IN HYDROPONIC MINI WATERMELON PLANTS UNDER SALT STRESS   2 ABSTRACT   Salinity is one of the main abiotic stresses that induce biochemical and physiological disorders in diverse crops. This study investigated the effects of nutrient solution salinity (ECsol) on production, accumulation of organic and inorganic solutes and chlorophyl a fluorescence in mini watermelon plants cv. Sugar Baby. The experimental design was completely randomized with four replications. The plants were grown in a hydroponic system with five levels of ECsol: 2.5; 3.5; 4.5; 5.5 and 6.5 dS m-1. The variables evaluated were the mass of the fruit, the biomass of the aerial parts, contents of chlorophylls a and b, fluorescence of chlorophyll a, and contents of organic and inorganic solutes. The mass of the fruit and dry biomass of the aerial parts was negatively influenced by ECsol. There was a reduction in the concentration of total soluble carbohydrates, free amino acids, soluble proteins and free proline with the increase in ECsol. The sodium, chloride and sodium/potassium ratio increased with ECsol and potassium levels were reduced. The increase in ECsol linearly increased the chlorophyll b content and reduced the quantum yield of the photochemical energy conversion of the PSII promoting a slight increase in the quantum yield of the regulated energy loss of the PSII.   Keywords: abiotic stress, biomass, carbohydrates, toxic ions.

Interactions between Photosynthetic Pigments Bound to Lipid and Protein Particles. Spectroscopic Properties

1979 ◽  
Vol 34 (7-8) ◽  
pp. 582-587
Author(s):  
Framçoise Techy ◽  
Monique Dinant ◽  
Jacques Aghion
Keyword(s):  
Chlorophyll A ◽  
Photosynthetic Pigments ◽  
Relative Concentration ◽  
Spectroscopic Properties ◽  
Chlorophyll B ◽  
Pheophytin A ◽  
Chlorophylls A And B ◽  
Protein Particles ◽  
Β Carotene

Abstract The spectroscopic (visible) properties of pigment-bearing lipid and protein particles extract­ ed from milk show that: 1) chlorophylls a and b bound to separate particles can form aggregates provided their relative concentration is high enough. Neither pheophytin a nor β-carotene, in the same conditions, form observable aggregates. 2) Chlorophylls a and b can co-aggregate when they are bound to the same particles. Pheophytin a as well as β-carotene seem to prevent the aggregation of chlorophyll a. β-carotene has no effect on the aggregation of chlorophyll b.

scholarly journals Study of chlorophylls and carotenoids in Sansevieria hyacinthoides leaves

2021 ◽  
pp. 62-65
Author(s):  
V. Velma ◽  
V. Kyslychenko ◽  
S. Velma ◽  
А. Popyk
Keyword(s):  
Chlorophyll A ◽  
Spectrophotometric Method ◽  
Biologically Active ◽  
Raw Material ◽  
Chlorophyll B ◽  
African Countries ◽  
Quantitative Content ◽  
Chlorophylls A And B ◽  
Chlorophyll A And B ◽  
Separation Results

Topicality. Sansevieria hyacinthoides (L.) Druce belongs to the Asparagaceae family. The plant is native to African countries. It has been introduced and naturalized in some countries of America, Asia, Australia and Europe. This species is grown as an ornamental plant in many countries, and as a medicinal plant in Africa. Aim. To determine the quantitative content of chlorophylls a and b and the amount of carotenoids in Sansevieria hyacinthoides leaves freshly collected and dried. Materials and methods. The quantitative content was determined by the spectrophotometric method. This method allows determining the amount of chlorophyll a and b and carotenoids by the characteristics of the absorption spectra without their prior separation. Results and discussion. The amount of chlorophyll a and b in the dried leaves was almost 7 times higher than in the freshly collected ones (1.82 ± 0.036 mg/g vs. 0.25 ± 0.005 mg/g, and 2.08 ± 0.038 mg/g vs. 0.29 ± 0.006 mg/g, respectively). The quantitative content of the amount of carotenoids differed by 3.6 times (0.05 ± 0.001 mg/g in freshly collected leaves, and 0.18 ± 0.004 mg/g in the dried raw material). Conclusions. The quantitative content of the amount of carotenoids, chlorophyll a and chlorophyll b in freshly collected and dried leaves of Sansevieria hyacinthoides has been determined by the spectrophotometric method. The dried plant raw material of Sansevieria leaves has a higher content of biologically active substances: chlorophyll a – 1.82 ± 0.036 mg/g, chlorophyll b – 2.08 ± 0.038 mg/g, and the amount of carotenoids – 0.18 ± 0.004 mg/g.

scholarly journals Assessment of the effect of heavy metal salts on the photosynthetic activity of aquatic plants

2021 ◽  
pp. 310-318
Author(s):  
G. V. Lobkova ◽  
E. I. Tikhomirova ◽  
Z. A. Simonova
Keyword(s):  
Chlorophyll A ◽  
Fluorescence Intensity ◽  
Aquatic Plants ◽  
Lemna Minor ◽  
Control Level ◽  
Lead Salt ◽  
Chlorophyll B ◽  
Chlorophylls A And B ◽  
Chlorophyll A And B ◽  
Effect Of Copper

The status of the photosynthetic pigments in the aquatic plants Lemna minor L. and Elodea canadensis Michx. under the action of Ni2+, Co2+, Cu2+ and Pb2+ acetate in concentrations 5.00, 2.50, 1.25, 0.62, 0.31, 0.15, 0.07, and 0.03 mg/L was assessed by changes in the fluorescence intensity of chlorophyll a and b and their ratio. It was established that nickel acetate in original solutions in all the above concentrations caused an increase in the fluorescence intensity of chlorophylls a and b in L. minor in relation to the control while the lead salt suppressed it. Co2+ acetate inhibits the fluorescence of chlorophyll a with concentrations in the initial solutions of 0.03 to 0.15 and 2.50 mg/L and that of chlorophyll b at all concentrations, except 0.62, 1.25 and 2.50 mg/L. For E. canadensis it was found that the salts of all metals at all concentrations caused a reduction of the fluorescence intensity of chlorophyll a relative to the control and increased it in the case of chlorophyll b. The exception is the effect of copper and lead acetates with a concentration of 1.25 mg/L, when the fluorescence intensity of chlorophyll b is maintained at the control level. The presence of Ni2+, Co2+, Cu2+, and Pb2+ acetates in all concentrations in the culture medium influences the quantitative and qualitative characteristics of chlorophyll a and b, which indicates a violation of the photosynthesis process. Our data on the change in the chlorophyll a / b ratio leads to a conclusion about degradation of chlorophyll a relative to chlorophyll b after the effect of heavy metals.

scholarly journals Non-destructive measurement of chlorophyll b:a ratios and identification of photosynthetic pathways in grasses by reflectance spectroscopy

2009 ◽  
Vol 36 (11) ◽  
pp. 857 ◽  
Author(s):  
Katharina Siebke ◽  
Marilyn C. Ball
Keyword(s):  
Chlorophyll A ◽  
Reflectance Spectra ◽  
Grass Species ◽  
Chlorophyll B ◽  
Hordeum Vulgare L ◽  
Chlorophylls A And B ◽  
Fluorescence Characteristics ◽  
Destructive Measurement ◽  
Non Destructive

Equations for non-destructive determination of chlorophyll b : a ratios in grasses were developed from reflectance spectra of intact leaves of barley (Hordeum vulgare L.) and two barley mutants: clorina f2, which lacks chlorophyll b and clorina f104, which has a low chlorophyll b content. These plants enabled separation of effects of chlorophyll composition on reflectance spectra due to differential light absorption by chlorophylls a and b and to measure the effects of chlorophyll b on the contribution of fluorescence emitted by chlorophyll a to the reflectance spectra. Indices developed from these data were then tested on growth chamber-grown leaves from six C3 and 17 C4 grass species (7 NAD-ME and 10 NADP-ME subtypes). We used the chlorophyll b : a ratio because the data were less skewed than the chlorophyll a : b ratio. The best index for determination of the chlorophyll b : a ratio utilised wavelengths affected by chlorophyll absorbance: [R626 – 0.5 (R603 + R647)]/[R552– R626]. The chlorophyll b : a ratio was significantly lower in the C4 than C3 grasses, but was not sufficient in itself to separate these two functional groups. However, because of differences in fluorescence characteristics, C3 and C4 species could be distinguished by an index based on wavelengths affected by chlorophyll fluorescence: [R696 to 709/R545 to 567].

scholarly journals Physiological responses of resistant and susceptible pepper plants to exogenous proline application under Phytophthora capsici stress

2022 ◽  
Vol 81 (1) ◽  
Author(s):  
Esra Koç
Keyword(s):  
Chlorophyll A ◽  
Phytophthora Capsici ◽  
Soluble Carbohydrates ◽  
Chlorophyll B ◽  
Antioxidant Power ◽  
The Third ◽  
Ferric Reducing Antioxidant Power ◽  
Dpph Scavenging Activity ◽  
Dpph Scavenging ◽  
Positive Effect

Phytophthora capsici Leon. is the main pathogen that limits the production of peppers. In this study, the effects of 1 and 10 mM proline (Pro), prior to exposure of resistant (CM-334) and susceptible (SD-8) pepper seedlings to P. capsici, on some physiological parameters were investigated. A lower Pro concentration (1 mM) was found to be more effective than 10 mM Pro in increasing the stress tolerance of the CM-334 cultivar. Namely, in CM-334 cultivar, the highest chlorophyll a, chlorophyll b, carotenoid, glucose and fructose content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity percentage were detected on the seventh day after application of 1 mM Pro + P. capsici, while the lowest malondialdehyde (MDA) amount was measured on the third day in the same treatment. The highest ferric reducing antioxidant power (FRAP) increase was determined on the seventh day in the 10 mM Pro + P. capsici application. The effects of the same Pro treatments on the SD-8 cultivar somewhat differed; the highest amounts of chlorophyll a, chlorophyll b, anthocyanins, fructose, total protein and endogenous Pro were detected on the seventh day in the 1 mM Pro + P. capsici application, while the lowest MDA amount was measured on the third day after the 10 mM Pro + P. capsici application, the highest DPPH % and FRAP values were detected on the seventh day with 10 mM Pro + P. capsici application. Although some differences were detected between the cultivars, Pro application against the P. capsici stress in general resulted in a positive effect on photosynthetic pigments, soluble carbohydrates and antioxidant capacity in pepper. The exogenous application of Pro helped the non-resistant cultivar to overcome the stress.

scholarly journals Influence of multicomponent contamination on the content of photosynthetic pigments in the leaves of woody plants commonly planted for greening of cities

2020 ◽  
Vol 28 (2) ◽  
pp. 203-208
Author(s):  
V. P. Bessonova ◽  
A. S. Chongova ◽  
A. V. Sklyarenko
Keyword(s):  
Chlorophyll A ◽  
Photosynthetic Pigments ◽  
Woody Plants ◽  
Robinia Pseudoacacia ◽  
Growing Season ◽  
Steppe Zone ◽  
Control Area ◽  
Chlorophyll B ◽  
Chlorophylls A And B ◽  
Platanus Orientalis

Woody plants, as an important element of optimization of the urban environment, respond negatively to the ever-increasing technogenic pressure in cities. Therefore, it is necessary to assess their vital status, the most sensitive indicator of which being the content of plastid pigments. In this article we analyze the effects of multicomponent contamination on quantitative fluctuation of the level of photosynthetic pigments in the leaves of woody plants and identify sensitive species for the purpose of phytoindication in order to assess the state the environment is currently in. For the purposes of our research we chose the most widespread tree species in the city of Dnipro (Steppe zone of Ukraine), growing in the area of intensive industrial pollution and high levels of emissions by vehicles. We determined the content of photosynthetic pigments (chlorophylls a and b, a + b, carotenoids) in the leaves of woody plants during different months of the growing season (June, July, August) and afterwards this data was used to compare the given parameters against the values taken from trees in the control area. The sum of chlorophyll levels a + b for the majority of plants was decreasing compared to the control. A more significant decrease in the content given by the sum of the a and b chlorophyll levels is observed in the assimilation organs of Aesculus hippocastanum L., Pinus pallasiana (D. Don) and Picea abies (L.) H. The most significant changes in the content of pigments in the leaves of plants under study were detected at the end of the growing season (in August). The content of green pigments in the leaves of Robinia pseudoacacia L., Platanus orientalis L. remains virtually unchanged. Under the influence of multicomponent contamination, the amount of pigments in the case of chlorophyll a in the majority of woody plant species decreases more rapidly compared to the control than in the case of chlorophyll b. The most noticeable drop in the content of chlorophyll a occurs in the leaves of Betula pendula Roth, Ae. hippocastanum, P. pallasiana, Acer platanoides L. and Tilia cordata Mill. The needles of P. abies and Picea pungens Engelm. 'Glauca’ on the contrary suffer from a significant reduction in the concentration of chlorophyll b. The species most resistant to multicomponent contamination in terms of changes in the content of chlorophyll in the leaf blade are R. pseudoacacia, P. orientalis. The concentration of carotenoids in the leaves of plants such as B. pendula, Ae. hippocastanum, A. platanoides, T. cordata, P. abies is lower than that of species growing in the relatively clean zone. The concentration of pigments in Populus alba L., P. pungens 'Glauca’ was higher during all of the months elapsed since the beginning of our study, whereas Ulmus laevis Pall., P. orientalis and R. pseudoacacia – had their concentrations reach an all time high in the second half of the growing season. Therefore, the peculiarities of quantitative fluctuation of photosynthetic pigments in plants, which are characterized by the variable resistance ability against the effects of technogenic multicomponent contamination, have been identified.

scholarly journals The Effect of Water Deficit and Nitrogen on the Antioxidant Enzymes’ Activity and Quantum Yield of Barley ( Hordeum vulgare L.)

2014 ◽  
Vol 42 (2) ◽  
pp. 398-404 ◽  
Author(s):  
Arezu MOVLUDI ◽  
Ali EBADI ◽  
Soodabeh JAHANBAKHSH ◽  
Mahdi DAVARI ◽  
Ghasem PARMOON
Keyword(s):  
Antioxidant Enzymes ◽  
Quantum Yield ◽  
Grain Yield ◽  
Water Deficit ◽  
Chlorophyll A ◽  
Proline Content ◽  
Carotenoid Content ◽  
Mild Stress ◽  
Chlorophyll B ◽  
Enzymes Activity

The effects of water deficit and nitrogen fertilizer were studied on antioxidant enzymes activity and quantum yield of barley. An experiment carried out in greenhouse in factorial subject based on a completely randomized design with three replications. Irrigation schedules imposed at three levels of 85%, 60% and 35% field capacity (FC), and nitrogen were applied in quantities of 40, 80 and 120 kg N ha-1. We determined Catalase (CAT), Peroxidase (POX) Polyphenol oxidase (PPO) activities, proline, chlorophyll and carotenoid content, quantum yield and grain yield. The results showed that severe stress (35% FC) increased the activities of CAT, POX and PPO enzymes and proline content, whereas the carotenoids, chlorophyll a and chlorophyll b decreased. Water deficiency caused the reduction in the quantum yield and the grain yield by 34%. Application of 80 kg of N during stress treatments resulted in higher enzyme activity and proline content. High amount of nitrogen reduced carotenoids, chlorophyll a, chlorophyll b, and in contrast, enhanced quantum yield. Application of 120 kg N ha-1 increased the yield up to 37% under mild stress (35% FC). Correlation coefficient and path coefficient showed that, grain yield was affected directly by amount of carotenoids and quantum yield.

scholarly journals RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO

2018 ◽  
Vol 31 (1) ◽  
pp. 9-18
Author(s):  
ALANA CRISTINA FERREIRA ARAÚJO ◽  
JOÃO CARLOS MADALÃO ◽  
ADRIANO JAKELAITIS ◽  
ALAN CARLOS COSTA ◽  
GABRIEL MARTINS ALMEIDA
Keyword(s):  
Quantum Yield ◽  
Chlorophyll A ◽  
Dry Matter ◽  
Additional Treatment ◽  
Photosynthetic Characteristics ◽  
Paspalum Notatum ◽  
Effective Quantum Yield ◽  
Chlorophyll B ◽  
Total Chlorophyll ◽  
Forage Species

ABSTRACT Some forages release allelopathic substances into the environment, and may prevent consortium with arboreal species in pastures. The objective of this work was to evaluate photosynthetic characteristics of pequizeiro plants (hereafter pequi) influenced by concentrations of residues of the forage species Urocholoa decumbens, Melinis minutiflora and Paspalum notatum. The treatments consisted of pequi cultivation under aerial residues of the three forage species mixed to the substrate in four concentrations (1, 2, 3 and 4% mass/mass), plus an additional treatment (comparative control) with pequi cultivated on the substrate without waste. The following parameters were evaluated: photosynthetic rate, stomatal conductance, transpiration rate, relationship between internal and external CO2 concentration (Ci/Ca), maximum quantum yield, effective quantum yield of FS II, electron transport rate, nonchemical quenching and chlorophyll index, concerning the content of chlorophyll a, b and total in pequi plants at 50 and 100 days after transplanting (DAT), and the relative production of dry matter at 100 DAT. At 50 DAT, the following photosynthetic variables were affected in pequi plants: A, gs, chlorophyll a, chlorophyll b and total chlorophyll when cultivated in the presence of forage residues. At 100 DAT, the following photosynthetic variables were affected in pequi plants: A, Fv/Fm, ETR, NPQ, chlorophyll a, chlorophyll b and total chlorophyll, when cultivated in the presence of forage residues. Pequi plants had reduced relative dry matter yield when grown in the presence of U. decumbens. This variable was also affected when pequi was grown in increasing concentrations of residues of the species U. decumbens, M. minutiflora and P. notatum.

scholarly journals Antioxidant Properties of Fruit and Vegetable Whey Beverages and Fruit and Vegetable Mousses

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3126
Author(s):  
Aleksandra Purkiewicz ◽  
Renata Pietrzak-Fiećko
Keyword(s):  
Antioxidant Activity ◽  
Chlorophyll A ◽  
Antioxidant Properties ◽  
Total Phenolic ◽  
Chlorophyll B ◽  
Fruit And Vegetable ◽  
Spectrophotometric Methods ◽  
Chlorophylls A And B ◽  
Whey Beverages ◽  
Β Carotene

The study assesses the antioxidant activity, total phenolic content, total flavonoids content and lipophilic pigments (β-carotene, chlorophyll a, chlorophyll b) content in homemade and marketed fruit and vegetable whey beverages and fruit and vegetable mousses. All of the tests were performed using spectrophotometric methods. The highest polyphenol content was found in the homemade green whey beverage W1G (541.95 mg/100 g) and the lowest in the market green whey beverage W2G (46.18 mg/100 g). In the fruit and vegetable mousses under study, the highest content of polyphenolic compounds was determined in the red mousse R3 (76.41 mg/100 g). The highest content of flavonoids was observed in the homemade orange whey beverage W1O (63.06 mg/100 g) and in the green mousse G2 (69.80 mg/100 g). The values of the antioxidant activity of whey beverages and mousses varied depending on the composition. The highest content of β-carotene was identified in homemade orange whey beverage (4.36 mg/100 g) and in orange mousses (in range 1.10–2.24 mg/100 g), while chlorophylls a and b—in homemade green whey beverage W1G (3.00 mg/100 g and 1.31 mg/100 g respectively) and in green mousses (chlorophyll a in range 0.54 to 1.42 mg/100 g and chlorophyll b in range 0.13 to 0.32 mg/100 g).

Analysis of Chlorophyll a in Sediments by High-Pressure Liquid Chromatography

1981 ◽  
Vol 38 (2) ◽  
pp. 205-214 ◽  
Author(s):  
Lewis M. Brown ◽  
Barry T. Hargrave ◽  
Michael D. MacKinnon
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Chlorophyll A ◽  
High Pressure Liquid Chromatography ◽  
Degradation Products ◽  
Direct Injection ◽  
Reversed Phase ◽  
Solvent Mixtures ◽  
Chlorophyll B ◽  
Chlorophylls A And B

We have developed a method that uses high-pressure liquid chromatography (HPLC) with fluorometric detector for the determination of concentrations of chlorophylls a and b and their pheophytins in sediments. A reversed-phase column allowed direct injection of extracts prepared in the conventional manner (90% acetone or other solvent mixtures containing water). Concentrations of chlorophyll a in acetone estimated by a spectrophotometric method (using the acidification ratio) agreed with those estimated by HPLC. Chlorophyll a concentrations in sediments estimated by fluorometry were sometimes quite different from those estimated by HPLC or spectrophotometry. Estimates of concentrations of chlorophyll b and pheophytins a and b can be made by the HPLC method even in the presence of degradation products other than pheophytins that would interfere with the determination by spectrophotometry or fluorometry. The method is sensitive, rapid (14 min per sample), probably compatible with a variety of solvent mixtures, and can be automated for processing large numbers of samples.Key words: chlorophyll a, chlorophyll b, pheophytins, high-pressure liquid chromatography, sediments, algae, epipelic, biomass, primary productivity, suspended particulate matter

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