Quantification Of Chlorophyll Research Articles

Evaluation of the Effect of Growth Factors on Chlorophylls a and b Production from Microalgae.

Microalgae contain two main groups of pigments: chlorophylls and carotenoids. Chlorophyll is a green pigment that absorbs light energy and transforms it into chemical energy to facilitate the synthesis of organic compounds. This pigment serves as a valuable primary source for biotechnological input products in the food, pharmaceutical, and cosmetic industries due to its high antioxidant properties and coloring capabilities. The objective of this research was to evaluate the effect of growth factors (CO2 concentration, light color, and light intensity) through a Taguchi L4 experimental design on cell growth and the cellular content of chlorophyll a and b in Chlorella sorokiniana, followed by validation of the method using Haematococcus pluvialis microalgae as an additional study model. Cell growth was quantified using the optical density spectrophotometric technique at a wavelength of 550 nm. For the quantification of chlorophylls, a cell extract was obtained using a 90% pure acetone solution, and subsequently, the concentrations of chlorophylls a and b were quantified using spectrophotometric techniques at wavelengths of 647 nm and 664 nm, according to the method described by Jeffrey and Humphrey. The experimental results indicated that controlling conditions of low CO2 addition, purple light, and low light intensity increases both cell growth and the concentration of chlorophylls a and b within the cells. The implementation of this chlorophyll quantification method allows for quick, simple, and precise determination of chlorophyll content, as the wavelengths used are at the absorbance peaks of both types of chlorophylls, making this technique easily reproducible for any microalgae under study.

Predictive modelling of chlorophyll in Mombaça grass leaves by hyperspectral reflectance data and machine learning

AbstractChlorophyll (Chl) concentration is one of the factors that affects crop productivity. This study investigated the prediction of chlorophyll concentrations in Mombaça grass' leaves using hyperspectral data and machine learning techniques. Chlorophyll variations were induced by different levels of nitrogen fertilization (104, 208, 312, and 416 kg ha−1). Spectral signatures (400–2500 nm) and chlorophyll contents of the leaves were obtained in October, November, and December 2017, and January 2018. Models were generated using Partial Least Square Regression (PLSR), Random Forest (RF), and Support Vector Regression (SVR). Two validation techniques were employed: holdout, dividing the data into training (75%) and testing (25%) sets; and leave‐one‐date‐out cross‐validation (LOOCV), in which one date was omitted during model training and used to predict the omitted date's value. Chlorophyll concentrations varied according to N doses, with the highest concentrations observed in October and December. In these months, there were greater variations in spectral reflectance in the green and red bands (530–680 nm). December was identified as the ideal period for chlorophyll quantification, for both holdout and LOOCV validation techniques. The SVR technique performed best (R2 = 0.71, RMSE = 0.23 mg g−1, dr = 0.72) compared to RF (R2 = 0.63, RMSE = 0.27 mg g−1, dr = 0.66) and PLSR (R2 = 0.60, RMSE = 0.27 mg g−1, dr = 0.67). Therefore, the prediction of chlorophyll in Mombaça grass using spectroradiometry is promising and applicable across different cultivation periods.

Enhanced quantification of chlorophyll a and its degradation products in olive oil using time-resolved laser-induced fluorescence fingerprint analysis

AbstractPotential errors in the fluorescence analysis of chlorophylls and their degradation products, primarily due to spectral overlap and inner filter, are widely acknowledged. This study aimed to devise a sensitivity-enhanced technique for the concurrent quantification of chlorophyll a and its degradation products while minimizing effects from type-B chlorophylls. Initially, a time-resolved laser-induced fluorescence spectroscopic system was designed and tested on stardard chlorophyll samples. The origins, implications, and mitigation strategies of spectral overlap and the inner filter effect on the measured fluorescence intensity were thoroughly examined. Then, this methodology was proved to be efficacious within complex liquid matrices derived from olive oil. The experimental outcomes not only shed additional light on the mechanisms of chlorophyll fluorescence overlap and the inner filter effect, but also establish a general framework for developing spectrally and timely resolved fluorescence fingerprint analysis for the simultaneous quantification of chlorophylls and their degradation products at high concentrations.

Induction of volatile organic compounds in chrysanthemum plants following infection by Rhizoctonia solani.

This study investigated the effects of Rhizoctonia solani J.G. Kühn infestation on the volatile organic compound (VOC) emissions and biochemical composition of ten cultivars of chrysanthemum (Chrysanthemum × morifolium /Ramat./ Hemsl.) to bring new insights for future disease management strategies and the development of resistant chrysanthemum cultivars. The chrysanthemum plants were propagated vegetatively and cultivated in a greenhouse under semi-controlled conditions. VOCs emitted by the plants were collected using a specialized system and analyzed by gas chromatography/mass spectrometry. Biochemical analyses of the leaves were performed, including the extraction and quantification of chlorophylls, carotenoids, and phenolic compounds. The emission of VOCs varied among the cultivars, with some cultivars producing a wider range of VOCs compared to others. The analysis of the VOC emissions from control plants revealed differences in both their quality and quantity among the tested cultivars. R. solani infection influenced the VOC emissions, with different cultivars exhibiting varying responses to the infection. Statistical analyses confirmed the significant effects of cultivar, collection time, and their interaction on the VOCs. Correlation analyses revealed positive relationships between certain pairs of VOCs. The results show significant differences in the biochemical composition among the cultivars, with variations in chlorophyll, carotenoids, and phenolic compounds content. Interestingly, R. solani soil and leaf infestation decreased the content of carotenoids in chrysanthemums. Plants subjected to soil infestation were characterized with the highest content of phenolics. This study unveils alterations in the volatile and biochemical responses of chrysanthemum plants to R. solani infestation, which can contribute to the development of strategies for disease management and the improvement of chrysanthemum cultivars with enhanced resistance to R. solani.

Ecotoxicological effects of ketoprofen and fluoxetine and their mixture in an aquatic microcosm

The effects of fluoxetine (antidepressant) and ketoprofen (analgesic) on aquatic ecosystems are largely unknown, particularly as a mixture. This work aimed at determining the effect of sublethal concentrations of both compounds individually (0.050 mg/L) and their mixture (0.025 mg/L each) on aquatic communities at a microcosm scale for a period of 14 d. Several physicochemical parameters were monitored to estimate functional alterations in the ecosystem, while model organisms (Daphnia magna, Lemna sp., Raphidocelis subcapitata) and the sequencing of 16S/18S rRNA genes permitted to determine effects on specific populations and changes in community composition, respectively. Disturbances were more clearly observed after 14 d, and overall, the microcosms containing fluoxetine (alone or in combination with ketoprofen) produced larger alterations on most physicochemical and biological variables, compared to the microcosm containing only ketoprofen, which suffered less severe changes. Differences in nitrogen species suggest alterations in the N-cycle due to the presence of fluoxetine; similarly, all pharmaceutical-containing systems decreased the brood rate of D. magna, while individual compounds inhibited the growth of Lemna sp. No clear trends were observed regarding R. subcapitata, as indirectly determined by chlorophyll quantification. The structure of micro-eukaryotic communities was altered in the fluoxetine-containing systems, whereas the structure of bacterial communities was affected to a greater extent by the mixture. The disruptions to the equilibrium of the microcosm demonstrate the ecological risk these compounds pose to aquatic ecosystems.

Optimal-Band Analysis for Chlorophyll Quantification in Rice Leaves Using a Custom Hyperspectral Imaging System.

Hyperspectral imaging (HSI) is a promising tool in chlorophyll quantification, providing a non-invasive method to collect important information for effective crop management. HSI contributes to food security solutions by optimising crop yields. In this study, we presented a custom HSI system specifically designed to provide a quantitative analysis of leaf chlorophyll content (LCC). To ensure precise estimation, significant wavelengths were identified using optimal-band analysis. Our research was centred on two sets of 120 leaf samples sourced from Thailand's unique Chaew Khing rice variant. The samples were subjected to (i) an analytical LCC assessment and (ii) HSI imaging for spectral reflectance data capture. A linear regression comparison of these datasets revealed that the green (575 ± 2 nm) and near-infrared (788 ± 2 nm) bands were the most outstanding performers. Notably, the green normalised difference vegetation index (GNDVI) was the most reliable during cross-validation (R2=0.78 and RMSE = 2.4 µg∙cm-2), outperforming other examined vegetable indices (VIs), such as the simple ratio (RED/GREEN) and the chlorophyll index. The potential development of a streamlined sensor dependent only on these two wavelengths is a significant outcome of identifying these two optimal bands. This innovation can be seamlessly integrated into farming landscapes or attached to UAVs, allowing real-time monitoring and rapid, targeted N management interventions.

PHYSIOLOGICAL AND BIOCHEMICAL BIOMARKERS OF MACROPHYTE RESILIENCE TO MILITARY-RELATED TOXIC STRESSORS

This study employs state-of-the-art analytical tools to investigate the ecotoxicological impacts of mercury contamination on aquatic macrophytes in post-military zones, focusing on Typha latifolia and Lemna minor as model organisms. The research methodology integrates multiple analytical techniques: spectrophotometric chlorophyll quantification using the Holm-Wettstein method, atomic absorption spectrometry utilizing a C-115PK Selmi spectrometer (precision ±0.001 mg/L), and fluorescence analysis via Flyuorat-02-Panorama spectrofluorometer. Through this comprehensive analytical approach, we elucidated the bioaccumulation patterns and physiological responses of these hydrophytes to varying concentrations of mercury (0.35-2.0 mg/L). Results demonstrated differential bioaccumulation capacities between T. latifolia and L. minor, with the latter exhibiting higher mercury sequestration potential (0.51 mg/kg vs 0.4 mg/kg dry weight). Concentration-dependent phytotoxic effects were observed, manifesting as morphological alterations, chlorophyll degradation, and disruption of photosynthetic processes. Notably, a consistent increase in the chlorophyll b to chlorophyll a ratio was documented, indicative of selective degradation of photosystem II under mercury stress. The study further revealed the inactivation of key Calvin cycle enzymes, leading to attenuated carbon fixation and overall photosynthetic capacity. These findings not only elucidate the mechanistic underpinnings of mercury toxicity in aquatic macrophytes but also underscore their potential as bioremediators in mercury-contaminated aquatic ecosystems. The research provides critical insights for developing targeted phytoremediation strategies and ecosystem restoration protocols in post-military aquatic environments.

A new index for the rapid generation of chlorophyll time series from hyperspectral imaging of sediment cores

AbstractTime series analyses of pigment concentrations are key to understanding past aquatic ecosystem dynamics. As lake sediments provide a window into longer‐term changes, innovative paleolimnological chlorophyll quantification could provide impactful insights into past environmental processes. Lab‐based hyperspectral imaging of sediment cores is an emerging technique to develop rapid, non‐destructive, high‐resolution chlorophyll inferences but it requires more extensive vetting. Despite recent advances in model development, there is still a knowledge gap about the reliability of chlorophyll models when applied in lakes with diverse properties, as well as the potential confounding effects of physical sediment properties on these models. We assessed the performance of 23 chlorophyll indices based on paired measurements collected via hyperspectral imaging and spectrophotometry for 202 samples spread across seven Canadian lake sediment cores. The best performance was by a new index based on the wavelength of the red‐edge minimum point (λREMP). We tested the applicability of λREMP to a broad range of sediment cores using a database of 116 cores, and found the index to provide reliable reconstructions of ƩChl (i.e., chlorophyll a and b and their degradation products) trends in 84% of sites. Further analyses indicated that sediment characteristics including particle size, organic matter content, water content, and density had no systematic impact on ƩChl, but greater sediment brightness did increase ƩChl inferences from hyperspectral images. Hyperspectral core scanning is poised to facilitate the generation of high‐resolution chlorophyll time series data, which could greatly improve our understanding of trajectories of change from the local to global scales.

Miniaturized Vis–NIR handheld spectrometer for non-invasive pigment quantification in agritech applications

Advanced precision agriculture requires the objective measurement of the structural and functional properties of plants. Biochemical profiles in leaves can differ depending on plant growing conditions. By quantitatively detecting these changes, farm production processes can be optimized to achieve high-yield, high-quality, and nutrient dense agricultural products. To enable the rapid and non-destructive detection on site, this study demonstrates the development of a new custom-designed portable handheld Vis–NIR spectrometer that collects leaf reflectance spectra, wirelessly transfers the spectral data through Bluetooth, and provides both raw spectral data and processed information. The spectrometer has two preprogramed methods: anthocyanin and chlorophyll quantification. Anthocyanin content of red and green lettuce estimated with the new spectrometer showed an excellent correlation coefficient of 0.84 with those determined by a destructive gold standard biochemical method. The differences in chlorophyll content were measured using leaf senescence as a case study. Chlorophyll Index calculated with the handheld spectrometer gradually decreased with leaf age as chlorophyll degrades during the process of senescence. The estimated chlorophyll values were highly correlated with those obtained from a commercial fluorescence-based chlorophyll meter with a correlation coefficient of 0.77. The developed portable handheld Vis–NIR spectrometer could be a simple, cost-effective, and easy to operate tool that can be used to non-invasively monitor plant pigment and nutrient content efficiently.

Evaluation of Hybrid Models for Maize Chlorophyll Retrieval Using Medium- and High-Spatial-Resolution Satellite Images

Accurate estimation of the leaf or canopy chlorophyll content is crucial for monitoring crop growth conditions. Remote sensing monitoring of crop chlorophyll is a non-destructive, large-area, and real-time method that requires reliable retrieval models and satellite data. High-resolution satellite imagery generally has better object recognition capabilities. However, the influence of the spectral and spatial resolution of medium- and high-spatial-resolution satellite imagery on chlorophyll retrieval is currently unexplored, especially in conjunction with radiative transfer models (RTMs). This has important implications for the accurate quantification of crop chlorophyll over large areas. Therefore, the objectives of this study were to establish an RTM for the retrieval of maize chlorophyll and to compare the chlorophyll retrieval capability of the model using medium- and high-spatial-resolution satellite images. We constructed a hybrid model consisting of the PROSAIL model and the Gaussian process regression (GPR) algorithm to retrieve maize leaf and canopy chlorophyll contents (LCC and CCC). In addition, an active learning (AL) strategy was incorporated into the hybrid model to enhance the model’s accuracy and efficiency. Sentinel-2 imagery with a spatial resolution of 10 m and 3 m-resolution Planet imagery were utilized for the LCC and CCC retrieval, respectively, using the hybrid model. The accuracy of the model was verified using field-measured maize chlorophyll data obtained in Dajianchang Town, Wuqing District, Tianjin City, in 2018. The results showed that the AL strategy increased the accuracy of the chlorophyll retrieval. The hybrid model for LCC retrieval with 10-band Sentinel-2 without AL had an R2 of 0.567 and an RMSE of 5.598, and the model with AL had an R2 of 0.743 and an RMSE of 3.964. Incorporating the AL strategy improved the model performance (R2 = 0.743 and RMSE = 3.964). The Planet imagery provided better results for chlorophyll retrieval than 4-band Sentinel-2 imagery but worse performance than 10-band Sentinel-2 imagery. Additionally, we tested the model using maize chlorophyll data obtained from Youyi Farm in Heilongjiang Province in 2021 to evaluate the model’s robustness and scalability. The test results showed that the hybrid model used with 10-band Sentinel-2 images achieved good accuracy in the Youyi Farm area (LCC: R2 = 0.792, RMSE = 2.8; CCC: R2 = 0.726, RMSE = 0.152). The optimal hybrid model was applied to images from distinct periods to map the spatiotemporal distribution of the chlorophyll content. The uncertainties in the chlorophyll content retrieval results from different periods were relatively low, demonstrating that the model had good temporal scalability. Our research results can provide support for the precise management of maize growth.

Monitoring chlorophyll changes during Tencha processing using portable near-infrared spectroscopy

Monitoring chlorophyll during Tencha (the raw ingredient for matcha) processing is critical for determining the matcha's color and quality. The purpose of this study is to explore the mechanism of chlorophyll changes during Tencha processing and evaluate the viability of predicting its content by a portable near-infrared (NIR) spectrometer. The Tencha samples' spectral data were first preprocessed using various preprocessing techniques. Subsequently, iteratively variable subset optimization (IVSO), bootstrapping soft shrinkage (BOSS), and competitive adaptive reweighted sampling (CARS) were used to optimize and build partial least square (PLS) models. The CARS-PLS models achieved the best predictive accuracy, with correlation coefficients of prediction (Rp) = 0.9204 for chlorophyll a, Rp = 0.9282 for chlorophyll b, and Rp = 0.9385 for total chlorophyll. These findings suggest that NIR spectroscopy could be used as a surrogate for immediate quantification and monitoring of chlorophyll during Tencha processing.

Studies on physiological and productive effects of multi-leader training systems and Prohexadione-Ca applications on apple cultivar 'WA 38′

The release of new apple varieties able to improve consumer satisfaction provides the opportunity to modernize orchards and transition them away from unlucrative plantings towards highly productive, high-value cultivation systems. Top-working an existing, unprofitable mature orchard by grafting a new variety allows the orchardist to take advantage of an existing root system to achieve early bearing and reduce the establishment cost. Often, the scion in a new top-grafted orchard can present excessive vigor in the years following the grafting due to the abundance of reserves stored in the mature root system that become available for the new variety at the beginning of the season. This case study focuses on ‘WA 38′, an apple variety released in 2017 to Washington State growers. ‘WA 38′ can show variable vigor levels depending on the choice of rootstock, training system, planting density, pruning technique, water availability, and soil characteristics. Prohexadione-calcium (Pro-Ca, Apogee®) has been utilized for years in apple and other crops as a growth regulator with inhibitory activity on gibberellin synthesis, with the common effect of reducing shoot growth and canopy development and other potential physiological effects depending on genetics of the variety, timing, and rate of applications. This study investigated the physiological responses of ‘WA 38′ scion top-grafted on an 8-year-old Granny Smith/M.9 orchard and then trained to 1, 2, and 3-axis systems—suitable for modern mid-high-density planting—with and without the application of Pro-Ca for two consecutive years. The growth regulator was applied in post-bloom at a 250 ppm rate, starting at approximately 12-cm shoot length for three sprays per season. The parameters assessed to evaluate the impact of Pro-Ca on the variety in three training systems were: one-year-shoot length, internode length, dormant pruning weights, number of flower clusters per tree, photosynthetic carbon assimilation rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, chlorophyll determination (by SPAD and chemical extraction), leaf mineral analysis (macro and micro-nutrients), yield per tree, fruit size distribution and packout. The present results confirmed the effectiveness of the Pro-Ca in reducing the canopy growth and vigor in ‘WA 38′, with diminished internode length, total shoot length, and lower amount of pruned material. Leaf gas exchange parameters and chlorophyll quantification highlighted an alteration of tree physiology by Pro-Ca application with increased transpiration, stomatal conductance, intercellular CO2 concentration, and higher concentrations of chlorophyll a and b with respect to untreated trees. Pro-Ca-treated- ‘WA 38′ trees did not show any negative effect on productivity; rather, an increased average fruit mass and an enhanced proportion of apples in the extra-large size category compared to control. Fewer significant differences were found in the comparison between the training systems. Overall, the 3-axis system showed a higher yield and greater number of flower clusters per tree with a lower average area of each leader in comparison to 1-axis. Further investigations will shed light on ‘WA 38′ tree performance, productivity, and fruit quality after multiple years of Pro-Ca treatment to offer orchard management recommendations for a modern, top-worked, machine-friendly orchard.

XÂY DỰNG VÀ TRIỂN KHAI ĐÁNH GIÁ BÀI THÍ NGHIỆM ẢO “ĐỊNH LƯỢNG CHLOROPHYLL BẰNG PHƯƠNG PHÁP QUANG PHỔ” TẠI TRƯỜNG ĐẠI HỌC NHA TRANG

The study focuses on the development, implementation, and evaluation of the use of the virtual biology experiment of "Quantification of chlorophyll by spectroscopy" compared with the traditional educational method (hands-on laboratory labs, which involves physical presence, procurement of equipment, specific materials, and procedures). 2D and 3D models of equipment in the lesson were designed based on graphic tools (Blender, Adobe Illustrator). The movements, manipulation and troubleshooting of the virtual experiment (VE) are simulated using the Unity engine. The web-based VE was developed and evaluated the impact of VE by comparing a group of deployed students (Group 1) with a group of non-implemented students (Group 2). The results of implementation in students show that Group 1 had higher average test scores in understanding the concepts, definitions, steps of the experiment, and notes on using laboratory equipment compared to Group 2 (p<0.05). The students in Group 1 were also more confident in performing skills in scientific procedures as well as the ability to acquire knowledge in the laboratory was higher than in Group 2 (p<0.05). The students in Group 1 highly appreciated the criteria of the benefits of VE in memorizing concepts, steps of the experiment, and helping to recognize common mistakes during the experiment (p<0, 05). However, VE still cannot replace the "real" biology experiment in improving learners' manipulation skills. Research results showed that VE can become a powerful tool to cooperate with traditional educational methods in training students in biological laboratory skills.

An evaluation of a spectral fluorometer for monitoring chlorophyll a in New York State lakes

Prestigiacomo AR, June SG, Gorney RM, Smith AJ, Clinkhammer AC. 2022. An evaluation of a spectral fluorometer for monitoring chlorophyll a in New York State lakes. Lake Reserv Manage. 38:318–333. The quantification of chlorophyll a in surface waters through sampling and laboratory extraction methods has limitations, including the lack of phytoplankton composition analysis and delayed analysis time. Recently, automated instruments have been developed to quickly provide estimation of total chlorophyll a and characterize phytoplankton composition into functional groups. Here, we analyzed a dataset of paired, laboratory-extracted chlorophyll a samples (Chl-a) and chlorophyll a estimated from a spectrofluorometer (FluoroProbe, bbe Moldaenke; FPChl-a) for comparability at several time scales. We found that FPChl-a was highly correlated to Chl-a (r > 0.8) but overestimated Chl-a by 1.5–2 times on average. Summer average FPChl-a was higher than summer average Chl-a, resulting in incorrect lake evaluations against selected thresholds. Linear least squares regression of Chl-a/FPChl-a was highly significant (P < 0.01) and demonstrated a good fit (r2 > 0.75) but had high variability, consistent with FPChl-a performance values reported in the scientific literature. Factors such as FPChl-a magnitude and algal dominance were statistically important factors affecting the Chl-a/FPChl-a relationship. We developed a multiple linear regression method for postcalibrating FPChl-a to equivalent Chl-a values (adjusted FPChl-a) and applied it to the FPChl-a dataset. Adjusted FPChl-a values were unbiased and compared well with Chl-a (mean residual equal to 0 µg/L). Adjusted FPChl-a summer averages resulted in correct waterbody evaluation in more than 90% of lakes. We propose that the FluoroProbe, properly postcalibrated to adjusted FPChl-a, can be used as a surrogate of Chl-a in open water monitoring applications, reducing the need for traditional laboratory Chl-a samples for lake monitoring and management.

Bioherbicide Effect of Effluent from Processed Manihot esculentus Tubers

Effluents from processed bitter cassava (Manihot esculentus) tubers as bioherbicide was applied on the leaves of Beans, Broom weed, Maize, and Itch grass and investigated. Quantitative and qualitative characterization of microorganisms (bacteria and fungi) was done both in effluent and test soil. Mineral analysis using atomic absorption spectrum (AAS), cyanide quantification in the effluent, and quantification of chlorophyll (a and b) from the leaves of test plants (Beans, Broom weed, Maize, and Itch grass) were carried out. The result from the microbial characterization of effluent, test soil, and control soil revealed the effluent had the highest microbial load. The isolated bacteria were Staphylococcus spp, Bacillus spp, Lactobacillus, and E. coli. Test soil had 16.13% Staphylococcus, 9.68% Bacillus spp, 16.13% Lactobacillus, and 6.45% E. coli. The isolated fungi were Saccharomyces, Mucor, and Aspergillus in the effluent, while Saccharomyces and Mucor were in the test soil and only Aspergillus in the control soil.The fungal count revealed a high total viable count (TVC) in the effluent (7.0×104 cfu/ml) followed by test soil (6.6×104 cfu/ml) while control soil had the least (4.5%×104 cfu/ml). Cyanide analysis of effluent revealed 1.0 mg/ml, while metal analysis revealed potassium (40.221 mg/kg), sodium (32.009 mg/kg), Manganese (0.057 mg/kg) and Copper (-0.004mg/kg).The chlorophyll(a and b) concentration expressed in µg/mlof the experimented plants (Beans, Broom weed, Maize, and Itchgrass) further revealed a significant (p≤0.05) decrease concerning the volume of effluent applied (50 ml and 25 ml).Dicotyledonous plants; beans (0.461 + 0.025 and 0.609 + 0.013chlorophyll (a) compared to a control of 7.698+ 0.100.Chlorophyll(b) on the other hand revealed 5.507 + 0.141and 11.599 + 0.282 when compared with control of 16.426 + 0.016). Broom weed (0.291 + 0.071 and 0.457 + 0.068 for chlorophyll (a) when compared to the control with 0.595 + 0.071 and 1.549+0.141 and 1.683+0.353 for chlorophyll(b) when compared to the control with 22.252 + 0.282. Other plants analyzed revealed various significant (p≤0.05) decreased levels of chlorophyll (a and b). All the results revealed this effluent may be selectively used as a potential bioherbicide especially when applied to the leaves.

Geographical discrimination of grapevine leaves using fibre optic fluorescence data and chemometrics. Determination of total polyphenols and chlorophylls along different vegetative stages

Auto fluorescence of grapevine leaves has been employed to discriminate vineyards from two different geographical regions and to quantify the amount of total polyphenols and chlorophylls. For that, fluorescence spectroscopy with an optical fibre was used on samples of grapevine leaves (previously freeze-dried) and excitation-emission matrices were collected. Two spectral regions were analysed independently: one with excitation wavelengths from 279 to 372 nm and emission wavelengths from 384 to 496 nm, and the second with excitation between 390 and 585 nm and the emission between 654 and 756 nm. Firstly, an exploratory analysis was performed with parallel factor analysis (PARAFAC) to extract useful information from the data (scores and loadings). The obtained scores were used to perform a linear discriminant analysis (LDA) model for the classification of samples according to its geographical region. A total of 95% of correct predictions were obtained in the validation samples. Moreover, the PARAFAC scores of the components used in each model were analysed along the vegetative stage and a clear evolution with time has been observed.The quantification of total polyphenols and chlorophylls was also carried out with unfolded partial least squares (U-PLS) and N-way partial least squares (N-PLS). Good correlation coefficients (for the validation set) were obtained for both parameters and similar results were achieved with both algorithms (0.82 (U-PLS) and 0.76 (N-PLS) for total polyphenol and 0.83 (U-PLS) and 0.82 (N-PLS) for total chlorophylls).

ZmbHLH121, a maize bHLH transcription factor inducing leaf senescence by accelerating ROS accumulation in maize (Zea mays L.)

Leaf senescence is the final stage of leaf development which is induced by many genetic and environmental factors. To reveal the role of transcription factors in leaf senescence, we studied the function of a bHLH transcription factor ZmbHLH121 in maize. The overexpression of ZmbHLH121 exhibited phenotypes with leaf senescence. Higher expression pattern of ZmbHLH121 was observed in the immature leaves through expression analysis at early vegetative developmental stages. Results of 3,3-diaminobenzidine (DAB), nitroblue tetrazolium chloride (NBT) histochemical analysis, quantitative measurement of reactive oxygen species (ROS), chlorophyll quantification and transcriptome analysis revealed that, ZmbHLH121 positively regulated leaf senescence by accelerating ROS production and chlorophyll breakdown in maize leaves. It is suggested that, ZmbHLH121 regulated leaf senescence might be due to the excess amount of ROS production and chlorophyll loss in leaves. This study provided useful clue about the mechanism of ZmbHLH121 mediated leaf senescence.

Extraction and Quantification of Chlorophylls, Carotenoids, Phenolic Compounds, and Vitamins from Halophyte Biomasses

Halophytes are salt-tolerant plants, and they have been utilised as healthy, nutritious vegetables and medicinal herbs. Various studies have shown halophytes to be rich in health-beneficial compounds with antioxidant activity, anti-inflammatory and antimicrobial effects, and cytotoxic properties. Despite their potential, these plants are still underutilised in agriculture and industrial applications. This review includes the state-of-the-art literature concerning the contents of proanthocyanidins (also known as condensed tannins), total phenolic compounds, photosynthetic pigments (chlorophyll and carotenoids), and vitamins in various halophyte biomasses. Various extraction and analytical methods are also considered. The study shows that various species have exhibited potential for use not only as novel food products but also in the production of nutraceuticals and as ingredients for cosmetics and pharmaceuticals.

Growth kinetics and quantification of carbohydrate, protein, lipids, and chlorophyll of Spirulina platensis under aqueous conditions using different carbon and nitrogen sources

This study evaluated different carbon and nitrogen sources on the growth and production of carbohydrates, protein, lipids, and chlorophyll of Spirulina platensis LEB-52 through an easy successive methodology under aqueous conditions. Spirulina platensis was cultivated at 120 rpm and light intensity of 156 µmol m−2 s−1 in a 500 mL Erlenmeyer flask with a working volume of 250 mL, using Zarrouk’s medium. The biomass, carbohydrate, and protein production together with the specific growth rate did not show a significant difference between NaHCO3 and Na2CO3. The salts of urea and ammonium are not an alternative nitrogen sources of low cost for Spirulina platensis cultivation. From the experimental results obtained in this study, a successful estimate of carbohydrate, protein, lipids, and chlorophyll content inside Spirulina platensis was achieved without use advanced analytical techniques, allowing saves resources and time. This method can be extrapolated to other microorganisms and cultivation regimens.

Water quality in natural protected areas in Cancun, Mexico: A historic perspective for decision makers

Economic activities carried out in coastal zones have brought about changes in them. One of the most evident and harmful is eutrophication. In the northern zone of the Mexican Caribbean, the city of Cancun is a major hub for tourism activities and many of them are carried out in natural protected areas, which are particularly vulnerable owing to the proximity of urban areas. In this research, we measured the physicochemical parameters of water in two climatic seasons, and compared them in perspective (2006–2019) in order to identify changes over time. Four polygons in two natural protected areas were studied, differences according to their physicochemical parameters were identified by means of spatial and temporary comparisons. We compared our results with data from previous years and found an increasing trend in nutrients concentration and high variability in the quantification of silicates and chlorophyll a. Cadmium was found at concentrations over recommended levels for protecting aquatic life. Critical and vulnerable points of this Caribbean coastal zone are identified. In addition to complying with the analyses required by national regulations, it is proposed to choose N, P and chlorophyll as the parameters permanently measured by entities with multi-annual budgets. This sort of analysis will enable better decision-making, creating and modifying plans and actions for the management and conservation of the Greater Caribbean.