Photosynthesis Pigments Research Articles

Correlation of arbuscular mycorrhizal dosage with level of colonization, nutrient concentration, and photosynthesis pigment of Cavendish banana plant

The commercial development of Cavendish bananas still faces many obstacles, including the availability of seedlings/suckers at low prices, so technological substitution is needed to stimulate the growth of Cavendish banana suckers in the form of arbuscular mycorrhizal (AM) biological agents. The research aims to determine the correlation between AM doses and colonization levels, tissue nutrient concentrations, and photosynthetic pigments in Cavendish banana seedlings/suckers. It is also a novelty in this research study. The research was carried out in Parepare city at coordinates 3°59'30.204" S; 119°38'42.936" E using four AM doses as independent variables, namely 0 g, 5 g, 10 g, and 15 g pot-1. The variables observed (dependent variables) were the level of colonization, nutrient concentration in the tissue, and photosynthetic pigment content. Using Microsoft Excel software, statistical tests, regression, and correlation analyses were conducted to see the relationship between treatment (independent variable) and observed parameters (dependent variable). The research showed that AM dosage was positively correlated with the level of root colonization, the concentration of N, P, and K elements in the tissue, and the photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids). A dose AM of 15 g pot-1 gave a better effect on Cavendish banana suckers, which can be recommended for the development of Cavendish banana seedlings.

Genome-wide survey of chlorophyllase (CLH) gene family in seven Rosaceae and functional characterization of MdCLH1 in apple (Malus domestica) leaf photosynthesis

Chlorophyll, a crucial pigment in plant photosynthesis, undergoes dynamic synthesis and degradation processes throughout the growth cycle of plants. Chlorophyllase (CLH) plays a crucial role in the degradation of chlorophyll by removing the phytol group from chlorophyll A to produce chlorophyllide A. However, Rosaceae species remain underexplored in terms of understanding the functional divergences among CLH gene family members (CLHs) involved in chlorophyll catabolism and photosynthesis. The apple (Malus domestica) CLHs also requires further systematic characterization and identification. In this study, 20 CLHs (MdCLH1-4, FvCLH1-2, PpCLH1-2, PcCLH1-3, PaCLH1-2, RrCLH1-4, RcCLH1-3) were identified from seven species belonging to the Rosaceae family. The chromosomal distribution of these gene family members is mostly separate across all species, except in Rosa rugosa. The number of amino acids encoded by these genes ranges from 171 aa to 391 aa, possessing a theoretical isoelectric point (PI) of 5.46-9.59, and a relative molecular weight of 18313.07D to 42413.21D. Secondary structure predictions highlight α-helix and random coil conformations as the dominant structural elements of CLH proteins present in Rosaceae species. Subcellular localization predictions indicate that all CLH proteins are expressed in chloroplasts, while MdCLH4 is uniquely localized to the nucleus. Phylogenetic analysis reveals high homology and close evolutionary relationships among the genes in three subfamilies. All these 20 CLHs contain elements responsive to phytohormones, environmental stress, and light. Furthermore, transcriptomic profiling using geneChip expression array coupled with qRT-PCR analyses revealed a heightened transcriptional activity of MdCLHs in leaf tissues and protective tissue of annual shoots as compared to other plant components. Additional experimental evidence specifically indicates MdCLH1 is located in the chloroplasts of tobacco leaves. Notably, MdCLH1 transient expression in apple leaves decreased chlorophyll a, carotenoids, total chlorophyll content, non - photochemical quenching coefficient (NPQ), and intercellular CO₂ concentration (Ci), while increasing chlorophyll b content, effective PSII quantum yield [Y(II)], net photosynthetic rate (Pn), stomatal conductance (Gs), and electron transport rate (ETR). These suggest MdCLH1 enhances light energy conversion in PSII by modulating chlorophyll degradation, potentially improving photosynthetic efficiency and reducing the potential for photoinhibition. This study lays a solid foundation for further exploration into the functional roles of CLHs in the Rosaceae family.

Functional Characterisation of GmGASA1-like Gene in Glycine max (L.) Merr.: Overexpression Promotes Growth, Development and Stress Responses.

The presence of Gibberellic Acid-Stimulated Arabidopsis, GASA, gene family has been reported in many important plants, playing roles in various aspects of plant biology but little has been uncovered in soybeans. Soybean is one of the major plants providing nutrition for humans and livestock globally. In this study, we overexpressed a novel GASA gene (GmGASA1-like) in Glycine max and conducted bioinformatic analyses, evaluated the T2 transgenic line in an open field, and applied major stressors along with the growth promoter GA3 to investigate the potential functions of the GmGASA1-like gene. The results of bioinformatics implied that the GmGASA1-like gene is regulated by GA3, and its protein has the potential to influence key processes of plant growth and development. The transgenic plants (JN74-OE) were significantly taller and had a larger canopy in the field trial at the R1-growth stage and demonstrated superiority in some seed quantity and quality traits after harvesting. Under abiotic stresses (including cold, heat, and drought) and spraying of GA3, the level of GmGASA1-like gene expression in JN74-OE exceeded the levels measured before the treatments. Notably, the highest expression level was observed during the drought stress treatment. Photosynthesis pigments levels in both the overexpressed lines and the control group showed no significant differences. In summary, this study sheds light on the multifaceted roles of the GmGASA1-like gene, impacting soybean plant architecture, seed traits, and stress responses. Ultimately, this research paves the way for a more productive and sustainable soybean industry.

Non-Invasive Detection of Nitrogen Deficiency in Cannabis sativa Using Hand-Held Raman Spectroscopy

Proper crop management requires rapid detection methods for abiotic and biotic stresses to ensure plant health and yield. Hemp (Cannabis sativa L.) is an emerging economically and environmentally sustainable crop capable of yielding high biomass. Nitrogen deficiency significantly reduces hemp plant growth, affecting photosynthetic capacity and ultimately decreasing yield. When symptoms of nitrogen deficiency are visible to humans, there is often already lost yield. A real-time, non-destructive detection method, such as Raman spectroscopy, is therefore critical to identify nitrogen deficiency in living hemp plant tissue for fast, precise crop remediation. A two-part experiment was conducted to investigate portable Raman spectroscopy as a viable hemp nitrogen deficiency detection method and to compare the technique’s predictive ability against a handheld SPAD (chlorophyll index) meter. Raman spectra and SPAD readings were used to train separate nitrogen deficiency discrimination models. Raman scans displayed characteristic spectral markers indicative of nitrogen deficiency corresponding to vibrational modes of carotenoids, essential pigments for photosynthesis. The Raman-based model consistently predicted nitrogen deficiency in hemp prior to the onset of visible stress symptoms across both experiments, while SPAD only differentiated nitrogen deficiency in the second experiment when the stress was more pronounced. Our findings add to the repertoire of plant stresses that hand-held Raman spectroscopy can detect by demonstrating the ability to provide assessments of nitrogen deficiency. This method can be implemented at the point of cultivation, allowing for timely interventions and efficient resource use.

Mitigating chromium stress in tomato plants using green-silicone nanoparticles: Enhancing cellular oxidative stress management and chromium reduction

Nano-enabled approach has become the promising option for resolving heavy metal (HMs) contamination and improving the crop production. Here, current study explored mechanism involved in how green silicon nanoparticles (SiNPs) alleviating the chromium (Cr) induced toxicity in tomato. Green SiNPs in spherical shape with size 8–40 nm were synthesized with artemisia annua leaves extract and characterization performed by modern characterization method. The results of the green house experiment demonstrated that SiNPs at dose of 150 mg kg−1 surprisingly improved the biomass and root architecture of tomato plants. SiNPs supplementation also positively enhanced the photosynthesis pigments and leaf gas exchange attributes of Cr-stressed plants. Besides this, SiNPs150 mg kg−1 elevated antioxidant enzymes activities which scavenging ROS and reduced Cr-caused oxidative destruction. Furthermore, qPCR assay showed upregulation of the antioxidant defense related genes with the application of SiNPs under Cr stress. Transmission Electron Microscopy analysis showed that SiNPs application effectively alleviated Cr-induced damage to leaf ultrastructure and had a substantial impact on Cr and Si accumulation in plants. In conclusion, the utilization of green SiNPs as nano-fertilizers exhibits great potential as a strategy for agriculture to alleviate the adverse effects of HMs stress, safeguard food safety, and sustainable agriculture in the future.

Application of iron oxide nanoparticles improves growth and phytochemical constituents of in vitro cultured Carum copticum L.

Iron oxide nanoparticles (FeONPs) are widely used in various applications, such as biomedicine, environmental remediation, and agriculture. Moreover, FeONPs can affect the production of secondary metabolites in plants, which are compounds that have various biological and pharmacological activities. Therefore, in this study, the ajwain (Carum copticum L.) seeds were grown in MS medium containing different levels of FeONPs (0, 100, 200, and 400 mg l−1). After four weeks, the effects of FeONPs on growth, photosynthesis pigments, total phenolic, and anthocyanin content, activities of some antioxidant enzyme and secondary metabolites of ajwain) were investigated. The results showed that low levels of FeONPs (especially 200 mg l−1) increased fresh weight (231 %), total chlorophyll (49 %), total phenolics (259 %), anthocyanin content (110 %), as well as thymol (8 %) and γ-terpinene (16 %) content. Conversely, 400 mg l−1 FeONPs reduced root length (60 %) and fresh weight (64 %) was associated with a reduction in CAT activity, phenol (55 %), thymol (22 %), and γ-terpinene (18 %) content compared to ajwain treated with 200 mg l−1 FeONPs. This reduction was probably due to the increase in ROS caused by the low catalase enzyme activity and important essential oils compounds such as thymol and γ-terpinene. Thus, our results indicate that FeONPs at certain levels can be used as a new way for in vitro production of valuable essential oils and antioxidant compounds in ajwain.

Photosynthetic and Carbon Sequestering Ability of Safflower Leucea and Accumulation of Organic Carbon in Sod-Podzolic Soil

According to the content of photosynthesis pigments, the most active period of photosynthetically active radiation absorption by the leaves of Leucea safflower during the growing season was revealed. From the moment of full regrowth to flowering, the amount of chlorophylls a and b in the leaves was 6.2–8.5 mg/g of dry weight, carotene – 3–4 times less. During photosynthesis, the carbon content in the leaves of Leucea safflower practically did not change and amounted to 39.5–42.5%. The mass fraction of the main product of photosynthesis, sugars, increased from the regrowth phase to seed formation from 4.0 to 11.8%. During the period of active growth, the nitrogen content in the leaves of the leucea was 1.3–1.6, phosphorus – 1.1–1.6, potassium – 4.4–5.1%. After harvesting the safflower leucea of the 14th year of life, a high amount of сrop and root residues (CRR) was determined in the sod-podzolic soil – 13.7–17.3 t/ha. The amount of carbon absorbed during photosynthesis was 6.8–11.5 t C/ha (24.3–41.3 t CO2/ha), depending on the experiment variant, for natural phytocenosis this indicator was equal to 2.4 t C/ha (or 8.6 t CO2/ha) during the growing season. The organic carbon content under the safflower leucea of the 14th year of life in the 0–20 cm soil layer increased relative to the initial level by 3.6% in the version without fertilizers, by 15.1% in the N60P60K60 variant, and in the 20–40 cm layer by 8.8–42.6%, respectively. Relative to the virgin analogue, the carbon content in the 0–20 cm layer was 15.2–28.0 higher, in the 20–40 cm layer – 25.0–64.4%, depending on the experiment variant, which indicated the deposition of carbon in the form of humic substances due to its storage in deeper soil layers.

Multiwavelength Photoacoustic Doppler Flowmetry of Living Microalgae Cells.

Photoacoustics can provide a direct measurement of light absorption by microalgae depending on the photosynthesis pigment within them. In this study, we have performed photoacoustic flowmetry on living microalgae cells to measure their flow characteristics, which include flow speed, flow angle, flow direction, and, more importantly, the photoacoustic absorption spectrum, all by observing the photoacoustic Doppler power spectra during their flowing state. A supercontinuum pulsed laser with a high repetition frequency is used as the light source: through intensity modulation at a specified frequency, it can provide wavelength-selectable excitation of a photoacoustic signal centered around this frequency. Our approach can be useful to simultaneously measure the flow characteristics of microalgae and easily discriminate their different species with high accuracy in both static and dynamic states, thus facilitating the study of their cultivation and their role in our ecosystem.

Exploring the impact of exogenous melatonin on agro-morphological characteristics, carvacrol, and rosmarinic acid production in Satureja rechingeri Jamzad under drought stress

Satureja rechingeri Jamzad (known as “Jatra” in Persian), which belongs to the Lamiaceae family, is a rich source of essential oil particularly carvacrol, and rosmarinic acid. Drought stress has a detrimental impact on the physiological and biochemical parameters of plants, leading to a decline in plant productivity. Melatonin (MT), a new plant growth regulator found abundantly in plants, has been found to enhance the plant's internal resistance to various environmental stresses. The present study aimed to examine the impact of exogenously applied MT on the agro-morphological, physio-biochemical, and phytochemical traits of S. rechingeri plants cultivated under different levels of drought stress. The results indicated that plants treated with 200 µM MT obtained the highest plant height, length and width of leaf, fresh, dry and drug weight under different drought stress levels. The highest values of relative water content (RWC) (93.5%) and chlorophyll content (15.4 mg/g FW) were recorded by MT 200 µM and 100 µM, respectively, in 100% FC. Drought stress treatments (40, 60, and 80% FC) without foliar spray of MT significantly enhanced the H2O2 content, electrolyte leakage, and malondialdehyde content in leaves, whereas MT treatment under drought stress significantly decreased the above parameters. The lowest H2O2 content (11.5 nmol/g), electrolyte leakage (3.08%), and malondialdehyde content (0.78 µM/g) were obtained by 200 µM MT at 100% FC. In contrast, drought stress treatment increased the total phenol content (TPC), rosmarinic acid (RA), essential oils (EOs) content and yield, and carvacrol. The maximum values of TPC (28.1 mg GAE/g DW), EOs content (3.63%) and yield (0.96%), and carvacrol (95.66%) were achieved by 200 µM MT at 40% FC. The highest RA content (7.43 mg GAE/g DW) was recorded in 100 µM MT at 40% FC. Thus, foliar spray MT has the potential to enhance plant growth through the mitigation of reactive oxygen species (ROS)-induced oxidative harm, as well as the augmentation of photosynthesis pigments, secondary metabolites such as phenolics, EOs levels, overall antioxidant scavenging capacity, and the preservation of RWC during periods of drought stress.Graphical

Foliar-applied iron and zinc nanoparticles improved plant growth, phenolic compounds, essential oil yield, and rosmarinic acid production of lemon balm (Melissa officinalis L.).

Metallic nanoparticles (NPs) have been highlighted to improve plant growth and development in the recent years. Although positive effects of some NPs have been reported on medicinal plants, the knowledge for stimulations application of iron (Fe) and zinc (Zn) NPs is not available. Hence, the present work aimed to discover the effects of Fe NPs at 10, 20, and 30 mg L-1 and Zn NPs at 60 and 120 mg L-1 on growth, water content, photosynthesis pigments, phenolic content, essential oil (EO) quality, and rosmarinic acid (RA) production of lemon balm (Melissa officinalis L.). The results showed that Fe NPs at 20 and 30 mg L-1 and Zn NPs at 120 mg L-1 significantly improved biochemical attributes. Compared with control plants, the interaction of Fe NPs at 30 mg-1 and Zn NPs at 120 mg L-1 led to noticeable increases in shoot weight (72%), root weight (92%), chlorophyll (Chl) a (74%), Chl b (47%), RA (66%), proline (81%), glycine betaine (GB, 231%), protein (286%), relative water content (8%), EO yield (217%), total phenolic content (63%), and total flavonoid content (57%). Heat map analysis revealed that protein, GB, EO yield, shoot weight, root weight, and proline had the maximum changes upon Fe NPs. Totally, the present study recommended the stimulations application of Fe NPs at 20-30 mg L-1 and Zn NPs at 120 mg L-1 to reach the optimum growth and secondary metabolites of lemon balm.

Evaluation of Ca(NO3)2 and various container cell size effects on some growth attributes and nutrient content of tomato transplants

Optimizing container cell size and nutrition is crucial for enhancing the quality of vegetable transplants. The current study evaluated the effect of different cell sizes and Ca(NO3)2 on some properties of tomato (Solanum lycopersicum L.) transplants. Experimental treatment included four levels (0, 50, 100, and 150 mg L–1) of Ca(NO3)2 and 5 different cell sizes of containers (1, 2, 3, 4, and 5) in a factorial experiment based on a completely randomized design (CRD) with three replications under greenhouse conditions. Ca(NO3)2 and larger cell size, increased height, stem diameter, fresh and dry weights of roots and shoots, and concentration of chlorophyll, protein, SPAD, carbohydrates, and macro/micronutrients. The results revealed that maximum shoot and root fresh and dry weight, photosynthesis pigments, N, P, K, Ca, and Fe concentrations were recorded at 150 mg L–1 × cell size 5. In comparison, the highest Zn and Mn concentrations were recorded at 100 mg L–1 × cell size 4 and 5. Our results demonstrated that applying Ca(NO3)2 and increasing the cell size of the containers improved the traits evaluated, so Ca(NO3)2 at 10 and 15 mg L–1 with cell size 5 can be recommended to transplant producers.

Photophobotaxis in the filamentous cyanobacterium Phormidium lacuna: Mechanisms and implications for photosynthesis-based light direction sensing.

Cyanobacterium Phormidium lacuna filaments move from dark to illuminated areas by twitching motility. Time-lapse recordings demonstrated that this photophobotaxis response was based on random movements with movement reversion at the light-dark border. The filaments in the illuminated area form a biofilm attached to the surface. The wild-type and the pixJ and cphA mutants were investigated for photophobotaxis at diverse wavelengths and intensities. CphA is a cyanobacterial phytochrome; PixJ is a biliprotein with a methyl-accepting chemotaxis domain and is regarded as a phototaxis photoreceptor in other species. The cphA mutant exhibited reduced biofilm surface binding. The pixJ mutant was characterized as a negative photophobotaxis regulator and not as a light direction sensor. 3-(3,4-dichlorophenyl)1,1-dimethylurea (DCMU) blocks electron transfer in PS II. At concentrations of 100 and 1000 μM DCMU, photophobotaxis was inhibited to a greater extent than motility, suggesting that PSII has a role in photophobotaxis. We argue that the intracellular concentrations of regular photoreceptors, including CphA or PixJ, are too small for a filament to sense rapid light intensity changes in very weak light. Three arguments, specific inhibition by DCMU, broad spectral sensitivity, and sensitivity against weak light, support photosynthesis pigments for use as photophobotaxis sensors.

Characterization of Physiology, Photosynthesis, and Nutrition Based on Induced Deficiencies of Macro- and Micronutrients in Basil (Ocimum basilicum L.)

Basil (Ocimum basilicum L.) contains abundant nutrients and is considered an economically important edible vegetable. The optimal nutrient levels will increase the productivity and basil quality. However, prominent research on basil regarding the diagnostic nutrient deficiency standard and the corresponding nutrient uptake is still scarce. To this end, the basil plants were hydroponically cultured and subjected to one of 14 nutrient solution treatments, corresponding to the omission of a single nutrient element (designated as -N, -P, -K, -Ca, -Mg, -NH4+, -NO3−, -S, -Fe, -Mn, -B, -Zn, -Mo, and -Cu) and a complete nutrient solution (CS) as the control. The most common nutrient deficiency symptoms were chlorosis, stunted roots and growth, and even leaf necrosis and abscission, in particular of -N, -P, -NO3−, and -Fe. We also found that basil is a NH4+-sensitive species. The photosynthetic capacity (photosynthesis pigments, Fv/Fm ratio, and greenness index) was disturbed to varying degrees when a single nutrient was omitted from the nutrient solution. Additionally, the omission of a specific single nutrient confers significant differences in the tissue nutrients, regardless of the macronutrients and micronutrients considered. Concomitantly, multivariate analysis suggested the correlations among certain important nutrients were distinctly different under different treatments (correlation analysis); the influences of different nutrient deficiencies on the tissue nutrient concentrations showed similarity (principal component analysis). Collectively, the growth, physiological, and biochemical changes studied in this trial not only improved our knowledge for diagnosing nutrient deficiency symptoms for practical cultivation but also provided a comprehensive understanding of the internal nutrient associations in basil.

Exploring the microscopic eyeball of cyanobacteria: A comprehensive review

Cyanobacteria resemble algae in that they contain chlorophyll and then photosynthesize and oxygen is released as a result. Cyanobacteria resemble bacteria in that they are Gram-negative bacteria and their wall consists of peptidoglycan and contain a primitive nucleus and do not contain chloroplasts but membranes called thylakoids that contain the chlorophyll pigment for photosynthesis. Cyanobacteria produce their own energy through photosynthesis, just like plants. Scientists from America said that they made an "energy generator" using a bottle containing bacteria and sewage, and that the efficiency of these "microbes connected to wires" reached 30%, which is equivalent to the efficiency of the best solar cells currently commercially available. The researchers explained in their study, the results of which were published in the Proceedings of the American Academy of Sciences, that it is still necessary to find a suitable metal to manufacture an important part of this small "generator", which is a cathode, which is the electrode of the electrical circuit where the process of reducing electrons occurs, as an alternative to the silver oxide that they currently use. The idea of using bacteria as a source of energy generation is not new, and through this idea, bacteria that live on natural waste can be exploited and release excess electrons through a complex mechanism of cells during this process that leads to the conversion of chemical energy into an electric current. It is expected that water purification plants will be the place for these microbial generators, as public wastewater is rich in natural materials, in addition to the fact that not only will electricity be produced there, but the water will be purified at the same time, which reduces the operating costs of these stations. However.

Impact of biostimulants based amino acids and irrigation frequency on agro-physiological characteristics and productivity of broccoli plants

Abstract scientists are concerned about the utilizing of biostimulants-based amino acids in plant feeding and mitigating negative effects of water stress. As a result, two-year field experiments were conducted at Faculty of Agriculture's experimental station at Cairo University to study the effectiveness of liquid yeast waste (CMS) and Cargo amino acids (AAs) on the agro-physiological features of broccoli plants with different irrigation frequencies (every 5, 10, and 15 days). Compared with control plants, the foliar application of AAs and CMS significantly increased plant height, photosynthesis pigments, head weight, head diameter, head height, plant yield, and quality at different irrigation frequencies. Likewise, both treatments (CMS and AAs) significantly improved ascorbic acids by 16.65% and 15.95% and increased total phenol content by 24.10% and 36.60%, respectively, compared to control plants. Accordingly, the highest productivity was achieved for broccoli grown under irrigation every five days with the CMS bio-stimulant, where it was 3111.17 kg ha-1, while the lowest productivity was achieved for the control treatment in which no biostimulants were added and irrigation frequency every 15 days, and the productivity was 1376.22 kg ha-1. Plants irrigated every 15 days produced the highest levels of abscisic acid (ABA) and superoxide dismutase (SOD), followed by plants irrigated every 10 days and every 5 days. Exogenous application of amino acids bio-stimulants could be suggested to improve vegetative growth, biochemical characteristics, productivity, and nutritional value as well as to mitigate negative effects of water scarcity.

The Influence of Heavy Metal Pollution on the Pigment Content in the Assimilation Apparatus of Poplar Cultivars in the Conditions of the Iron Ore Region

Abstract We carried out studies of the translocation of heavy metals in the soils of Kryvyi Rih. The peculiarities of the accumulation of heavy metals in the assimilation apparatus of seven poplar cultivars were clarified. The maximum rates of translocation of heavy metals were detected at the monitoring site of the industrial site of Northern Iron Ore Dressing Combine (henceforth referred to as Pivnichnyi HZK or PivnHZK). In the leaves of poplars “Lvivska,” “Hradizhzka,” and “I-45/51,” cadmium, one of the highly toxic elements, accumulates 25–30 times more than in the leaves of control plants. High rates of accumulation of heavy metals lead to a violation of the functioning of the plant organism at the physiological and biochemical levels, as evidenced by changes in the content of chlorophyll a and b. The amount of the main pigments of photosynthesis in the leaves of poplar cultivars under conditions of environmental pollution with heavy metals is lower than in the control, which indicates the inclusion of plant signaling mechanisms. At the same time, the amount of carotenoids in the organs of assimilation of poplars growing on the industrial sites of Northern and Central Iron Ore Dressing Combines (henceforth referred to as Central HZK or CHZK) increases and indicates the realization of their protective functions. The investigated cultivars can be divided into two groups according to the intensity of changes in pigment content. The first group (with a decrease in chlorophylls up to 2 times and an increase in the amount of carotenoids up to 2.5 times) includes “I-45/51,” “Lvivska,” and “Hradizhzka,” and the second group (with a decrease in chlorophylls by more than 2 times and an increase in the amount of carotenoids by more than 2.5 times) includes “Keliberdynska,” “Robusta,” “Sacrau-59,” and “Tronco.” This fact indicates better adaptation and greater resistance of cultivars of the first group to the action of heavy metals.

Peculiarities of soybean-rhizobial systems subject to different levels of water supply fol-lowing treatment with succinic acid and epibrassinolide

All around the world, one of the leading – according to area of cultivated fields – oleic crops is soybean, which has a high demand for moisture. Given the significance of this crop and negative impact of drought on its yield, integrated research of the influence of insufficient water supply on the intensity of physiological-biochemical processes in those plants is necessary for identifying and understanding the drought-tolerance mechanisms of soybean, as well as symbiotic systems created with its participation, and also for search for ways to adapt it to this stressor. Therefore, our objective was determining the specifics of formation and functioning of the symbiotic systems of soybean and Bradyrhizobium japonicum, following treatment with succinic acid (0.01 g/L) and 24-epibrassinolide (0.00001 g/L), subject to different levels of watering. Our studies revealed that pre-sowing treatment of the seeds with a solution of 24-epibrassinolide with their subsequent inoculation with B. japonicum Т21-2 resulted in the most pronounced stimulation of formation and functioning of the symbiotic systems of soybean in the optimal growing conditions. At the same time, during water shortage, the intensity of nitrogen fixation was the highest in the plants grown from seeds that had been successively treated with the acid and the inoculant. We confirmed that water deficit led to significant increase in the overall content of phytohormones of cytokinin nature in the soybean root nodules, depending on the way the seeds were treated. However, the largest pool of cytokinins was seen in the plants that had been treated with succinic acid against the background of both optimal and insufficient water supply. Treatment of the seeds with 24-epibrassinolide caused significant excess of content of zeatin riboside over the content of zeatin during the flowering stage, whereas in the stage of pods formation it led to an opposite effect – excess of zeatin over zeatin riboside. Fourteen days-long water deficit decreased the content of chlorophylls in the leaves and grain productivity of the plants of all variants of the experiment. The use of growth regulators managed to alleviate the negative impact of stress and protect the pigment complex from ruination. Treatment of the seeds with solutions of succinic acid and 24-epibrassinolide provided the growth of soybean grain productivity regardless on water-supply level. The most efficient was 24-epibrassinolide. Therefore, use of 24-epibrassinolide for pre-sowing treatment of the soybean seeds provided formation of effective symbiotic systems with high nitrogen-fixing activity and caused a number of specific changes in the pattern of accumulation of free and complex forms of cytokinins in the root nodules of those plants. At the same time, the treatment provided the highest concentration of photosynthesis pigments in the soybean leaves, and as a result produced the greatest increase in grain productivity of plants of all the variants, regardless of levels of water supply. In turn, use of succinic acid produced the highest level of nitrogen-fixing activity in the case of the lowest number of root nodules in the conditions of insufficient water supply, and also caused significant accumulation of cytokinins in the nodules, compared with other studied variants against the background of both optimal and insufficient water supply. Therefore, it did result in increase in soybean grain productivity, but this was lower than in the plants treated with 24-epibrassinolide.

Reducing chlorophyll levels in seed-filling stages results in higher seed nitrogen without impacting canopy carbon assimilation.

Chlorophyll is the major light-absorbing pigment for plant photosynthesis. While evolution has been selected for high chlorophyll content in leaves, previous work suggests that domesticated crops grown in modern high-density agricultural environments overinvest in chlorophyll production, thereby lowering light use and nitrogen use efficiency. To investigate the potential benefits of reducing chlorophyll levels, we created ethanol-inducible RNAi tobacco mutants that suppress Mg-chelatase subunit I (CHLI) with small RNA within 3 h of induction and reduce chlorophyll within 5 days in field conditions. We initiated chlorophyll reduction later in plant development to avoid the highly sensitive seedling stage and to allow young plants to have full green leaves to maximise light interception before canopy formation. This study demonstrated that leaf chlorophyll reduction >60% during seed-filling stages increased tobacco seed nitrogen concentration by as much as 17% while canopy photosynthesis, biomass and seed yields were maintained. These results indicate that time-specific reduction of chlorophyll could be a novel strategy that decouples the inverse relationship between yield and seed nitrogen by utilising saved nitrogen from the reduction of chlorophyll while maintaining full carbon assimilation capacity.

Impacts of Atlantic water intrusion on interannual variability of the phytoplankton community structure in the summer season of Kongsfjorden, Svalbard under rapid Arctic change

Atlantification, known as impacts of high-latitude Atlantic water inflows on the Arctic Ocean has strengthened owing to climate change, corresponding to the rapid ice retreat in the Arctic. The relationship between phytoplankton and environmental changes in the Arctic on the interannual scale is unclear because of the lack of long-time series data. In this study, we discuss the ecological response to Atlantic water intrusion in the Kongsfjorden,Svalbard. We measured chlorophyll a and photosynthesis pigments for the water column samples from a fixed section along the Kongsfjorden to study the response of phytoplankton biomass and communities to Atlantic water intrusion in the summer season from 2007 to 2018. The results showed that dinoflagellates, prasinophytes, cryptophytes, and chlorophytes consistently accounted for over 50% of the total biomass, with the distinct annual variation of chlorophyll a. Bioavailable nitrogen was the main limiting factor on phytoplankton growth in the study area, as inferred by its concentration and nutrients ratios. The relationship between phytoplankton and water mass analysis suggested that the intrusion of Atlantic water in Kongsfjorden may cause interannual variability of the phytoplankton biomass and community structure by influencing the nutrient supply and water stratification in the fjord region. Our study provides insights into the ongoing impact of Atlantification on the phytoplankton community in the Arctic fjord.

MAGNETIC WATER EFFECTS ON GROWTH AND SOME PHYSIOLOGICAL CHARACTERISTICS OF PAULOWNIA TOMENTOSA THUNB UNDER CADMIUM STRESS CONDITIONS

Paulownia (Paulownia tomentosa) is considered as one of the world's fastest-growing species of trees and most widely used for commercial. This research was done as a factorial experiment in Koya city, Erbil, Iraq during 2021-2022 to study the effects of magnetic water (MW) at (0, 500,1000, 1500 and 2000) gauss and cadmium chloride (Cd) at (0, 3.33, 6.66 and 10 mg Kg-1soil) on some growth, physiological and biochemical properties of this plant. Results demonstrate that MW had non-significant differ regarding the survived and the velocity of cutting outgrowth compare to using tap water, whereas Cd application increased the velocity of cutting outgrowth. At least one of MW powers increased significantly each of plant leaf-area, stem diameter, shoot and root fresh weight and dry matter content, as well as all Cd concentrations increased the plants leaves number, leaf-area, stem diameter. Cd had more effects on roots than plant shoots, where it has non-significant effects on shoot high or dry matter, whereas it increased each of shoot and root fresh weight significantly compared to the control treatment. Low power MW (500 and 1000) gauss performed better than high powers (1500 and 2000) gauss in increasing the content of photosynthesis pigments. Utilizing magnetic water greatly enhanced total carotenoids and chlorophyll a, b, regardless to device power. Chlorophyll (a and b) were both significantly reduced by high Cd concentrations; however it was significantly increased at low concentrations as compared to other treatments. High power MW decreased significantly peroxidase enzyme activity and proline content whereas it decreased the percent of total carbohydrate compared to other treatments. Cd application decreased each of peroxidase enzyme activity, percent of total carbohydrate content, increased ascorbic acid and proline significantly in comparing to the control.