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Background: Drought stress is a significant abiotic stressor that hinders growth, development, and crop yield in soybeans. Strigolactones (SLs) positively regulate plant resistance to drought stress. However, the impact of foliar application of SLs having different concentrations on soybean growth and metabolic pathways related to osmoregulation remains unknown. Therefore, to clarify the impact of SLs on soybean root growth and cellular osmoregulation under drought stress, we initially identified optimal concentrations and assessed key leaf and root indices. Furthermore, we conducted transcriptomic and metabolic analyses to identify differential metabolites and up-regulated genes. Results: The results demonstrated that drought stress had a significant impact on soybean biomass, root length, root surface area, water content and photosynthetic parameters. However, when SLs were applied through foliar application at appropriate concentrations, the accumulation of ABA and soluble protein increased, which enhanced drought tolerance of soybean seedlings by regulating osmotic balance, protecting membrane integrity, photosynthesis and activating ROS scavenging system. This also led to an increase in soybean root length, lateral root number and root surface area. Furthermore, the effects of different concentrations of SLs on soybean leaves and roots were found to be time-sensitive. However, the application of 0.5 µM SLs had the greatest beneficial impact on soybean growth and root morphogenesis under drought stress. A total of 368 differential metabolites were screened in drought and drought plus SLs treatments. The up-regulated genes were mainly involved in nitrogen compound utilization, and the down-regulated metabolic pathways were mainly involved in maintaining cellular osmoregulation and antioxidant defenses. Conclusions: SLs enhance osmoregulation in soybean plants under drought stress by regulating key metabolic pathways including Arachidonic acid metabolism, Glycerophospholipid metabolism, Linoleic acid metabolism, and Flavone and flavonol biosynthesis. This study contributes to the theoretical understanding of improving soybean adaptability and survival in response to drought stress. [ABSTRACT FROM AUTHOR]

Abstract Background Drought stress is a significant abiotic stressor that hinders growth, development, and crop yield in soybeans. Strigolactones (SLs) positively regulate plant resistance to drought stress. However, the impact of foliar application of SLs having different concentrations on soybean growth and metabolic pathways related to osmoregulation remains unknown. Therefore, to clarify the impact of SLs on soybean root growth and cellular osmoregulation under drought stress, we initially identified optimal concentrations and assessed key leaf and root indices. Furthermore, we conducted transcriptomic and metabolic analyses to identify differential metabolites and up-regulated genes. Results The results demonstrated that drought stress had a significant impact on soybean biomass, root length, root surface area, water content and photosynthetic parameters. However, when SLs were applied through foliar application at appropriate concentrations, the accumulation of ABA and soluble protein increased, which enhanced drought tolerance of soybean seedlings by regulating osmotic balance, protecting membrane integrity, photosynthesis and activating ROS scavenging system. This also led to an increase in soybean root length, lateral root number and root surface area. Furthermore, the effects of different concentrations of SLs on soybean leaves and roots were found to be time-sensitive. However, the application of 0.5 µM SLs had the greatest beneficial impact on soybean growth and root morphogenesis under drought stress. A total of 368 differential metabolites were screened in drought and drought plus SLs treatments. The up-regulated genes were mainly involved in nitrogen compound utilization, and the down-regulated metabolic pathways were mainly involved in maintaining cellular osmoregulation and antioxidant defenses. Conclusions SLs enhance osmoregulation in soybean plants under drought stress by regulating key metabolic pathways including Arachidonic acid metabolism, Glycerophospholipid metabolism, Linoleic acid metabolism, and Flavone and flavonol biosynthesis. This study contributes to the theoretical understanding of improving soybean adaptability and survival in response to drought stress.

In this study, we investigated if reducing the amount of chemical fertilizer by combining it with organic fertilizer in Hemerocallis citrina Baroni (H. citrina) cultivation could improve plant growth and photosynthetic capacity and, consequently, increase yield and quality. A continuous two-year field experiment was conducted at a research farm in Zhangzhou City, China, during 2021–2022. Six fertilization levels with two locally grown H. citrina cultivars, "Taidong 6" and "Shibage", were tested. The results showed that 100% of the recommended dose of chemical fertilizer (RDF) with bio-organic fertilizer yielded superior effects in promoting both vegetative and reproductive growth in comparison to RDF alone. However, reducing the application rate of chemical fertilizers, especially by more than 40%, resulted in a significant decline in certain agronomic traits such as plant width, leaf width, and scape length. Compared to RDF, the use of 100% or 80% RDF in combination with bio-organic fertilizer significantly increased chlorophyll content, net photosynthetic rate, and transpiration rate as well as yield production, while excessive reductions in chemical fertilizer rate produced results that demonstrated an opposite trend. The co-application of chemical and bio-organic fertilizer enhanced the contents of soluble sugar and lowered total acidity, whereas excessive chemical fertilizer reduction decreased vitamin C, total flavonoids, and soluble protein levels. Utilizing radar chart analysis for a comprehensive assessment of yield and quality demonstrates that the application of bio-organic fertilizer with 80% RDF could be a better field fertilization regime for H. citrina cultivation. [ABSTRACT FROM AUTHOR]

A factorial design consisting of four N treatments (no N fertilization, 0.70, 0.14, and 0.28 mol N·plant−1) combined with two water conditions, drought (D = 25 ± 5% soil moisture content) and well-watered (W = 65 ± 5% soil moisture content), was used. Overall, the gas exchange parameters, chlorophyll, and growth of T. sinensis seedlings were significantly inhibited under drought conditions, while all of them showed improvement with N fertilizer, particularly at 0.14~0.28 mol N·plant−1. Under drought conditions, the root length and root surface area of T. sinensis increased; N application positively influenced the above root morphological changes. The activities of antioxidant enzymes such as superoxide dismutase (SOD; EC1.15.1.1) and peroxidase (POD; EC1.11.1.7) and the contents of osmotic adjustment substances such as soluble sugar and proline increased upon drought stress, but decreased under N application conditions. Overall, T. sinensis responds to drought stress through the synergistic action of drought resistance and drought tolerance mechanisms. N application enhances photosynthesis and improves root morphology, compensating for the need for osmotic regulation and reactive oxygen species scavenging. [ABSTRACT FROM AUTHOR]

Introduction: In the Near East and North Africa (NENA) region, crop production is being affected by various abiotic factors, including freshwater scarcity, climate, and soil salinity. As a result, farmers in this region are in search of salt-tolerant crops that can thrive in these harsh environments, using poor-quality groundwater. The main staple food crop for most of the countries in this region, Tunisia included, is barley. Methods: The present study was designed to investigate the sensitivity and tolerance of six distinct barley genotypes to aridity and salinity stresses in five different natural field environments by measuring their photosynthetic activity. Results and discussion: The results revealed that tolerant genotypes were significantly less affected by these stress factors than sensitive genotypes. The genotypes that were more susceptible to salinity and aridity stress exhibited a significant decline in their photosynthetic activity. Additionally, the fluorescence yields in growth phases J, I, and P declined significantly in the order of humid environment (BEJ), semi-arid site (KAI), and arid environment (MED) and became more significant when salt stress was added through the use of saline water for irrigation. The stress adversely affected the quantum yield of primary photochemistry (jP0), the quantum yield of electron transport (jE0), and the efficiency by trapped excitation (y0) in the vulnerable barley genotypes. Moreover, the performance index (PI) of the photosystem II (PSII) was found to be the most distinguishing parameter among the genotypes tested. The PI of sensitive genotypes was adversely affected by aridity and salinity. The PI of ICARDA20 and Konouz decreased by approximately 18% and 33%, respectively, when irrigated with non-saline water. The reduction was even greater, reaching 39%, for both genotypes when irrigated with saline water. However, tolerant genotypes Souihli and Batini 100/1B were less impacted by these stress factors. The fluorescence study provided insights into the photosynthetic apparatus of barley genotypes under stress. It enabled reliable salinity tolerance screening. Furthermore, the study confirmed that the chlorophyll a fluorescence induction curve had an inflection point (step K) even before the onset of visible signs of stress, indicating physiological disturbances, making chlorophyll fluorescence an effective tool for identifying salinity tolerance in barley. [ABSTRACT FROM AUTHOR]

Phytoplankton are photosynthetic microscopic organisms that inhabit the upper sunlit layer (euphotic zone) of marine and fresh water bodies. Phytoplankton, as the primary producer of the aquatic ecosystem’s food chain and are very sensitive to environmental changes as energy stored up in them determine the basic primary productivity of an ecosystem. There is dearth of information on the phytoplankton community of the Festac creek and thus the need for this study which aims at microscopically investigating the phytoplankton community of the Festac creek. The Phytoplankton diversity and distribution of the Festac creek, Lagos, Nigeria. was investigated for 12 months (November 2021 – October, 2022). Phytoplankton samples were collected monthly for 12 months, using a 55 μm mesh size standard plankton net towed horizontally from a motorized boat for 5 mins at < 4 Km/h and preserved by adding 4% unbuffered formalin. The drop count microscopic analysis method was used to study the phytoplankton species. A total of 34 phytoplankton species from 7 algal classes namely Bacillariophyceae (16 species), Cyanophyceae (9 species), Chlorophyceae (2 species), Conjugatophyceae (3 species), Dictyochophyceae (2 species), Tintinnid (1 species) and Dinophyceae (1 species) were recorded. Notable species were recorded such as: Lyngbya sp, Prorocentrum lima, Navicula sp. Nitzschia lineola, Phormidium bohneri, Oscillatoria limosa, Oscillatoria nigro viridis, Oscillatoria formosa and some other known marine species such as Coscinodiscus radiatus, Coscinodiscus marginatus Skeletonema costatum, Odontella sinensis, Thalassionema nizschoides, Fragillaria oceanica, Spirulina subsalsa and Tintinnopsis radix. The most abundant class was the Cyanophyceae (Blue-green algae) with Oscillatoria limosa being the most abundant species. This could be attributed to the constant addition of nutrient particularly nitrate and phosphate run offs from industries around the study area which enhances cyanobacterial growth and indicates that the Festac creek is eutrophic. [ABSTRACT FROM AUTHOR]

Shallots are essential vegetables in horticulture, but there is insufficient information available on the effects of drought stress on different growth stages and the inoculation of plant growth-promoting rhizobacteria (PGPR) on their photosynthetic characteristics. This study aims to investigate the effects of drought stress at different growth stages (vegetative growth phase, bulb initiation phase, bulb development phase, and maturation phase) and PGPR inoculation (Pseudomonas Pb04 and Bacillus Pb03) to mitigate the negative impact of drought stress on photosynthetic characteristics, chlorophyll content, and shallot yield. The results showed that the optimal photosynthesis rate, chlorophyll content, and yield of shallots were most tolerant when the plants experienced drought stress in the maturation phase compared to other growth phases. During the maturation phase, the reduction in photosynthesis rate at PPFD 900 µmol.m-2.s-1 is only 19.1% compared to plants without drought stress. Drought stress during the bulb growth phase takes the longest to recover conditions after stress, leading to inhibited growth when stress occurs during this phase. In the bulb growth phase, the decrease in photosynthesis rate is 34.8% compared to the treatment without drought stress. PGPR can mitigate the sensitivity of plants to drought stress. Pseudomonas Pb04 predominantly suppresses the impact of drought stress during the vegetative growth phase, while Bacillus Pb03 has a more dominant effect on drought stress occurring during bulb initiation, bulb development, and maturation phases.

Shallots are essential vegetables in horticulture, but there is insufficient information available on the effects of drought stress on different growth stages and the inoculation of plant growth-promoting rhizobacteria (PGPR) on their photosynthetic characteristics. This study aims to investigate the effects of drought stress at different growth stages (vegetative growth phase, bulb initiation phase, bulb development phase, and maturation phase) and PGPR inoculation (Pseudomonas Pb04 and Bacillus Pb03) to mitigate the negative impact of drought stress on photosynthetic characteristics, chlorophyll content, and shallot yield. The results showed that the optimal photosynthesis rate, chlorophyll content, and yield of shallots were most tolerant when the plants experienced drought stress in the maturation phase compared to other growth phases. During the maturation phase, the reduction in photosynthesis rate at PPFD 900 µmol·m-2s-1 is only 19.1% compared to plants without drought stress. Drought stress during the bulb growth phase takes the longest to recover conditions after stress, leading to inhibited growth when stress occurs during this phase. In the bulb growth phase, the decrease in photosynthesis rate is 34.8% compared to the treatment without drought stress. PGPR can mitigate the sensitivity of plants to drought stress. Pseudomonas Pb04 predominantly suppresses the impact of drought stress during the vegetative growth phase, while Bacillus Pb03 has a more dominant effect on drought stress occurring during bulb initiation, bulb development, and maturation phases. [ABSTRACT FROM AUTHOR]

Stomata are microscopic pores at the surface of plant leaves that facilitate gaseous diffusion to support photosynthesis. The guard cells around each stoma regulate the pore aperture. Plants that carry out C4 photosynthesis are usually more resilient than C3 plants to stress, and their stomata operate over a lower dynamic range of CO2 within the leaf. What makes guard cells of C4 plants more responsive than those of C3 plants? We used gas exchange and electrophysiology, comparing stomatal kinetics of the C4 plant Gynandropsis gynandra and the phylogenetically related C3 plant Arabidopsis thaliana. We found, with varying CO2 and light, that Gynandropsis showed faster changes in stomata conductance and greater water use efficiency when compared with Arabidopsis. Electrophysiological analysis of the dominant K+ channels showed that the outward‐rectifying channels, responsible for K+ loss during stomatal closing, were characterised by a greater maximum conductance and substantial negative shift in the voltage dependence of gating, indicating a reduced inhibition by extracellular K+ and enhanced capacity for K+ flux. These differences correlated with the accelerated stomata kinetics of Gynandropsis, suggesting that subtle changes in the biophysical properties of a key transporter may prove a target for future efforts to engineer C4 stomatal kinetics. Summary Statement: Compared with Arabidopsis, the outward‐rectifying K+ channels in guard cells of the C4 plant Gynandropsis gynandra incorporate gating that is displaced to favour enhanced K+ efflux and promote K+ influx. These characteristics are likely to underpin the faster stomatal that are observed in the C4 plant. [ABSTRACT FROM AUTHOR]

Melatonin can improve plant adaptability to water deficit stress by regulating the biosynthesis of flavonoids and improving the reactive oxygen species-scavenging enzyme system. However, it remains unclear whether melatonin mitigates the effects and causes of water deficit stress in Cenchrus alopecuroides. We conducted a PEG-simulated water stress pot experiment to determine whether and how exogenous melatonin alleviates water deficit in C. alopecuroides. The experiment was divided into four treatments: (1) normal watering (Control), (2) 40% PEG-6000 treatment (D), (3) 100 μmol·L−1 melatonin treatment (MT), and (4) both melatonin and PEG-6000 treatment (DMT). The results showed that melatonin can alleviate water deficit in C. alopecuroides by effectively inhibiting plant chlorophyll degradation and MDA accumulation while increasing antioxidant enzyme activities and photosynthetic rates under water deficit stress. The transcriptome results indicated that melatonin regulates the expression of genes with the biosynthesis pathway of flavonoids (by increasing the expression of PAL, 4CL, HCT, and CHS), photosynthesis-antenna proteins (by increasing the expression of LHC), and sulfur metabolism (the expression of PAPSS and CysC is up-regulated in the assimilatory sulfate reduction pathway), while up-regulating the transcription factors (AP2/ERF-ERF-, C2H2-, WRKY-, Tify-, bHLH-, NAC-, and MYB-related). These findings revealed the possible causes by which melatonin mitigates water deficit stress in C. alopecuroides, which provided novel insights into the role of melatonin in water deficit stress. [ABSTRACT FROM AUTHOR]

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In China, cadmium (Cd) stress has a significant role in limiting the development and productivity of purple flowering stalks (Brassica campestris var. purpuraria). Exogenous selenium supplementation has been demonstrated in earlier research to mitigate the effects of Cd stress in a range of plant species; nevertheless, the physiological and molecular processes by which exogenous selenium increases vegetable shoots' resistance to Cd stress remain unclear. Purple flowering stalks (Brassica campestris var. purpuraria) were chosen as the study subject to examine the effects of treatment with sodium selenite (Na2SeO3) on the physiology and transcriptome alterations of cadmium stress. Purple flowering stalk leaves treated with exogenous selenium had higher glutathione content, photosynthetic capacity, and antioxidant enzyme activities compared to the leaves treated with Cd stress alone. Conversely, the contents of proline, soluble proteins, soluble sugars, malondialdehyde, and intercellular CO2 concentration tended to decrease. Transcriptome analysis revealed that 2643 differentially expressed genes (DEGs) were implicated in the response of exogenous selenium treatment to Cd stress. The metabolic pathways associated with flavonoid production, carotenoid synthesis, glutathione metabolism, and glucosinolate biosynthesis were among those enriched in these differentially expressed genes. Furthermore, we discovered DEGs connected to the production route of glucosinolates. This work sheds fresh light on how purple flowering stalks' tolerance to cadmium stress is improved by exogenous selenium. [ABSTRACT FROM AUTHOR]

Sustainable practices in plant production involve various environmental methods that improve the urban ecosystem by preserving both natural resources and biological diversity. Organic material application against salt stress is one of the most important sustainable practices. The purpose of this study was to explore how various traits of Lavandula officinalis under salt stress were affected by seaweed liquid. To this end, the experiment was performed as a completely randomized experimental design with two factors including four replications under greenhouse conditions. In the experiments, salt concentrations were prepared as control (distilled water), 40 mM and 80 mM NaCl, and seaweed liquid levels were applied as control (0%) – 0.5%—1%—2% and 4%. L. officinalis was considerably negatively affected by salt stress in terms of its quality, growth, photosynthetic and biochemical traits. According to the results of this empirical research, seaweed liquid application was the alleviating factor in negative effects in all traits resulting from the increase in NaCl concentrations. Seaweed liquid also revealed the highest values of all traits in the absence of salt stress. Photosynthetic and biochemical traits without proline, Relative water content, and chlorophyll a/b declined more than other quality and growth traits with a rise in salt content from 0 to 40 mM. Further research will be needed to test the beneficial effects of seaweed liquid on traits of L. officinalis seedlings in outdoor landscaping that includes salty spaces. [ABSTRACT FROM AUTHOR]

Key message: Significant improvement in salt tolerance of poplar hybrids with different salt 2 tolerant varieties. Salt stress is a global environmental factor that limits plant growth and productivity. Poplar has the characteristics of fast growth and fine texture, and the adaptability of hybrid plants to environmental stress is better than that of their parents. In this study, Populus simonii 'CAFDF' (♀), P. nigra 'CAFDM' (♂), P. simonii × P. nigra CV. 'CAFDS2' (DS2), and Populus simonii × P. nigra CV. 'CAFDS3' (DS3) were used to reveal the response and adaptation mechanism of the photosynthetic function of hybrid poplar leaves to salt stress by physiological combined with transcriptome technology. The results showed that NaCl stress significantly reduced the chlorophyll content of the leaves of both parents, but the reduction of chlorophyll in hybrid offspring under salt stress was lower than that in parents. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of differentially expressed genes (DEGs) in both hybrid plants and biparental progenies under NaCl stress was enriched for photosynthesis-antenna proteins, photosynthesis, and carbon fixation in photosynthetic organisms. Under salt stress treatment, the ability of leaves in DS2 and DS3 plants to capture solar energy and transfer their excitement energy to the reaction center were higher than that of their parental plants. NaCl stress caused damage to photosystem II (PSII) and photosystem I (PSI) in poplar leaves, and their activities decreased. The hybrid offspring improved the integrity of PSII receptor side electron transfer and donor side oxygen-evolving complex (OEC) compared with the two parents. The expression of other coding genes of the PSII reaction center, as well as coding genes for PSI reaction center and ATP synthetase in the hybrid offspring under NaCl stress are higher than that of the parents, which reduces damage to the electron transfer chain and the energy supply required for maintaining plant growth and development. The cyclic electron flow dependent on PGR5 and NDH pathways (PGR5-CEF and NDH-CEF) of hybrids and female parents were significantly higher than those of male parents. Hybrid progeny and the maternal parent alleviated the damage of salt stress on PSII and PSI by promoting CEF. The hybrid plants protect the photosynthetic apparatus by regulating energy dissipation, while the PSII of the parents plants was damaged due to serious photooxidation. Under salt stress, the net photosynthetic rate (Pn) in hybrid plants increased, and the non-stomatal factors, which was also confirmed by the Calvin cycle. [ABSTRACT FROM AUTHOR]

[Objective] This study investigated the effects of different phosphorus supply levels on photosynthetic characteristics and mineral element absorption of green pepper seedlings to provide basis for further improving precise fertilization and high-quality production of green pepper. [Method] The experiment was carried out by hydroponic method with green pepper seedlings of Audrey Red Silk spear. Four treatments of T1(50% P), T2(75% P), T3(100% P), T4(125% P) were included and biomass, root activity, photosynthetic pigment content, photosynthetic characteristics, mineral element content and accumulation of green pepper seedlings were measured. Then, the effects on growth characteristics of green pepper seedlings were analyzed and the comprehensive performance was evaluated using principal component analysis. [Result] Compared to T3, fresh quality of root, dry quality of root, root activity, chlorophyll a, carotenoid, chlorophyll a+b, net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of grafted green pepper seedlings in T1 treatment were significantly decreased by 35.03%, 33.33%, 4.32%, 38.65%, 61.83%, 22.01%, 50.48%, 36.50% and 40.16%, while intercellular CO2 concentration (Ci) was increased significantly by 18.43%. In T2 treatment, fresh quality of shoot, dry quality of shoot, root activity, chlorophyll b, Tr and Gs were significantly increased by 51.76%, 54.02%, 14.76%, 40.49%, 2.02% and 124.76%, respectively. In T4 treatment, fresh quality of root, dry quality of root, root activity, hlorophyll a and Pn were significantly decreased by 26.60%, 32.00%, 17.87 %, 9.81 % and 28.83%, respectively. Compared with T3, the accumulation of Fe, Zn, Ca, K, Mg and N in T2 was increased significanty by 62.67%, 44.56 %, 42.33%, 24.00%, 33.97% and 41.41 %, while that of Mn and P was decreased sigificantly by 20.85% and 34.99%, respectively. The principal component analysis showed that the comprehensive performance of green pepper seedlings was in the order of T2>T3>T4> T1. [Conclusion] The application of 75% phosphorus fertilizer (T2) had good effects on growth, photosynthesis and mineral element absorption of green pepper seedlings. [ABSTRACT FROM AUTHOR]

Terrestrial LiDAR has emerged as a promising technology for accurate forest assessment. LiDAR can provide a 3D image composed of a cloud of points using a rotary laser scanner. The point cloud data (PCD) contain information on the (x, y, z) coordinates of every single scanned point and a raw intensity parameter. This study introduces an algorithm for the automatic and accurate separation of the photosynthetic features of a PCD. It is shown that the recorded raw intensity is not a suitable parameter for the separation of photosynthetic features. Instead, for the first time, the absorption intensity is developed for every point based on its raw intensity and distance from the scanner, using proper scaling functions. Then, the absorption intensity is utilized as the only criterion for the classification of the points between photosynthetic and non-photosynthetic features. The proposed method is applied to the scans from a Canadian Boreal Forest and successfully extracted the photosynthetic features with minimal average type I and type II error rates of 5.7% and 4.8%. The extracted photosynthetic PCD can be readily used for calculating important forest parameters such as the leaf area index (LAI) and the green biomass. In addition, it can be used for estimating forest carbon storage and monitoring temporal changes in vegetation structure and ecosystem health. [ABSTRACT FROM AUTHOR]

There is a problem of vegetable protein deficiency for feed, processing and nutrition in many countries: to produce or import? White lupin cultivation in Russia is important due its high potential seed and protein yield. The breeding program for creating cultivars of white lupin with a determinant type of growth and the study of the dynamic parameters of the yield formation was carried out in many years of research in the northern part of the Central-Chernozem region of Russia. Experiments were conducted at the experimental field in Tambov region. Cultivar is one of the main components of resource-saving technologies. For the first time in Russia, under these conditions, cultivars of white lupin with a determinant type of growth were created. Among them are Start, Gamma, Delta, Dega, Deter1, Timiryazevskiy with different plant architectonics. Care adapted to the conditions of the region, ripen steadily, and grain yield of 3-5 ton ha-1. Agrocenosis is a photosynthetic system functions from emergence to beginning of maturity including four biologically distinct periods of crop formation: I- emergence - the beginning of flowering; II- flowering and pod formation; III- pod growth; and IV- seed filling. The length of the periods and the dynamic parameters of the yield formation of white lupin for each period were determined. Among the parameters were the leaf area index (LAI), the total dry matter accumulation (TDM), the crop growth rate (CGR), leaf area duration (LAD), net assimilation rate (NAR), and yield components. Period II was critical in yield formation. Variability of parameters was determined in connection with weather conditions and seed yield. The conducted studies made it possible for white lupin cultivars with determinant type of growth to find out dynamic pattern of yield formation and to estimate the degree of effect of weather conditions on dynamic parameters and seed productivity. [ABSTRACT FROM AUTHOR]

IntroductionIn the Near East and North Africa (NENA) region, crop production is being affected by various abiotic factors, including freshwater scarcity, climate, and soil salinity. As a result, farmers in this region are in search of salt-tolerant crops that can thrive in these harsh environments, using poor-quality groundwater. The main staple food crop for most of the countries in this region, Tunisia included, is barley.MethodsThe present study was designed to investigate the sensitivity and tolerance of six distinct barley genotypes to aridity and salinity stresses in five different natural field environments by measuring their photosynthetic activity.Results and discussionThe results revealed that tolerant genotypes were significantly less affected by these stress factors than sensitive genotypes. The genotypes that were more susceptible to salinity and aridity stress exhibited a significant decline in their photosynthetic activity. Additionally, the fluorescence yields in growth phases J, I, and P declined significantly in the order of humid environment (BEJ), semi-arid site (KAI), and arid environment (MED) and became more significant when salt stress was added through the use of saline water for irrigation. The stress adversely affected the quantum yield of primary photochemistry (φP0), the quantum yield of electron transport (φE0), and the efficiency by trapped excitation (ψ0) in the vulnerable barley genotypes. Moreover, the performance index (PI) of the photosystem II (PSII) was found to be the most distinguishing parameter among the genotypes tested. The PI of sensitive genotypes was adversely affected by aridity and salinity. The PI of ICARDA20 and Konouz decreased by approximately 18% and 33%, respectively, when irrigated with non-saline water. The reduction was even greater, reaching 39%, for both genotypes when irrigated with saline water. However, tolerant genotypes Souihli and Batini 100/1B were less impacted by these stress factors.The fluorescence study provided insights into the photosynthetic apparatus of barley genotypes under stress. It enabled reliable salinity tolerance screening. Furthermore, the study confirmed that the chlorophyll a fluorescence induction curve had an inflection point (step K) even before the onset of visible signs of stress, indicating physiological disturbances, making chlorophyll fluorescence an effective tool for identifying salinity tolerance in barley.

Among the oil-seed crops, Sesamum indicum L. is an important nutritionally rich crop, well adapted to grow in semi-arid regions. Waterlogging stress adversely affects the growth of sesame by limiting diffused oxygen availability in soil and generating hypoxic, subsequently anoxic conditions. The present study aimed to screen the 1,006 accessions for waterlogging stress response at the seedling stage to identify the most tolerant and susceptible genotype. The investigation revealed that, 48 h of stress are detrimental and 10 days post-waterlogging impede crop survival. The screened accessions were narrowed down by 8 to detect the morphological alterations, and the morphological characteristics such as shoot height, root length, SPAD, branches per plant and relative water content r) were significantly higher in check and EC377024. Enzymatic (SOD, CAT and APX) and non-enzymatic (TFC, TPC, DPPH, FRAP, TAA, MDA and proline) antioxidant activity was notably higher in check and EC377024 and lower in IC129289. DAB and NBT assay confirmed lower damages from free radicals in EC377024 compared to IC129289. Moreover, contrasting gene expression profiling of free radicals (POD and RBOHC), carbohydrate metabolism (SuSy2 and StSy1), phosphate group gene (PSRG), and plant hormone (ERF RAP 2–7, ACC) confirmed the tolerance in EC377024 under waterlogging stress conditions. Besides, metabolomics study in EC377024 at control and 48 h of waterlogging stress indicate the significant accumulated metabolites in fatty acid (decanoate), carbohydrate, amino acid, Shikimate, MEP (5-enolpyruvoyl-shikimate-3-phosphate) Krebs cycle and Xanthophyll pathways. This comprehensive combination of morpho-physiological, biochemical, molecular and metabolomic characterizations highlight the stress responsive mechanisms between the tolerant (EC377024) and susceptible (IC129289) genotypes.

The proteome analysis of winter crops during cold acclimation and overwintering can provide important information for designing breeding processes. The current experiment was carried out to investigate the proteome changes in frost-tolerant winter wheat (cv. Norstar) during different cold acclimation (CA) periods under field conditions in a cold and high-altitude region by two-dimensional gel-based proteomic techniques. The results showed that frost tolerance significantly increased by CA and the lethal freezing temperatures (LT50) 10, 14, and 18 weeks after seed sowing were -28°C, -22°C, and -10°C, respectively. By the beginning of the reproductive stage (double ridge stage), the LT50 values had decreased significantly. Around 1000 protein spots were distinguished by Coomassie staining on the gels. The changes in the proteins during the CA often occurred in those with a functional role in photosynthesis, energy production (glycolysis), transcription, chaperone-like activities, membrane and cytoskeleton reorganisation, transport, redox adjustments, and signalling. The results revealed that changes in chloroplast proteins, certain transcription factors such as MADS-box transcription factor 26, and antioxidant enzymes (ascorbate peroxidase) show a similar trend to freezing tolerance, and their expression decreases with the onset of reproductive growth and the loss of freezing tolerance. During the acclimation period, most of the changes were focused on defence systems and cytoskeleton rearrangement, while, photosynthesis, and energy production became the main priority at the beginning of reproductive growth.

Abstract Background In the context of climate change, maize is facing unprecedented heat stress (HS) threats during grain filling. Understanding how HS affects yield is the key to reducing the impact of climate change on maize production. Suyunuo5 (SYN5) and Yunuo7 (YN7) were used as materials, and four temperature gradients of 28℃ (day)/20℃ (night; T0, control), 32 °C/24°C (T1, mild HS), 36 °C/28°C (T2, moderate HS), and 40 °C/32°C (T3, severe HS) were set up during grain filling to explore the physiological mechanism of different degrees HS affecting photosynthetic characteristics of leaves in this study. Results Results showed that HS accelerated the degradation of chlorophyll, disturbed the metabolism of reactive oxygen species, reduced the activity of antioxidant enzymes, and caused leaf damage. Heat stress induced the down-regulation of photosynthesis-related genes, which results in the decrease of enzymatic activities involved in photosynthesis, thereby inhibiting photosynthesis and reducing yield. Integrated analysis showed that the degree of the negative influence of three HS types during grain filling on leaves and yield was T3 > T2 > T1. The increase in HS disturbed leaf physiological activities and grain filling. Meanwhile, this study observed that the YN7 was more heat tolerance than SYN5 and thus it was recommended to use YN7 in waxy maize planting areas with frequent high temperatures. Conclusions Heat stress during grain filling caused premature senescence of the leaves by inhibiting the ability of leaves to photosynthesize and accelerating the oxidative damage of cells, thereby affecting the waxy maize yield. Our study helped to simulate the productivity of waxy maize under high temperatures and provided assistance for a stable yield of waxy maize under future climate warming.

A factorial design consisting of four N treatments (no N fertilization, 0.70, 0.14, and 0.28 mol N·plant−1) combined with two water conditions, drought (D = 25 ± 5% soil moisture content) and well-watered (W = 65 ± 5% soil moisture content), was used. Overall, the gas exchange parameters, chlorophyll, and growth of T. sinensis seedlings were significantly inhibited under drought conditions, while all of them showed improvement with N fertilizer, particularly at 0.14~0.28 mol N·plant−1. Under drought conditions, the root length and root surface area of T. sinensis increased; N application positively influenced the above root morphological changes. The activities of antioxidant enzymes such as superoxide dismutase (SOD; EC1.15.1.1) and peroxidase (POD; EC1.11.1.7) and the contents of osmotic adjustment substances such as soluble sugar and proline increased upon drought stress, but decreased under N application conditions. Overall, T. sinensis responds to drought stress through the synergistic action of drought resistance and drought tolerance mechanisms. N application enhances photosynthesis and improves root morphology, compensating for the need for osmotic regulation and reactive oxygen species scavenging.

In this study, we investigated if reducing the amount of chemical fertilizer by combining it with organic fertilizer in Hemerocallis citrina Baroni (H. citrina) cultivation could improve plant growth and photosynthetic capacity and, consequently, increase yield and quality. A continuous two-year field experiment was conducted at a research farm in Zhangzhou City, China, during 2021–2022. Six fertilization levels with two locally grown H. citrina cultivars, “Taidong 6” and “Shibage”, were tested. The results showed that 100% of the recommended dose of chemical fertilizer (RDF) with bio-organic fertilizer yielded superior effects in promoting both vegetative and reproductive growth in comparison to RDF alone. However, reducing the application rate of chemical fertilizers, especially by more than 40%, resulted in a significant decline in certain agronomic traits such as plant width, leaf width, and scape length. Compared to RDF, the use of 100% or 80% RDF in combination with bio-organic fertilizer significantly increased chlorophyll content, net photosynthetic rate, and transpiration rate as well as yield production, while excessive reductions in chemical fertilizer rate produced results that demonstrated an opposite trend. The co-application of chemical and bio-organic fertilizer enhanced the contents of soluble sugar and lowered total acidity, whereas excessive chemical fertilizer reduction decreased vitamin C, total flavonoids, and soluble protein levels. Utilizing radar chart analysis for a comprehensive assessment of yield and quality demonstrates that the application of bio-organic fertilizer with 80% RDF could be a better field fertilization regime for H. citrina cultivation.

Yellow horn grows in northern China and has a high tolerance to drought and poor soil. Improving photosynthetic efficiency and increasing plant growth and yield under drought conditions have become important research content for researchers worldwide. Our study goal is to provide comprehensive information on photosynthesis and some candidate genes breeding of yellow horn under drought stress. In this study, seedlings’ stomatal conductance, chlorophyll content, and fluorescence parameters decreased under drought stress, but non-photochemical quenching increased. The leaf microstructure showed that stomata underwent a process from opening to closing, guard cells from complete to dry, and surrounding leaf cells from smooth to severe shrinkage. The chloroplast ultrastructure showed that the changes of starch granules were different under different drought stress, while plastoglobules increased and expanded continuously. In addition, we found some differentially expressed genes related to photosystem, electron transport component, oxidative phosphate ATPase, stomatal closure, and chloroplast ultrastructure. These results laid a foundation for further genetic improvement and deficit resistance breeding of yellow horn under drought stress.

Oxygen as one of the most critical substances in living organisms has attracted ever‐increasing attention in disease treatment, which is important in regulating metabolic activities. However, the hypoxia arising from disease is a prevalent problem, leading to observably reduced therapeutic effectiveness in photodynamic therapy, radiotherapy, sonodynamic therapy, etc. Therefore, the reversion of hypoxia becomes the basis for enhancing the disease treatment. Thanks to the development of nanotechnology, various nanomaterials with oxygen‐production capacity are explored to recover the function of oxygen in tissue, but there are still some limitations. The photosynthetic microorganisms (PSMs) are extensively applied for improving hypoxia in diseases due to their highly efficient photocatalytic oxygen production efficacy and desirable biocompatibility. In this review, the up‐to‐date research progress on therapeutic modalities of microbial‐based photosynthetic oxygenation (e.g., cancer treatment, wound healing, and tissue engineering) are summarized and highlighted. In addition, the key issue of biocompatibility/biosafety of microbial‐based treatment that is fundamental to apply in vivo is further emphasized and clarified. Finally, the present critical issues are discussed and the future evolution of microbial‐based treatment based on photosynthetic oxygenation is predicted, promoting further development and clinical applications. [ABSTRACT FROM AUTHOR]

Background: In the context of climate change, maize is facing unprecedented heat stress (HS) threats during grain filling. Understanding how HS affects yield is the key to reducing the impact of climate change on maize production. Suyunuo5 (SYN5) and Yunuo7 (YN7) were used as materials, and four temperature gradients of 28℃ (day)/20℃ (night; T0, control), 32 °C/24°C (T1, mild HS), 36 °C/28°C (T2, moderate HS), and 40 °C/32°C (T3, severe HS) were set up during grain filling to explore the physiological mechanism of different degrees HS affecting photosynthetic characteristics of leaves in this study. Results: Results showed that HS accelerated the degradation of chlorophyll, disturbed the metabolism of reactive oxygen species, reduced the activity of antioxidant enzymes, and caused leaf damage. Heat stress induced the down-regulation of photosynthesis-related genes, which results in the decrease of enzymatic activities involved in photosynthesis, thereby inhibiting photosynthesis and reducing yield. Integrated analysis showed that the degree of the negative influence of three HS types during grain filling on leaves and yield was T3 > T2 > T1. The increase in HS disturbed leaf physiological activities and grain filling. Meanwhile, this study observed that the YN7 was more heat tolerance than SYN5 and thus it was recommended to use YN7 in waxy maize planting areas with frequent high temperatures. Conclusions: Heat stress during grain filling caused premature senescence of the leaves by inhibiting the ability of leaves to photosynthesize and accelerating the oxidative damage of cells, thereby affecting the waxy maize yield. Our study helped to simulate the productivity of waxy maize under high temperatures and provided assistance for a stable yield of waxy maize under future climate warming. [ABSTRACT FROM AUTHOR]

The concentrations of exogenous nitrogen and calcium can significantly regulate plant growth and photosynthesis and mutually affect their absorption and utilization. However, whether there is an optimal nitrogen–calcium ratio (N:Ca ratio) in poplar seedling growth and physiological adaptation and what the mechanism of changes in the transcriptome is remain unclear. In this study, three different N:Ca ratios were used to grow poplar seedlings, and physiological and transcriptomic methods were used to study the molecular mechanisms of poplar growth under nitrogen–calcium synergy and to determine the optimal N:Ca ratio for poplar seedling growth. The results of this study showed that maximum poplar seedling growth occurred in the treatment with an N:Ca ratio of 2, which resulted in significantly greater induction of growth than the two other treatments (p < 0.05). Under the lowest N:Ca ratio, poplar seedlings can ensure normal development by regulating photosynthesis, while under the highest N:Ca ratio, regulating nitrogen metabolism can achieve the same result. These results contribute to a better understanding of the molecular mechanisms by which poplar seedlings respond to different ratios of N:Ca. This study provides a valuable basis for exploring the synergistic effects of nitrogen and calcium on the growth of poplar shelterbelts. [ABSTRACT FROM AUTHOR]

Melatonin can improve plant adaptability to water deficit stress by regulating the biosynthesis of flavonoids and improving the reactive oxygen species-scavenging enzyme system. However, it remains unclear whether melatonin mitigates the effects and causes of water deficit stress in Cenchrus alopecuroides. We conducted a PEG-simulated water stress pot experiment to determine whether and how exogenous melatonin alleviates water deficit in C. alopecuroides. The experiment was divided into four treatments: (1) normal watering (Control), (2) 40% PEG-6000 treatment (D), (3) 100 μmol·L−1 melatonin treatment (MT), and (4) both melatonin and PEG-6000 treatment (DMT). The results showed that melatonin can alleviate water deficit in C. alopecuroides by effectively inhibiting plant chlorophyll degradation and MDA accumulation while increasing antioxidant enzyme activities and photosynthetic rates under water deficit stress. The transcriptome results indicated that melatonin regulates the expression of genes with the biosynthesis pathway of flavonoids (by increasing the expression of PAL, 4CL, HCT, and CHS), photosynthesis-antenna proteins (by increasing the expression of LHC), and sulfur metabolism (the expression of PAPSS and CysC is up-regulated in the assimilatory sulfate reduction pathway), while up-regulating the transcription factors (AP2/ERF-ERF-, C2H2-, WRKY-, Tify-, bHLH-, NAC-, and MYB-related). These findings revealed the possible causes by which melatonin mitigates water deficit stress in C. alopecuroides, which provided novel insights into the role of melatonin in water deficit stress.

The main objective of the current study is to underline the effects of salicylic acid or calcium chloride seed priming on plant growth, water content, chlorophyll content and photosynthetic activity of two barley species Hordeum marinum and Hordeum vulgare exposed to salinity (0, 100 and 200 mM NaCl). Results revealed that salinity decreased shoot and root growth, transpiration rate, chlorophyll concentration, stomata conductivity and water content in plants obtained from unprimed seeds. This reduction was dependent on the saline concentration used. However, Hordeum marinum species showed tolerance by maintaining tissue hydration, growth, photosynthetic assimilation and chlorophyll biosynthesis in stressed plants compared to controls. Moreover, priming seeds with salicylic acid or calcium chloride significantly improved all the above parameters under different salt treatments, suggesting that the effectiveness of this approach mainly depends on the priming agent applied and may vary with species and stress intensity applied. [ABSTRACT FROM AUTHOR]

Zanthoxylum armatum DC. is an economic tree species sensitive to waterlogging. Melatonin can improve the waterlogging tolerance of plants. In this study, we investigated the effects of different waterlogging times (including 0, 1, 2 and 3 d) and melatonin concentration (including 0, 400 and 800 μmol/L) on photosynthetic pigments, photosynthetic capabilities and chlorophyll fluorescence parameters of Z. armatum seedlings under waterlogging stress. Our results showed that waterlogging stress decreased the chlorophyll contents, photosynthetic rate (Pn), stomatal conductance (Gs), maximum efficiency of PSII photochemistry (Fv/Fm), quantum yield of PSII photochemistry (Y(II)), effective photochemical quantum yield of PSII (), as well as efficiency of electron transfer (ETR) with the increase of waterlogging time. On the contrary, the intercellular CO2 concentration (Ci), photochemical quenching (qP) and nonphotochemical quenching coefficient (NPQ) increased under waterlogging stress. However, melatonin could mitigate waterlogging-induced reductions in photosynthetic capacity. Melatonin improved photosynthesis by enhancing the chlorophyll and carotenoid content and photosynthesis rate. In addition, melatonin promotes stomatal function, electron transport in PSII and photosynthesis efficiency. Melatonin had a concentration-dependent effect on Z. armatum seedlings under waterlogging stress, and the optimum concentration is 400 μmol/L. It indicated that exogenous melatonin application could effectively ameliorate the repression of photosynthesis caused by waterlogging, and thus enhance the seedling tolerance to waterlogging stress. [ABSTRACT FROM AUTHOR]

In recent years, heat stress has become a serious threat to rice production in China. It is well documented that nitrogen forms can regulate the heat tolerance of plants. However, its effect on the rice plants has not been described before. In this study, a pot experiment was performed with two restorer lines of indica rice, heat-tolerant 996 (HT 996) and heat-sensitive 343 (HS 343), to investigate whether nitrogen forms could mitigate heat stress at flowering stage and their physiological mechanism. The experiment received five treatments: (1) NN0: natural temperature level (32 ℃) with urea-N; (2) HN0: high temperature level (38 ℃) with urea-N; (3) HN1: high temperature level with NH4+-N; (4) HN2: high temperature level with mixed N [NH4+: NO3− at 50: 50 (w:w)]; and (5) HN3: high temperature level with NO3−-N, respectively. The results showed that heat stress reduced seed setting, photosynthetic characteristics, leaf nitrogen content and antioxidant enzyme activities of rice. However, the application of mixed N significantly increased the 1000-grain weight and seed setting rate under heat stress, thus increasing yield. The increased yield was mainly caused by higher leaf N content, photosynthetic rate, transpiration rate and stomatal conductance, which led to a reduction in panicle and leaf temperatures. Meanwhile, the application of mixed N also improved the activities of antioxidant enzymes, and reduced the amount of reactive oxygen species, thereby mitigating the damage caused by exposure to high temperature. In conclusion, the application of mixed N can effectively alleviate the adverse consequences of high temperature, and could be further applied to provide strategies for the prevention and control of high temperature-prone areas during the rice flowering period. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine the effects of red and blue lights on the photomorphogenesis and photosynthetic traits of rice seedlings. The rice seedlings were cultured with red light (R), blue light (B), combined red and blue lights (R3B1/R1B1/R1B3), and white light (CK) as the control. The combined application of red and blue lights could promote the growth of rice seedlings to varying degrees; enhance photosynthesis by increasing the seedling leaf area, chlorophyll content, and chlorophyll fluorescence; improve root characteristics by increasing root number, root volume, and root activity; and thus increase the dry matter accumulation of rice seedlings. In addition, the combination of red and blue lights could regulate the expression of genes related to photosynthesis in rice leaves, affect the activity of the Rubisco enzyme, and then affect the photosynthesis of rice seedlings. These results indicate that red and blue lights have direct synergistic effects, which can regulate the growth of rice seedlings and promote the morphogenesis of rice seedlings. The combined application of red and blue lights can be used to supplement the light in rice-factory seedling raising. [ABSTRACT FROM AUTHOR]

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A field experiment was performed to investigate the physiological mechanism of the simultaneous stresses of waterlogging and shading on leaf photosynthetic and senescence during three growth stages of summer maize. The responses of leaf gas exchange parameters and antioxidant enzyme activities of the summer maize hybrids Denghai 605 (DH605) to waterlogging (W), shading (S), and their combination (W + S) for 6 days at the third leaf stage (V3), the sixth leaf stage (V6), and the tasseling stage (VT) were recorded. Shading, waterlogging, and their combination disturbed the activities of protective enzymes and increased the contents of H2O2 and O2−, accelerating leaf senescence and disordering photosynthetic characteristics. Under waterlogging, shading and their combination, leaf Pn, the photo-assimilates and grain yield was decreased. The greatest reduction for waterlogging and the combined stresses occurred at V3 and that for shading stress occurred at VT. The individual and combined stresses reduced the activities of protective enzymes and inhibited photosynthesis, reducing the accumulation of photosynthetic compounds and thereby yield. Waterlogging and the combined stresses at the V3 stage showed the greatest effect on leaf photosynthetic and senescence, followed by the V6 and VT stages. The greatest effect for shading stress occurred at VT, followed by the V6 and V3 stages, and the combined influence of shading and waterlogging was greater than that of either single stress.

Cu and Zn are common and potentially harmful heavy metals to plants, animals and humans. Herein, we investigated the effects of Cu and Zn stress on the photosynthesis and tolerance mechanism of alfalfa plants to ROS using fluorescence and biochemical methods. The results showed that Cu stress significantly reduced the chlorophyll content of the leaves, while Zn stress only reduced the Chl a content. The Fv/Fm decreased significantly under Cu stress but was not affected by Zn treatment. However, the PIABS of the leaves were sensitive to Cu and Zn stress. Both Cu and Zn stress resulted in the weakening of the ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QB. Moreover, Cu stress also dissociated the thylakoids of leaves, but Zn stress did not significantly damage it. In Cu and Zn stressed leaves, the reduction of RC/CSm significantly increased the ABS/RC and TRo/RC values. When the stress intensified, the value of DIo/RC increased indicated a plant self-protection mechanism that eliminates excess energy in the PSII reaction center and increases the energy for heat dissipation per unit reaction center. Cu stress significantly increased the O2- production rate, H2O2 content, and MDA accumulation in the leaves. However, Zn stress exhibited a minimal effect on the ROS production and oxidative damage in the alfalfa leaves but increased the O2- production rate at the concentration of 800 μmol·L−1. Cu stress increased the activities of SOD, POD, CAT, APX, and GPX in the leaves; however, leaves adapts to Zn stress by enhancing the activities of SOD and GPX. Thus under Cu stress, the degree of photoinhibition and oxidative damage in alfalfa leaves were significantly higher than under Zn stress.

Light‐harvesting system is an important way for capturing, transferring and utilizing light energy. It remains a key challenge to develop highly efficient artificial light‐harvesting systems. Herein, we report a supramolecular co‐assembly based on 5,10,15,20‐tetrakis (4‐hydroxyphenyl) porphyrin (THPP) and fluorescein derivatives as an artificial light‐harvesting systems. The assemblies use fluorescein derivatives as a donor and porphyrin (THPP) as an acceptor unit by covalent linkage and achieved fluorescence resonance energy transfer (FRET) owing to their strong spectral overlap and short distance. Firstly, three linkers of different chain lengths were synthesized through bromoalkane, and three fluorescein derivatives were obtained by connecting the linker and fluorescein through covalent bonds according to the principle of substitution reaction. Then, FRET systems between fluorescein derivatives and THPP were developed. As a result, a nanocapsule with an ultrathin shell designed for mimicking natural light‐harvesting systems was successfully constructed based on the covalent assembly of donor molecule called fluorescein and acceptor molecule called THPP. To our delight, the covalent FRET probes achieved enhanced energy transfer and a longer fluorescence lifetime. The covalent FRET probes also showed the obvious growth inhibition of Staphylococcus aureus cells in photodynamic antibacterial. Therefore, this study provides a new and efficient strategy to construct artificial light‐harvesting systems and they hold great promise for photophysical and photochemical applications. [ABSTRACT FROM AUTHOR]

This study was conducted to reveal the effects of bat guano on the growth, quality, content of photosynthetic pigments and nutrients of Begonia semperflorens L. under salt-free conditions, to determine the effects of salt stress on the related species, and to figure out whether there is an alleviating effect of bat guano on salt stress. For this purpose, 40 g (50 t ha-1) bat guano per pot was used at various sodium chloride (NaCl) applications, including 0, 20, 40, 50, and 60 mM. The experiment was conducted in plastic pots with a volume of 2 L containing the peat+perlite mixture (3:1) by using a completely randomized experimental design with five replications. Bat guano had effects on all studied traits at a 0.001 probability level without Chl a/b. This study revealed that the contents of Chl a, Chl b, and the concentrations of all nutrients in leaves of B. semperflorens highly decreased at 60 mM NaCl compared to control treatments. Bat guano treatment without NaCl increased over 25% root fresh and dry weights. Bat guano was used to improve the effects of salt stress on B. semperflorens. [ABSTRACT FROM AUTHOR]

Light, as an energy source, has been proven to strongly affect photosynthesis and, thus, can regulate the yield and quality of tea leaves (Camellia sinensis L.). However, few comprehensive studies have investigated the synergistic effects of light wavelengths on tea growth and development in green and albino varieties. Thus, the objective of this study was to investigate different ratios of red, blue and yellow light and their effects on tea plants' growth and quality. In this study, Zhongcha108 (green variety) and Zhongbai4 (albino variety) were exposed to lights of different wavelengths for a photoperiod of 5 months under the following seven treatments: white light simulated from the solar spectrum, which served as the control, and L1 (red 75%, blue 15% and yellow 10%), L2 (red 60%, blue 30% and yellow 10%), L3 (red 45%, far-red light 15%, blue 30% and yellow 10%), L4 (red 55%, blue 25% and yellow 20%), L5 (red 45%, blue 45% and yellow 10%) and L6 (red 30%, blue 60% and yellow 10%), respectively. We examined how different ratios of red light, blue light and yellow light affected tea growth by investigating the photosynthesis response curve, chlorophyll content, leaf structure, growth parameters and quality. Our results showed that far-red light interacted with red, blue and yellow light (L3 treatments) and significantly promoted leaf photosynthesis by 48.51% in the green variety, Zhongcha108, compared with the control treatments, and the length of the new shoots, number of new leaves, internode length, new leaf area, new shoots biomass and leaf thickness increased by 70.43%, 32.64%, 25.97%, 15.61%, 76.39% and 13.30%, respectively. Additionally, the polyphenol in the green variety, Zhongcha108, was significantly increased by 15.6% compared to that of the plants subjected to the control treatment. In addition, for the albino variety Zhongbai4, the highest ratio of red light (L1 treatment) remarkably enhanced leaf photosynthesis by 50.48% compared with the plants under the control treatment, resulting in the greatest new shoot length, number of new leaves, internode length, new leaf area, new shoot biomass, leaf thickness and polyphenol in the albino variety, Zhongbai4, compared to those of the control treatments, which increased by 50.48%, 26.11%, 69.29%, 31.61%, 42.86% and 10.09%, respectively. Our study provided these new light modes to serve as a new agricultural method for the production of green and albino varieties. [ABSTRACT FROM AUTHOR]

In China, cadmium (Cd) stress has a significant role in limiting the development and productivity of purple flowering stalks (Brassica campestris var. purpuraria). Exogenous selenium supplementation has been demonstrated in earlier research to mitigate the effects of Cd stress in a range of plant species; nevertheless, the physiological and molecular processes by which exogenous selenium increases vegetable shoots’ resistance to Cd stress remain unclear. Purple flowering stalks (Brassica campestris var. purpuraria) were chosen as the study subject to examine the effects of treatment with sodium selenite (Na2SeO3) on the physiology and transcriptome alterations of cadmium stress. Purple flowering stalk leaves treated with exogenous selenium had higher glutathione content, photosynthetic capacity, and antioxidant enzyme activities compared to the leaves treated with Cd stress alone. Conversely, the contents of proline, soluble proteins, soluble sugars, malondialdehyde, and intercellular CO2 concentration tended to decrease. Transcriptome analysis revealed that 2643 differentially expressed genes (DEGs) were implicated in the response of exogenous selenium treatment to Cd stress. The metabolic pathways associated with flavonoid production, carotenoid synthesis, glutathione metabolism, and glucosinolate biosynthesis were among those enriched in these differentially expressed genes. Furthermore, we discovered DEGs connected to the production route of glucosinolates. This work sheds fresh light on how purple flowering stalks’ tolerance to cadmium stress is improved by exogenous selenium.

Terrestrial LiDAR has emerged as a promising technology for accurate forest assessment. LiDAR can provide a 3D image composed of a cloud of points using a rotary laser scanner. The point cloud data (PCD) contain information on the (x, y, z) coordinates of every single scanned point and a raw intensity parameter. This study introduces an algorithm for the automatic and accurate separation of the photosynthetic features of a PCD. It is shown that the recorded raw intensity is not a suitable parameter for the separation of photosynthetic features. Instead, for the first time, the absorption intensity is developed for every point based on its raw intensity and distance from the scanner, using proper scaling functions. Then, the absorption intensity is utilized as the only criterion for the classification of the points between photosynthetic and non-photosynthetic features. The proposed method is applied to the scans from a Canadian Boreal Forest and successfully extracted the photosynthetic features with minimal average type I and type II error rates of 5.7% and 4.8%. The extracted photosynthetic PCD can be readily used for calculating important forest parameters such as the leaf area index (LAI) and the green biomass. In addition, it can be used for estimating forest carbon storage and monitoring temporal changes in vegetation structure and ecosystem health.

In order to explore the alleviating mechanism of phosphorus fertilizer postpone on the growth of wheat flag leaves under late spring coldness at connectivum stage, the low temperature simulation experiment of pot was carried out by using the artificial climate chamber with the wheat variety "Yannong 19" (YN19, strong resistance to reversed late spring coldness) and the wheat variety "Xinmai 26" (XM26 weak resistance to reversed late spring coldness) as experimental materials. In the experiment, two temperature treatments were set at connectivum stage of wheat: control(average daily temperature 15c, minimum night temperature 11c, CK) and low temperature(c4c, LT), and two phosphorus fertilizer application modes: conventional phosphorus fertilizer application which all of phosphorus fertilizer was applied as base fertilizer and phosphorus fertilizer postpone which half of phosphorus fertilizer was applied as jointing fertilizer. The low temperature treatment lasted for 4h·dc1. Photosynthetic and antioxidant physiological indices of flag leaves at flowering and grain filling stage and yield were analyzed. The results showed as follows: (1) compared with CK, the relative chlorophyll content (SPAD value), net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of flag leaves in LT treatment significantly decreased(P<0.05), while the intercellular CO2 concentration (Ci) significantly increased. (2) Compared with CK, LT treatment significantly decreased the activities of SOD and CAT, and significantly increased the content of malondialdehyde (MDA). (3) Under the experimental conditions, LT treatment significantly reduced the number of grains per spike, 1000 grains weight and single stem yield of the two varieties compared with CK treatment. (4) Compared with LTR1, the SPAD value of XM26 flag leaves at flowering stage and YN19 flag leaves at grain filling stage under LTR2 treatment were significantly increased by 7.3% and 10.1%, respectively. Pn of XM26 and YN19 flag leaves was significantly increased by 8.5% and 19.0% at flowering stage, 8.0% and 8.7% at grain filling stage, and there was no significant difference in Gs, Tr and Ci. (5) Compared with LTR1, SOD activity, CAT activity and MDA content of XM26 flag leaves at flowering and grain filling stages of LTR2 in were significantly increased by 9.0% and 5.7%, 12.4% and 30.9%, and 7.9% and 7.3%, respectively; SOD activity, CAT activity and MDA content of YN19 flag leaves at flowering and grain filling stages of LTR2 were significantly increased by 7.7% and 8.2%, 20.8% and 25.5%, and 6.8% and 7.0%, respectively. (6) Compared with R1, R2 significantly increased the grain number per spike of XM26 by 8.4% after LT treatment, but had no significant effect on the 1000 grains weight of the two cultivars. The yield recovery rates of XM26 and YN19 per stem could reach 8.9% and 9.9%. In conclusion, delayed phosphorus transfer can effectively enhance the antioxidant capacity of wheat flag leaf cells, reduce the degree of membrane lipid peroxidation, and improve the photosynthetic capacity of wheat flag leaf cells. Through the synergistic alleviation of antioxidant and photosynthetic capacity, the growth of flag leaves in the middle and late stage of wheat growth under reversed late spring coldness at connectivum stage, the number of grains per spike and 1000 grains weight of main stem were increased, the "source" was maintained and the "reservoir" was increased, and the effects of disaster free, stable and increased yield, disaster reduction and loss stopping were achieved. [ABSTRACT FROM AUTHOR]

Climate change issues have sparked intense debate around the world in recent years. Malaysia faces critical issues with global warming, which has changed the local climate, threatening critical ecosystems, including mangrove forests, and creating challenges in their habitat. This study was conducted to investigate the morphological and physiological attributes of the mangrove Rhizophora apiculata in response to air temperature for the selection of tree species that can adapt to climate change. The seedlings were grown in controlled growth chambers with temperatures, of 21,28, and 38 °C, under elevated CO2 at 650 ppm for three months. The plants were watered with three liters of 28-ppt saline water every 48 h. Thus, after two weeks, the mangrove plant samples recorded positive results for all parameters of high temperature. The differences in temperature resulted in significant differences and positive responses between elevated CO2 and decreased temperature, which led to the samples surviving for all parameters and the growth being very slow. However, when the temperature is raised, the result is negative, and almost all of the samples perish. These results suggested that the low level of photosynthetic capacity might be attributed to the decreased CO2 fixative reaction system and photosynthetic pigment contents. Additional physical and climatic factors have an impact on what determines the increase or decrease in R. apiculata growth. [ABSTRACT FROM AUTHOR]

Prolonged drought can negatively impact a variety of plant physiological processes. We conducted a drought experiment on one-year-old plants of Glycyrrhiza uralensis to characterize how gas exchange, chlorophyll fluorescence, the activities of antioxidant enzymes, and growth responded to droughts of varying magnitudes. Plants grown under control (no drought stress) and three droughted conditions, differing in their duration (7, 14 and 21 days). Net photosynthetic rate (Pn), transpiration rate (E), and stomatal conductance (gs) were significantly lower with increasing water stress. The moderate (14 days) and severe (21 days) water stress treatments resulted in lower Pn, as well as stomatal limitation of photosynthesis during the morning but nonstomatal limitation during the afternoon. Meanwhile, the increase in F0 and decrease in Fm, ΦPSII, and Fv/Fm further suggested that photosynthetic capacity of G. uralensis leaves was reduced and PSII partially inactivated during the day under drought. These patterns indicated that drought damaged PSII of G. uralensis leaves. However, part of the damage to PSII might be alleviated under mild or moderate drought, but it was not reparable under severe drought. Water stress decreased the Pn-PAR curves of G. uralensis and led to higher LCP and RD and lower Pmax and LSP. Together, these results suggest that drought stress weakened the light adaptability of leaves and reduced the efficiency of light transformation. In addition, the activities of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) were elevated in G. uralensis under moderate (14 days) and severe (21 days) water stress during first 14 days but were significantly reduced after that time. These results suggest that protective enzymes were activated early to resist the damage caused by drought stress but that prolonged stress caused accumulation of reactive oxygen species that exceeded the capacity of the antioxidant system, resulting in cellular damage. Water stress also reduced plant growth (lower plant height, basal diameter and crown area) and yield (smaller roots, stems, leaves, and total biomass). Moreover, water stress led to yellowing, wilting, and senescence of leaves and suppressed growth of main roots. We found that the drought treatment lasting 21 days is the moisture threshold of G. uralensis, and that longer droughts in the Hexi Corridor can cause G. uralensis to wither and die. [ABSTRACT FROM AUTHOR]

Cu and Zn are common and potentially harmful heavy metals to plants, animals and humans. Herein, we investigated the effects of Cu and Zn stress on the photosynthesis and tolerance mechanism of alfalfa plants to ROS using fluorescence and biochemical methods. The results showed that Cu stress significantly reduced the chlorophyll content of the leaves, while Zn stress only reduced the Chl a content. The Fv/Fm decreased significantly under Cu stress but was not affected by Zn treatment. However, the PIABS of the leaves were sensitive to Cu and Zn stress. Both Cu and Zn stress resulted in the weakening of the ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QB. Moreover, Cu stress also dissociated the thylakoids of leaves, but Zn stress did not significantly damage it. In Cu and Zn stressed leaves, the reduction of RC/CSm significantly increased the ABS/RC and TRo/RC values. When the stress intensified, the value of DIo/RC increased indicated a plant self-protection mechanism that eliminates excess energy in the PSII reaction center and increases the energy for heat dissipation per unit reaction center. Cu stress significantly increased the O2- production rate, H2O2 content, and MDA accumulation in the leaves. However, Zn stress exhibited a minimal effect on the ROS production and oxidative damage in the alfalfa leaves but increased the O2- production rate at the concentration of 800 μmol·L−1. Cu stress increased the activities of SOD, POD, CAT, APX, and GPX in the leaves; however, leaves adapts to Zn stress by enhancing the activities of SOD and GPX. Thus under Cu stress, the degree of photoinhibition and oxidative damage in alfalfa leaves were significantly higher than under Zn stress. [ABSTRACT FROM AUTHOR]

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Tannery industries discharge a high concentration of chromium (Cr) along with other heavy metals, which are hazardous for all life forms. With increasing shortage of freshwater, tannery effluent is frequently used for crop an irrigation, causing damage to plants' health. In order to address this challenge, amino acid chelate fertilizer was used to investigate the impact on wheat crops against tannery waste water. Tannery wastewater (TW) was used at different levels such as 0%, 25%, 50%, and 100% with an amendment of foliar Zn-lysine (Zn-lys) at30 mg/L. This research highlighted the positive correlation of Zn-lysine on the morpho-physiological, biochemical, and gas exchange traits under different levels of tannery wastewater. The findings of this study showed that the application of Cr-rich tannery wastewater at different treatment levels resulted in a significant reduction in plant height (23%, 31%, and 36%), the number of tillers (21%, 30%, and 43%), spike (19%, 36%, and 55%) and dry weight (DW) of grains (10%, 25%, and 49%) roots DW (17%, 41%, 56%), and shoots DW (22%, 32%, and 47%) as compared to control. Foliar-applied Zn-lys positively enhanced photosynthetic attributes, antioxidant enzymes activities and gas exchange traits by reducing the oxidative stress alone and under Cr stress. The concentration of Cr in roots (21%, 37%, 38%) and shoots (11%, 36%, 37%) was reduced by the foliar application of Zn-lys at different treatment levels. These findings conclude that Zn-lys served as a protector for the growth and development of wheat and has an incredible potential to inhibit the phytotoxicity induced by excess Cr. [ABSTRACT FROM AUTHOR]

The concept of agrivoltaics (APV) has made progress in recent years but has not yet been widely promoted and applied on a larger scale. The main hindrance lies in the fact that the effects on crop cultivation have not been optimal. This study establishes two sets of single-axis dynamic tracking photovoltaic (PV) systems utilizing bifacial modules: Solar tracking (ST) employing the maximum power generation strategy, and Reverse tracking (RT) employing the minimum shadow area tracking strategy for ground-mounted tracking. In Xiongan (N39.02°, E116.11°), ST increases power generation by 3.9% compared to fixed-axis PV systems (Tilt = 25°), while RT decreases power generation by 34.7%. The discrepancy in power generation between ST and RT is most noticeable on clear sky and partly cloudy days, with minimal difference on cloudy days. We investigate the impact of these systems on crop growth by analyzing changes in canopy area during the lettuce growing period and compare the net photosynthetic rates (P n) of spring wheat (C 3 crop) and millet (C 4 crop) using canopy photosynthesis and transpiration measurement systems (CAPTS). The results indicate that lettuce shows a larger leaf area under ST throughout the growing period, millet exhibits a higher net photosynthetic rate under RT, while there is marginal difference in the P n of spring wheat under both systems. This study integrates the above research configuration with Chinese Solar Greenhouses (CSGs) located in Yufa, Beijing. During the production season, the dynamic PV systems switch to the shadow-free mode to ensure the photosynthesis of crops within the CSGs. Conversely, during the idle season of the CSGs, the system shifts to ST mode to ensure PV power generation. By integrating power generation and planting data, the Land Equivalent Ratio (LER) can reach 1.46, with the Return on Investment (ROI) of 20% based on construction costs. Through experiments and practical case studies, it is evident that dynamic PV systems can be effectively integrated with CSGs, providing sufficient land and space for both PV power generation and crop cultivation. • Analyzing the spatial and temporal distribution patterns of light fields under agrivoltaics (APV). • Applying phenotypic and canopy photosynthesis techniques to the study of plants under APV. • Integrating dynamic photovoltaic strategies with crop stubble. • A large-scale case comprising 60 photovoltaic greenhouses was completed. [ABSTRACT FROM AUTHOR]