Significant Differences In Chlorophyll Research Articles

Combined toxic effects of polystyrene nanoplastics and lead on Chlorella vulgaris growth, membrane lipid peroxidation, antioxidant capacity, and morphological alterations.

In recent years, there has been a significant rise in the utilization of amino-functionalized polystyrene nanoplastics (PS-NH2). This surge in usage can be attributed to their exceptional characteristics, including a substantial specific surface area, high energy, and strong reactivity. These properties make them highly suitable for a wide range of industrial and medical applications. Nevertheless, there is a growing apprehension regarding their potential toxicity to aquatic organisms, particularly when considering the potential impact of heavy metals like lead (Pb) on the toxicity of PS-NH2. Herein, we examined the toxic effects of sole PS-NH2 (90nm) at five concentrations (e.g., 0, 0.125, 0.25, 0.5, and 1mg/L), as well as the simultaneous exposure of PS-NH2 and Pb2+ (using two environmental concentrations, e.g., 20μg/L for Pb low (PbL) and 80μg/L for Pb higher (PbH)) to the microalga Chlorella vulgaris. After a 96-h exposure, significant differences in chlorophyll a content and algal growth (biomass) were observed between the control group and other treatments (ANOVA, p < 0.05). The algae exposed to PS-NH2, PS-NH2 + PbL, and PS-NH2 + PbH treatment groups exhibited dose-dependent toxicity responses to chlorophyll a content and biomass. According to the Abbott toxicity model, the combined toxicity of treatment groups of PS-NH2 and PbL,H showed synergistic effects. The largest morphological changes such as C. vulgaris' size reduction and cellular aggregation were evident in the medium treated with elevated concentrations of both PS-NH2 and Pb2+. The toxicity of the treatment groups followed the sequence PS-NH2 < PS-NH2 + PbL < PS-NH2 + PbH. These results contribute novel insights into co-exposure toxicity to PS-NH2 and Pb2+ in algae communities.

Pigment Diversity in Leaves of Caladium × hortulanum Birdsey and Transcriptomic and Metabolic Comparisons between Red and White Leaves.

Leaf color is a key ornamental characteristic of cultivated caladium (Caladium × hortulanum Birdsey), a plant with diverse leaf colors. However, the genetic improvement of leaf color in cultivated caladium is hindered by the limited understanding of leaf color diversity and regulation. In this study, the chlorophyll and anthocyanin content of 137 germplasm resources were measured to explore the diversity and mechanism of leaf color formation in cultivated caladium. Association analysis of EST-SSR markers and pigment traits was performed, as well as metabolomics and transcriptomics analysis of a red leaf variety and its white leaf mutant. We found significant differences in chlorophyll and anthocyanin content among different color groups of cultivated caladium, and identified three, eight, three, and seven EST-SSR loci significantly associated with chlorophyll-a, chlorophyll-b, total chlorophyll and total anthocyanins content, respectively. The results further revealed that the white leaf mutation was caused by the down-regulation of various anthocyanins (such as cyanidin-3-O-rutinoside, quercetin-3-O-glucoside, and others). This change in concentration is likely due to the down-regulation of key genes (four PAL, four CHS, six CHI, eight F3H, one F3'H, one FLS, one LAR, four DFR, one ANS and two UFGT) involved in anthocyanin biosynthesis. Concurrently, the up-regulation of certain genes (one FLS and one LAR) that divert the anthocyanin precursors to other pathways was noted. Additionally, a significant change in the expression of numerous transcription factors (12 NAC, 12 bZIP, 23 ERF, 23 bHLH, 19 MYB_related, etc.) was observed. These results revealed the genetic and metabolic basis of leaf color diversity and change in cultivated caladium, and provided valuable information for molecular marker-assisted selection and breeding of leaf color in this ornamental plant.

Screening and identification of heat tolerance in Indian wheat genotypes using generalized regression neural network (GRNN) model

The present study using a generalized regression neural network (GRNN) model was carried out to check the effect of high temperature on five Indian bread wheat genotypes, namely, C306, K7903, CBW12, HD2329, and HD2428, and to develop an algorithm for the screening and identification of heat tolerance in wheat. A highly significant differential survivability in response to the temperature induction response technique with germinating seeds was observed for the five wheat genotypes. Maximum survivability was observed for C306 and K7903, whereas HD2329 and HD2428 showed minimum survival in response to lethal temperature stress. Similarly, at the mature plant stage, in response to heat treatment of 34°C/26°C (day/night), all five wheat genotypes showed a significant difference in chlorophyll a fluorescence, total chlorophyll content, and the reduction of 1,1- diphenyl-2-picryl-hydrazyl (DPPH) in response to heat treatment. The genotypes, C306, K7903, and CBW12 showed better performance for all the chlorophyll a fluorescence parameters under study including Fo, Fv/Fm, qL, qP, NPQ, θPSII, ETR, along with the total chlorophyll content and DPPH reduction, in contrast, the genotypes, HD2329 and HD2428 performed poorly for all parameters including chlorophyll a fluorescence parameters, total chlorophyll, and DPPH reduction. Higher inflection temperature and peak temperature were observed in C306 and K7903, in contrast, HD2329 and HD2428 showed significantly lower inflection temperature and peak temperature. Higher expression of the selected genes involved in photosynthesis and ROS scavenging was observed in C306 and K7903 relative to HD2329 and HD2428. On the basis of the different chlorophyll a fluorescence parameters, the algorithm was developed for the calculation of the heat susceptibility index. The algorithm was independently checked for the identification and segregation of all the five wheat genotypes taken in this study as tolerant, moderate, and susceptible. For all the genotypes, the algorithm was able to predict the heat susceptibility of the genotypes with high accuracy. Hence, the algorithm in combination with chlorophyll a fluorescence can be used for the screening of wheat and other plant species in response to abiotic stress, especially heat stress.

Lead and Zinc tolerance and accumulation in metallicolous and non-metallicolous populations of Peganum harmala L: potential use in phytostabilization

Peganum harmala L., commonly known as Harmal, is an aromatic and medicinal plant that grows in North Africa. P harmala is a pseudometallophyte that occur both in heavy metals contaminated and non contaminated soils . In order to identify the best adapted and suitable populations within P. harmala species, a comprehensive analysis and evaluation of the morphological, physiological, and biochemical responses to lead (Pb) and zinc (Zn) were performed in three metallicolous populations (MP) and a non-metallicolous one (NMP). In Zaida, Mibladen, and Aouli Morrocan sites, P. harmala growing soils show a low organic matter content, high Pb and Zn concentrations, and a pollution index higher than 1, indicating a significant contamination level. The effects of Pb and Zn on growth, physiological, antioxidant enzyme activities, and Pb/Zn accumulation capacity were compared between a NMP and three MP of P. harmala. Plants were grown in hydroponic culture with 100 µM of ZnSO4 or 100 µM of Pb(NO3)2 for 15 days. Our results show that Pb and Zn significantly decreased the aboveground biomass in the NMP, MP-Mibladen, and MP-Aouli compared to MP-Zaida. Pb and Zn decreased significantly the root biomass in the NMP compared to the MP. There is no significant difference in chlorophyll a and b contents between NMP and MP. Under Pb exposure, anthocyanin content is shown to be significantly higher in MP-Zaida than in other populations. In contrast, there is no difference between NMP and MP under Zn stress. Proline content as well as the catalase, peroxidase, and ascorbate peroxidase activities was significantly higher in NMP than in MP under Pb and Zn exposure. In particular, lower proline content, and antioxidant activities were observed in MP-Zaida under the Pb and Zn exposure. Pb and Zn accumulations were significantly higher in the NMP than in the MP, both in roots and aboveground parts, showing that the NMP plants accumulated highly but tolerated less compared to the MP. In the present study, the MP-Zaida accumulated less Pb and Zn in their tissues and tolerated more than the other populations, suggesting this population as a good candidate for a phytostabilization strategy.

Effect of Time of Girdling on Leaf Photosynthetic Performance and Kiwifruit Quality Characteristics at Harvest and Post-Storage

The present study investigated the impact of cane girdling on the ‘Hayward’ kiwifruit cultivar, both in terms of leaf physiological functions and fruit quality attributes, at harvest and post-storage. Four treatments were conducted: the control cane girdling conducted separately in August (GA), in September (GS), and both in August and September (double girdling) (GAS), using different canes. The results indicated that the carbon assimilation rate was reduced in girdled canes. Nevertheless, girdling resulted in increased fruit dry matter (by 1.7%), weight (by 6.4%), and dimensions without altering fruit shape. Additionally, fruits produced on girdled canes exhibited higher total soluble solids content (by almost 13%) and TSS-to-TA ratio post-storage. There were no significant differences in chlorophyll and carotenoid concentrations, organic acids, and most sugars assessed, both at harvest and post-storage. There were no significant differences among the treatments at harvest regarding total phenolic compounds, except for total flavonoids, which were lowest in the GA treatment. Post-storage, girdling (especially GAS and GS) was found to enhance the fruits’ total phenols and total flavanols, as well as its antioxidant capacity (1.88 μmol equiv. Trolox g−1 FW based on DPPH assay under GS versus (0.53 μmol equiv. Trolox g−1 FW under control). Overall, cane girdling can improve the quality of kiwifruit in terms of both fruit size and functional fruit properties.

Interactive Effect of Conservation Tillage, Potassium and Magnesium Sulphate Fertilization on Dry Matter Production, Physiological and Yield Parameters, and Yield of Grain Cowpea

This study conducted in Kerala, evaluated the role of conservation tillage (zero tillage (ZT), minimum tillage (MT), and conventional tillage (CT)) with five treatment combination of potassium (12 kg/ha, 20 kg/ha, 40 kg/ha) and magnesium sulphate (60 kg/ha and 80 kg/ha) on total DMP, physiology and grain yield of the test variety Anaswara (cowpea). In pot culture study, application of K: MgSO4, 10:80 kg/ha resulted in highest total chlorophyll content. While higher chlorophyll a content was obtained with the levels 20:60 kg/ha, and highest total DMP was recorded with the application at 40:100 kg/ha. Different levels of K and MgSO4 nutrition positively influenced 100 seed weight and grain yield, while there found no significant difference on chlorophyll b content, days to flowering, and grains/pod with any of the treatments imposed. Higher values for test weight and grain yield were recorded with K: MgSO4 40:60 kg/ha. In field experiment, tillage practices failed to produce notable difference in chlorophyll a, chlorophyll b, total chlorophyll contents, chlorophyll a/b ratio, grains per pod and test weight. Early flowering (45 DAS) and highest total DMP up to 75 DAS were recorded under CT. ZT produced highest LAI, while highest grain yield was noted under MT practice (734.5 kg/ha). Nutrient treatments failed to produce significant differences in chlorophyll b and chlorophyll a/b ratio. However, application at 40:80 kg/ha produced highest LAI, and higher content of chlorophyll a and total chlorophyll content (1.34 mg/g). K:MgSO4 applied at 40:60 kg/ha recorded highest grain yield. LAI was recorded highest under ZT with K:MgSO4 at 40:80 kg/ha. MT + K:MgSO4 at 40:60 kg/ha reported highest chlorophyll a/b ratio (4.71). K: MgSO4 applied at 40:60 kg/ha produced highest grain yield (806 kg/ha). In interactions, MT + K: MgSO4 at 40:60 kg/ha registered highest grain yield (914.8 kg/ha). Overall, in terms of grain yield, the test crop responded well to MT with application of K: MgSO4 at 40:60 kg/ha.

Analysis of leaf chlorophyll content of paddy plants during vegetative stage grown in soil media containing macroalgae organic fertilizer

Chlorophyll is a green pigment in leaves that functions to absorb light energy for photosynthesis. The value of chlorophyll concentration in leaves indicates the health status of a plant and healthy plants will produce more fruit. The purpose of this study was to determine the effect of chemical fertilizer (CF) and solid algae fertilizer (SAF) with different doses on the concentration of chlorophyll in paddy leaves. This research is important to do to determine the potential of macroalgae in reducing the dose of chemical fertilizer use in agricultural activities. In this study, paddy plants were given four different treatments, namely control (without CF and SAF); 100% chemical fertilizer (CF); 100% solid algae fertilizer (SAF); 50% chemical fertilizers and 50% solid algae fertilizers (CF+SAF). Each treatment consisted of ten pots. The results showed that the administration of SAF in the form of a combination of SAF 50% and CF 50% had a significant effect on the increase of chlorophyll b content of the leaves of paddy plants. However, there were no significant difference in chlorophyll a content between CF and CF+SAF group. Current results show that addition of SAF could potentially increase growth quality in paddy plants due to the increase of chlorophyll b content which absorbs higher frequency of blue light for photosynthesis.

Emersion-Associated Responses of an Intertidal Coral and Its Suitability for Transplantation to Ecologically Engineer Seawalls

There is a growing interest in transplanting corals onto the intertidal section of artificial coastal defences (e.g., seawalls) as an ecological engineering strategy to enhance biodiversity on urban shores. However, this inevitably results in exposure to the harsh environmental conditions associated with emersion (aerial exposure). Although the effects of a multitude of environmental stressors on corals have been examined, their photophysiological and gene expression responses to emersion stress remain understudied, as does the among-genotype variation in these responses. In this study, we conducted an in situ experiment to test the effects of increased daily emersion duration on a locally common intertidal coral, Dipsastraea cf. lizardensis. Coral fragments (n = 3) from five genotypically distinct colonies were subjected to two treatments: (1) increased daily emersion duration (~4.5 h d−1) and, (2) control (~3 h d−1) for three consecutive days during spring low tide. We examined the post-experimental photophysiological responses and expression level of a stress-associated gene, Hsp16. Relative to the controls, coral fragments that were exposed to longer daily emersion duration displayed significantly reduced effective quantum yield, while endosymbiont density varied significantly among genotypes across the experimental conditions. We found no significant differences in chlorophyll a concentration and Hsp16 gene expression level, suggesting that changes in these processes may be gradual and the duration of treatment that the corals were subjected to is likely within their tolerance limits. Taken together, it appears that D. cf. lizardensis displays substantial capacity to cope with sup-optimal conditions associated with emersion which makes it a promising candidate for transplantation onto intertidal seawalls. However, within-species variation in their stress response indicates that not all genotypes respond similarly to emersion, and this should be taken into account when selecting donor colonies for transplantation.

Inactivation of phosphate regulator (SphU) in cyanobacterium Synechocystis sp. 6803 directly induced acetyl phosphate pathway leading to enhanced PHB level under nitrogen-sufficient condition

Poly-β-hydroxybutyrate (PHB) is a biodegradable and biocompatible polymer that has potential in the fields of environmental, agricultural, and biomedical sciences. Cyanobacteria are considered an excellent source of PHB by bioconversion of CO2. This study aimed to prolong PHB production under nitrogen-sufficient condition in the model cyanobacterium Synechocystis sp. PCC 6803. Interestingly, the lack of phosphate regulator (SphU) enabled the mutant strain (ΔSphU) to have the ability to accumulate phosphate with higher expression of Pho regulon. When strain ΔSphU was cultured in nitrogen complete medium for 14 days, the PHB granules were more extensively accumulated in the ΔSphU strain than in the wild type. Photosynthesis activity slightly increased in ΔSphU strain, with no significant difference in chlorophyll a content between wild-type and ΔSphU strain in nitrogen-containing medium, indicating that the higher PHB content (14.57% (w/w) cell dry weight) was not influent of chlorosis. The RT-qPCR analysis revealed that genes involved in PHB biosynthesis and acetyl phosphate pathway were more upregulated in ΔSphU strain. Moreover, the level of acetate production in ΔSphU cells was higher than that in the wild type, suggesting that the deletion of the phosphate regulator could directly induce PHB metabolism by activation of the acetyl phosphate pathway. This research provides better understanding of PHB production regulation in cyanobacteria which are a promising hosts for industrial production of biodegradable plastics.

Non-Invasive Rapid Method to Evaluate Tunisian Virgin Olive Oil Based on color Measurement by Digital Images and Chlorophyll-Carotenoids Content

Color and pigment analyses are not required by the majority of olive oil marketing standards. However, it is a basic attribute that is highly associated, by most consumers, with the idea of quality. In this study, we aim at providing a fast non-invasive method for routine analysis that can be used on a large scale in the laboratories of olive oil analysis starting from pigment quantification and color range measurements. A selection of 172 virgin olive oil samples obtained in Tunisia between 2018 and 2019 were used for this purpose. Chlorophyll and carotenoid contents were analyzed using a UV spectrophotometer standard method while color range was measured using digital images taken under controlled conditions. All samples showed high significant differences in chlorophyll and carotenoid contents (p &lt;0,01) confirming that the visual selection of the set of samples was satisfactory for this study. Chlorophyll content varied from 3,0 to 28,3 ppm for samples SM137 and SM96 respectively, while carotenoids ​​oscillated between 0,7 and 6,2 ppm for SM138 and SM100 respectively. Principal component analysis using chlorophyll and carotenoids contents along with RGB-CYMY color measurements showed a higher significant correlation P&lt;0,05 between pigment contents and Red, Green, Blue and Yellow colors. Bivariate tests suggest that although color and pigments are correlated, color range assessment using digital imaging may represent a more sensitive method to discriminate olive oil according to cultivar, geographical origin, maturation index and year of harvest.

Energy dissipation and photosynthetic electron flow during the transition from juvenile red to mature green leaves in mango (Mangifera indica L.)

Leaf colouration during development from juvenile red to mature green leaves is a genetically controlled process in mango (Mangifera indica L.). This study aimed to determine the pigmentation pattern and electron transport flow in both red and green leaves under varied light intensity. In this study, 5- and 10-day old juvenile red and mature green leaves, respectively, were used. Three different photosynthetic active radiation levels (600 ± 5, 1000 ± 5 and 1200 ± 5 µmol m−2 s−1) were chosen to examine chlorophyll a fluorescence (O-J-I-P) transients. The vacuole of spongy cells in mesophyll contained anthocyanin in the juvenile leaf and rapidly degraded during the colour transition from red to green. A significant difference in chlorophyll, carotenoid and anthocyanin pigments was observed in both leaf types. The O-J-I-P parameters revealed that light intensity has a greater influence on the PSII electron transport chain than on PSI. Furthermore, the PSI of both leaves appeared to be more tolerant than that in PSII. The red leaf performed more energy dissipation than the green leaf after elevated light intensity exposure. O-J-I-P transients can be used as a sensitive, non-destructive method for measuring energy dissipation induced by intense radiation in plants.

Lettuce Growth, Nutritional Quality, and Energy Use Efficiency as Affected by Red–Blue Light Combined with Different Monochromatic Wavelengths

Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find the optimal combination of light wavelengths for lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m−2·s−1, and mixing, respectively, with 50 μmol·m−2·s−1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m−2·s−1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The Pn under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, Pn, and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher Pn, ΦPSII, and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and Pn of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.

Physiological characterization and transcriptome analysis of a chlorosis mutant in pak choi

Leaf color mutants are not only ideal resources for studying the physiological mechanisms of plant photosynthesis, but they are also selection markers for hybrid production. In this study, the chlorosis mutant ‘564Y’ and its wild-type counterpart ‘564’ were used to explore physiological characteristics and gene expression in pak choi. Compared with those of wild type, the dry weight and fresh weight of ‘564Y’ were significantly reduced, but the hypocotyl length of ‘564Y’ was longer. Pigment analysis showed that the chlorophyll a and carotenoid contents of ‘564Y’ were lower than those of wild type. However, there was no significant difference in chlorophyll b content between these two varieties. The photosynthetic capacity of ‘564Y’ was lower than that of ‘564’, and the photosynthetic electron transfer ability and light energy conversion efficiency were weaker in the former. Transmission electron microscopy showed that the chloroplast structure of ‘564Y’ was not compact, the thylakoid structure was irregular, and the number of matrix, grana, and stacking layers was decreased. Transcriptome analysis revealed 2958 differentially expressed genes (DEGs), and 78 gene ontology terms and 35 Kyoto Encyclopedia of Genes and Genomes pathways were significantly enriched. Among the DEGs, nine genes were associated with the chlorophyll synthesis pathway (Bra031690, Bra012595, Bra005677, Bra022628, Bra026410, Bra032155, Bra039206, Bra029875, and Bra012511) and one gene was associated with photosynthesis (Bra038011). Among these genes, 3 were identified as related to auxin metabolism too (Bra032155, Bra039206, and Bra029875). Their differential expression in the ‘564Y’ mutant and wild-type plant was confirmed by qRT-PCR. These results lay the foundation for future genetic and functional genomic studies in pak choi.

Physiological differences of ‘Crocantela’ lettuce cultivated in conventional and hydroponic systems

ABSTRACT Conventional soil and hydroponic growing systems have inherent differences in water and nutritional availability. These differences may affect plant physiological development and biochemistry. The objective of this study was to evaluate lettuce (Lactica sativa) cv. ‘Crocantela’development in either a hydroponic system or in soil through analyses of vegetative growth; chlorophyll abundance; and sugar and starch content. We evaluated the dry mass (DM), fresh mass (FM), number of leaves (LN), stomatal density and contents of chlorophyll, carotenoids, sugars and starch. Due to the improved nutritional conditions, especially in relation to macronutrients, plants grown in hydroponic system presented significant differences in chlorophyll a (0.4481 mg/g), b (0.1233 mg/g) and total chlorophyll content (0.5714 mg/g), as well as greater biomass when compared to plants cultivated in pots (FM: 342.69 g; DM: 21.13 g; NL: 17.75 g). The lower water availability for plants cultivated in pots influenced the increase in carbohydrate concentration and stomatal density in leaves (adaxial: 45.83 stomates/mm2; abaxial: 64.75 stomates/mm2) of lettuce plants.

Phytoplankton community-level bio-optical assessment in a naturally mercury contaminated Antarctic ecosystem (Deception Island)

Mercury naturally contaminated environments, like Deception Island (Antarctica), are field labs to study the physiological consequences of chronic Hg-exposure at the community level. Deception Island volcanic vents lead to a continuous chronic exposure of the phytoplanktonic communities to potentially toxic Hg concentrations. Comparing Hg-contaminated areas (Fumarolas Bay - FB, Gabriel de Castilla station - GdC station), no significant differences in chlorophyll a concentrations were detected, indicating that biomass production was not impaired by Hg-exposure despite the high Hg levels found in the cells. Moreover, the electron transport energy, responsible for energy production, also presented rather similar values in phytoplankton from both locations. Regarding FB communities, although the cells absorbed and trapped lower amounts of energy, the effect of Hg was not relevant in the photochemical work produced by the electronic transport chain. This might be due to the activation of alternative internal electron donors, as counteractive measure to the energy accumulated inside the cells. In fact, this alternative electron pathway, may have allowed FB communities to have similar electron transport energy fluxes without using respiration as photoprotective measure towards excessive energy. Hg-exposed cells also showed a shift from the energy flux towards the PS I (photosystem I), alleviating the excessive energy accumulation at the PS II (photosystem II) and preventing an oxidative burst. Our findings suggest a higher energy use efficiency in the communities exposed to volcanic Hg, which is not observable in cultured phytoplankton species grown under Hg exposure. This may constitute a metabolic adaptation, driven from chronic exposure allowing the maintenance of high levels of primary productivity under the assumingly unfavourable conditions of Deception Island.

Response of Platanus orientalis leaves to urban pollution by heavy metals

Atmospheric pollution is an important concern in urban environments. The impact of urban pollution on the physiological, biochemical and anatomical properties of leaves of oriental plane (Platanus orientalis L.) was studied. The leaves were collected from an urban site (Tehran, Iran) and a non-urban forest park (Chitgar Forest Park). Anatomical (stomata, parenchyma, and cuticle) and physiological (chlorophyll content, enzyme activities) properties were analyzed. The concentrations of Cd (cadmium), Pb (lead), Ni (nickel), and Cr (chromium) in leaves were significantly higher and Zn (zinc) lower at the urban site relative to the forest park. Chlorophyll a, total chlorophyll, and carotenoid content in leaves of the urban site were significantly less than those of the forest park, but there was no significant difference in chlorophyll b. In addition, the activities of superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase in urban leaves were significantly higher than in the leaves of the forest park. In the urban area, leaves experienced a significant decrease in leaf surface area, stomata density, stomata pore area, epidermis, and spongy mesophyll thickness, but a significant increase in cuticle and palisade thicknesses relative to forest park leaves. The increase in enzyme activities may indicate that the trees are attempting to cope with increased reactive oxygen species (ROS) because of pollution-induced stress. Our study suggests that oriental plane trees alter their physiological and anatomical properties when living in a polluted urban environment.

Tale of Two Storms: Impact of Extreme Rain Events on the Biogeochemistry of Lake Superior.

Climate change is expected to profoundly affect the Great Lakes region of North America. An increase in intensity and frequency of rain events is anticipated to deliver more runoff and to increase riverine inputs to Lake Superior's ecosystem. The effects of these changes on key biogeochemical parameters were analyzed by coupling satellite data, water column sensor profiles, and discrete surface-water sampling after two "500-year" flood events in the Lake Superior basin. This study provides both a spatial and a temporal sense of how plumes interacted within the ecosystem. We also determined the significant differences in water quality parameters for plume versus non-plume waters. These two plumes were important for delivery of nutrients, with variable transport of sediments and colored dissolved organic matter (CDOM). Data from the 2012 storm event showed a significant input of total nitrogen (TN), total phosphorous (TP) and CDOM to the system. In the 2016 storm event, carbon cycling parameters (acidity, total inorganic carbon (TIC), and dissolved organic carbon (DOC), and ammonia levels were elevated within the plume. In neither storm event was there a significant difference in chlorophyll a between plume and non-plume waters during our sampling cruises. These two plume events were similar in amount of precipitation, but their effect on the biogeochemistry of Lake Superior varied due to differences in the watersheds where the rain fell. The studied plume events were dynamic, changing with currents, winds and the settling of suspended sediments.

Response of Pond‐raised Fingerling Hybrid Catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus, to Dietary Protein Concentrations and Sources

AbstractThis study examined four experimental diets with different protein concentrations and sources for pond‐raised fingerling hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus. A 35% protein diet with fishmeal was used as the control diet. Test diets were 32 and 28% all‐plant‐protein diets and a 28% protein diet with porcine meat, bone, and blood meal. Small fingerlings with a mean initial weight of 2.9 g/fish were stocked into 20 earthen ponds (0.04 ha) at a density of 172,970 fish/ha. They were fed once daily to apparent satiation for 107 d. No significant differences were observed for total diet fed, gross yield, final weight, survival, or condition factor among dietary treatments. However, fish fed the 28 and 32% all‐plant‐protein diets had a significantly higher feed conversion ratio than fish fed the 35% protein diet with fishmeal. There were no significant differences in chlorophyll a and nitrite concentrations in the pond water, but ponds receiving the 35% protein diet had significantly higher ammonia than those receiving 28% protein diets. Economic analysis suggested potential cost savings by using low‐protein and all‐plant‐protein diets for hybrid catfish fingerling production.

In vitro and in vivo effects of Pseudomonas spp. and Bacillus sp. on Fusarium acuminatum, Botrytis cinerea and Aspergillus niger infecting Cucumber

Cucumber (Cucumis sativus L) is an important member of the Cucurbitaceae family. Production of healthy nursery is necessary for high-quality production of this crop in greenhouses and in fields. With the idea of minimizing the use of pesticides and mineral fertilizers to preserve soil quality, we investigated the effects of plant growth promoting bacteria (PGPB) on growth promotion and protection of cucumber plants from phytopathogenic fungi. The effects of Pseudomonas spp. strains with different antifungal activities and Bacillus sp. Q10 strain with PGP activity were tested on cucumber plants. Antagonistic activity of Pseudomonas spp. against the growth of several phytopathogenic fungi isolated from cucumber: F. acuminatum, B. cinerea and A. niger, was observed. The influences of overnight cultures, supernatants and heat-stable antifungal factors were tested on the phytopathogenic fungi in vitro. Pseudomonas sp. K35 and K24 strains were more effective than P. chlororaphis Q16 and Pseudomonas sp. K27, showing 70-80% of fungal growth inhibition regardless of culture or fraction applied. The good antagonists that belong to pseudomonads and Bacillus sp. Q10 strain were used as mixtures for estimation of plant growth and health promoting effects on cucumber plants. Growth dynamics differed depending on the applied strain of Pseudomonas sp. The M3 treatment (a mixture of Bacillus sp. Q10 and P. chlororaphis Q16) stimulated the initial phase of growth, while M4 (a mixture of Bacillus sp. Q10 and Pseudomonas sp. K24) resulted in the maximal height at the final measurement. Significant differences in leaf and plant weight (M4), and leaf weight (M5, containing K35 strain) were found after the treatments. No significant differences in chlorophyll and NBI level were observed in any of the tested combinations. The obtained results suggested that M3 was suitable for stimulation of the early phase of cucumber growth, while the mixtures M4 and M5 improved plant protection and stimulated the later phases of cucumber growth.

Hybrid sorrel (Rumex tianschanicus × Rumex patientia) a high biomass yielding plant as an interesting object of physiological research

Hybrid sorrel (Rumex tianschanicus × Rumex patientia) a high biomass yielding plant as an interesting object of physiological research