Affect Plant Photosynthesis Research Articles

Characterization, Phylogenetic Analyses, and Pathogenicity of Eutiarosporella dactylidis on Sorghum in China.

Sorghum, the fifth-largest cereal crop globally and a C4 crop, mainly grows in arid and semi-arid areas. In 2021-2023, a new foliar disease of sorghum occurred in China. The diseased leaves showed water-soaked symptoms in the leaf tip and margins, resulting in half- and full-leaf desiccation and necrosis, thus affecting plant photosynthesis. A total of 24 Eutiarosporella strains were isolated from symptomatic leaves. Based on morphological characteristics and multi-locus phylogenetic analysis involving ITS, LSU, and EF1-α sequences, and the pathogenicity test, the pathogen of sorghum causing leaf blight in China was identified as Eutiarosporella dactylidis. The virulence of all E. dactylidis strains was evaluated using the spray-mycelium method. Different strains showed significantly different pathogenicities toward a susceptible cultivar, Longza 10, with disease indexes ranging from 23.76 to 60.37. This study first reported leaf blight of sorghum caused by E. dactylidis and named it "Eutiarosporella leaf blight", which provides a theoretical basis for farmers in disease management.

Assessing the Efficacy of Cyanobacterial Strains as Oryza sativa Growth Biostimulants in Saline Environments.

Soil salinity, which affects plant photosynthesis mechanisms, significantly limits plant productivity. Soil microorganisms, including cyanobacteria, can synthesize various exometabolites that contribute to plant growth and development in several ways. These microorganisms can increase plant tolerance to salt stress by secreting various phytoprotectants; therefore, it is highly relevant to study soil microorganisms adapted to high salinity and investigate their potential to increase plant resistance to salt stress. This study evaluated the antioxidant activity of four cyanobacterial strains: Spirulina platensis Calu-532, Nostoc sp. J-14, Trichormus variabilis K-31, and Oscillatoria brevis SH-12. Among these, Nostoc sp. J-14 presented the highest antioxidant activity. Their growth-stimulating effects under saline conditions were also assessed under laboratory conditions. These results indicate that Nostoc sp. J-14 and T. variabilis K-31 show significant promise in mitigating the harmful effects of salinity on plant size and weight. Both strains notably enhanced the growth of Oryza sativa plants under saline conditions, suggesting their potential as biostimulants to improve crop productivity in saline environments. This research underscores the importance of understanding the mechanisms by which cyanobacteria increase plant tolerance to salt stress, paving the way for sustainable agricultural practices in saline areas.

Photosynthetic performance of glumes of oat spikelets is more stable for grain-filling stage under drought stress

Drought stress affects plant photosynthesis, leading to a reduction in the quality and yield of crop production. Non-foliar organs play a complementary role in photosynthesis during plant growth and development and are important sources of energy. However, there are limited studies on the performance of non-foliar organs under drought stress. The photosynthetic-responsive differences of oat spikelet organs (glumes, lemmas and paleas) and flag leaves to drought stress during the grain-filling stage were examined. Under drought stress, photosynthetic performance of glume is more stable. Intercellular CO2 concentration (Ci), chlorophyll b, maximum photochemical efficiency of photosystem II. (Fv/Fm), and electron transport rate (ETR) were significantly higher in the glume compared to the flag leaf. The transcriptome data revealed that stable expression of the RCCR gene under drought stress was the main reason for maintaining higher chlorophyll content in the glume. Additionally, no differential expression genes (DEGs) related to Photosystem Ⅰ (PSI) reaction centers were found, and drought stress primarily affects the Photosystem II (PSII) reaction center. In spikelets, the CP43 and CP47 subunits of PSII and the AtpB subunit of ATP synthase were increased on the thylakoid membrane, contributing to photosynthetic stabilisation of spikelets as a means of supplementing the limited photosynthesis of the leaves under drought stress. The results enhanced understanding of the photosynthetic performance of oat spikelet during the grain-filling stage, and also provided an important basis on improving the photosynthetic capacity of non-foliar organs for the selection and breeding new oat varieties with high yield and better drought resistance.

Stomatal evolution and plant adaptation to future climate.

Global climate change is affecting plant photosynthesis and transpiration processes, as well as increasing weather extremes impacting socio-political and environmental events and decisions for decades to come. One major research challenge in plant biology and ecology is the interaction of photosynthesis with the environment. Stomata control plant gas exchange and their evolution was a crucial innovation that facilitated the earliest land plants to colonize terrestrial environments. Stomata couple homoiohydry, together with cuticles, intercellular gas space, with the endohydric water-conducting system, enabling plants to adapt and diversify across the planet. Plants control stomatal movement in response to environmental change through regulating guard cell turgor mediated by membrane transporters and signaling transduction. However, the origin, evolution, and active control of stomata remain controversial topics. We first review stomatal evolution and diversity, providing fossil and phylogenetic evidence of their origins. We summarize functional evolution of guard cell membrane transporters in the context of climate changes and environmental stresses. Our analyses show that the core signaling elements of stomatal movement are more ancient than stomata, while genes involved in stomatal development co-evolved de novo with the earliest stomata. These results suggest that novel stomatal development-specific genes were acquired during plant evolution, whereas genes regulating stomatal movement, especially cell signaling pathways, were inherited ancestrally and co-opted by dynamic functional differentiation. These two processes reflect the different adaptation strategies during land plant evolution.

Exploration of the Effects of Cadmium Stress on Photosynthesis in Oenanthe javanica (Blume) DC.

Cadmium ion (Cd2+) stress is a major abiotic stressor affecting plant photosynthesis. However, the impact of sustained high-concentration Cd stress on the photosynthetic electron transport chain of aquatic plants is currently unclear. Here, prompt fluorescence (PF), delayed fluorescence (DF), and P700 signals were simultaneously measured to investigate the effect of Cd stress on photosynthesis in water dropwort [Oenanthe javanica (Blume) DC.]. We aimed to elucidate how Cd stress continuously affects the electron transport chain in this species. The PF analysis showed that with prolonged Cd stress, the FJ, FI and FP steadily decreased, accompanied by a positive shift in the K-band and L-band. Moreover, JIP-test parameters, including TRO/ABS, ABS/CSO, TRO/CSO and PIABS, were significantly reduced. The P700 signals showed that exposure to Cd stress hindered both the fast decrease and slow increase phases of the MR transient, ultimately resulting in a gradual reduction in both VPSI and VPSII-PSI. The DF analysis showed a gradual decrease in the I1 and I2 values as the duration of stress from Cd increased. The above results suggested that Cd stress affected the photosynthetic electron transport in water dropwort by influencing the amount of active PSII and PSI, primarily affecting PSII RCs in the early to mid-stages and PSI reductive activity in the later stage.

MiR397b-LAC2 module regulates cadmium stress response by coordinating root lignification and copper homeostasis in Arabidopsis thaliana

Non-essential heavy metal cadmium (Cd) is toxic to plants and animals. Cadmium affects plant photosynthesis, respiration, and causes water imbalance and may lead to plant death. Cadmium induces toxicity by interfering with the essential metal copper (Cu) homeostasis, which affects plant nutrition. Though root lignin biosynthesis is positively regulated by Cd stress, the underlying mechanisms promoting lignin accumulation and controlling Cd-induced Cu limitation responses are unclear. Here, we elucidated the role of Cu-responsive microRNA (miR397b) in Arabidopsis thaliana plants for Cd stress by targeting the LACCASE2 (LAC2) gene. This study demonstrated the fundamental mechanism of miR397b-mediated Cd stress response by enhancing the lignin content in root tissues. We developed miR397b over-expressing plants, which showed considerable Cd stress tolerance. Plants with knockdown function of LAC2 also showed significant tolerance to Cd stress. miR397b overexpressing and lac2 mutant plants showed root reduction, higher biomass and chlorophyll content, and significantly lower Reactive Oxygen Species (ROS). This study demonstrated the miR397b-mediated Cd stress response in Arabidopsis by enhancing the lignin content in root tissues. We conclude that modulation in miR397b can be potentially used for improving plants for Cd tolerance and Cu homeostasis.

Divergences in leaf CO2 diffusion conductance and water use efficiency of soybean coping with water stress and its interaction with N addition

Drought and nitrogen (N) additions have been shown to affect plant photosynthesis, but the effect of their interaction on CO2 diffusion conductance (i.e., stomatal conductance, gsc, mesophyll conductance, gm) and water use efficiency (WUE) at the leaf level (i.e., instantaneous water use efficiency, WUEins; intrinsic water use efficiency, WUEint) has rarely been reported. Herein, we examined the interactive effects of drought and N addition on gsc and gm and WUE (i.e., WUEins and WUEint) in soybean (Glycine max (Linn.) Merr.) and analysed the interaction mechanisms mitigating water stress based on leaf anatomy and molecular activity. Drought decreased gsc,gm and WUEins, but N addition had a positive interactive effect with water stress on leaf physiological traits. The variables gsc, gm and WUEins were significantly increased by the additions of 7.5 and 15.0 g urea m−2 under moderate water stress (MW) conditions (P < 0.05), but they decreased under the interaction effect of SW and N addition. The decreased Tcw and increased Sm and Sc under the water stress × N addition interaction positively affected gm, and the increased SS dominated the gsc increase. In addition, these positive effects were further enhanced with increased AQP, CA and Rubisco activities and a decrease in the ABA content. Accordingly, moderate soil N additions of 7.5 and 15.0 g urea m−2 greatly mitigated the negative effects of droughts, especially the MW effects, by enhancing CO2 diffusion conductance and WUE.

The Response of Plants to Soil Pb Stress

The problem of soil heavy metal pollution is becoming increasingly serious, and Pb is one of the main causes of soil heavy metal pollution due to its toxicity. Phytoremediation technology can reduce the content of heavy metal pollutants and improve soil nutrient conditions, and thus, it is more widely used. Pb in the soil affects the physiological and biochemical processes of plants, which in turn have a toxic effect on plants, causing severe wilting and death. Similarly, Pb also affects plant photosynthesis to varying degrees. This paper details the progress of research on the effects of soil Pb contamination on plants, with the aim of finding directions for further study.

Enhancing alfalfa photosynthetic performance through arbuscular mycorrhizal fungi inoculation across varied phosphorus application levels

This study evaluated the effects of arbuscular mycorrhizal fungi inoculation on the growth and photosynthetic performance of alfalfa under different phosphorus application levels. This experiment adopts two-factors completely random design, and sets four levels of fungi application: single inoculation with Funneliformis mosseae (Fm, T1), single inoculation with Glomus etunicatum (Ge, T2) and mixed inoculation with Funneliformis mosseae × Glomus etunicatum (Fm×Ge, T3) and treatment uninfected fungus (CK, T0). Four phosphorus application levels were set under the fungi application level: P2O5 0 (P0), 50 (P1), 100 (P2) and 150 (P3) mg·kg-1. There were 16 treatments for fungus phosphorus interaction. The strain was placed 5 cm below the surface of the flowerpot soil, and the phosphate fertilizer was dissolved in water and applied at one time. The results showed that the intercellular CO2 concentration (Ci) of alfalfa decreased at first and then increased with the increase of phosphorus application, except for light use efficiency (LUE) and leaf instantaneous water use efficiency (WUE), other indicators showed the opposite trend. The effect of mixed inoculation (T3) was significantly better than that of non-inoculation (T0) (p &amp;lt; 0.05). Pearson correlation analysis showed that Ci was significantly negatively correlated with alfalfa leaf transpiration rate (Tr) and WUE (p &amp;lt; 0.05), and was extremely significantly negatively correlated with other indicators (p &amp;lt; 0.01). The other indexes were positively correlated (p &amp;lt; 0.05). This may be mainly because the factors affecting plant photosynthesis are non-stomatal factors. Through the comprehensive analysis of membership function, the indexes of alfalfa under different treatments were comprehensively ranked, and the top three were: T3P2&amp;gt;T3P1&amp;gt;T1P2. Therefore, when the phosphorus treatment was 100 mg·kg-1, the mixed inoculation of Funneliformis mosseae and Glomus etunicatum had the best effect, which was conducive to improving the photosynthetic efficiency of alfalfa, increasing the dry matter yield, and improving the economic benefits of local alfalfa in Xinjiang. In future studies, the anatomical structure and photosynthetic performance of alfalfa leaves and stems should be combined to clarify the synergistic mechanism of the anatomical structure and photosynthetic performance of alfalfa.

Combining Biometric, Biochemistry, and Photosynthetic Measurements to Analyze the Performance of Two Black Pepper Cultivars Under Water Deficit

ABSTRACT Low water availability affects plant photosynthesis, growth, and yield. In this study, physiological and biometric traits were evaluated in black pepper cultivars (Kottanadan and Bragantina) growing under water deficit conditions, according to a randomized block design, with two factors [two pepper cultivars and six water deficit levels]. Nine replicates were used for each treatment. The plant survival percentage was 90% and 10% in Kottanadan (after 12 WDD) and Bragantina (after 10 WDD), respectively. Relative water content (RWC), photosynthetic pigments, and JIP-test parameters were reduced in Bragantina pepper cultivar with water deprivation, except the basal quantum yield of the process non-photochemical in PSII (Fo/Fm), which increased with water deficit. Shoot and root dry matter accumulation, leaf number, and root volume were reduced at 10 and 12 WDD in Bragantina and Kottanadan pepper cultivars, respectively. The results obtained in this study showed that the two pepper cultivars differed strongly in their responses to the water deficit. The Kottanadan pepper cultivar showed an advantage over the Bragantina considering their high photochemical performance maintained until 12 WDD, showing better stability and efficiency in utilizing excitation energy under low water availability.

An effector of Erysiphe necator translocates to chloroplasts and plasma membrane to suppress host immunity in grapevine.

The powdery mildew (Erysiphe necator) is a prevalent pathogen hampering grapevine growth in the vineyard. An arsenal of candidate secreted effector proteins (CSEPs) was encoded in the E. necator genome, but it is largely unclear what role CSEPs plays during the E. necator infection. In the present study, we identified a secreted effector CSEP080 of E. necator, which was located in plant chloroplasts and plasma membrane. Transient expressing CSEP080 promotes plant photosynthesis and inhibits INF1-induced cell death in tobacco leaves. We found that CSEP080 was a necessary effector for the E. necator pathogenicity, which interacted with grapevine chloroplast protein VviB6f (cytochrome b6-f complex iron-sulfur subunit), affecting plant photosynthesis. Transient silencing VviB6f increased the plant hydrogen peroxide production, and the plant resistance to powdery mildew. In addition, CSEP080 manipulated the VviPE (pectinesterase) to promote pectin degradation. Our results demonstrated the molecular mechanisms that an effector of E. necator translocates to host chloroplasts and plasma membrane, which suppresses with the grapevine immunity system by targeting the chloroplast protein VviB6f to suppress hydrogen peroxide accumulation and manipulating VviPE to promote pectin degradation.

Genetic and transcriptome analysis of a cotton leaf variegation mutant

In eukaryotic photosynthetic organisms, chloroplast is not only a site for photosynthesis, but it also have a vital role in signal transduction mechanisms. Plants exhibit various colors in nature with various mutants induced by EMS, whose traits are regulated by developmental and environmental factors, making them ideal for studying the regulation of chloroplast development. In this study, the cotton leaf variegated mutant (VAR) induced by EMS was used for this experiment. Genetic analysis revealed that VAR phenotype was a dominant mutation and by performing freehand section inspection, it was noticed that the vascular bundles of VAR were smaller. Chloroplast ultrastructure showed that the stacking of grana thylakoid was thinner and the starch granules were increased significantly in VAR comparedto wild type (WT). Transcriptome analysis found that the KEGG was enriched in photosynthesis pathway, and GO was abundant in zinc ion transmembrane transport, electron transporter and cation binding terms. In addition, GhFTSH5 expression in VAR was significantly higher than WT and the promoter sequence of GhFTSH5 had differences. The results showed that the VAR plant had altered GhFTSH5 expression and disrupted chloroplast structure, which in turn affects plant photosynthesis. More importantly, this study lays a foundation for further analyzing molecular mechanism of cotton variegated phenotypes.

The ability of three climbing plant species to capture particulate matter and their physiological responses at different environmental sampling sites

The adsorption of particulate matter (PM) by the leaves of urban plants can effectively reduce the particulate matter concentration in the atmosphere. The use of climbing plants to abate particulate matter is an important means of urban greening in China, which is rich in climbing plant species. In this study, three evergreen climbing plants were selected to assess their ability to adsorb particulate matter and determine their physiological responses to particulate pollution. PM deposition was determined gravimetrically. There were four key results. 1) The adsorption capacity of the three evergreen climbers followed the order of Hedera nepalensis var &amp;gt; Ficus pumila Linn &amp;gt; Euonymus fortunei, and was significantly higher in an overpass environment than in a campus environment for all three species. 2) The seasonal characteristics of particulate adsorption by the three types of climbers in both the overpass and campus environments followed the order of winter &amp;gt; autumn &amp;gt; spring &amp;gt; summer. 3) The net photosynthetic rate of the three climbing plants was significantly affected by particulate matter in a size dependent manner, with fine particulate matter on the plant leaf surface and coarse particulate matter in the leaf waxy layer being important factors affecting plant photosynthesis. 4) Particulate pollution led to changes in the activities of plant protective enzymes in plants, with increases in the superoxide dismutase (SOD) and peroxidase (POD) activity, and the malondialdehyde (MDA) and soluble protein contents. There were different trends in the soluble sugar content among the different plant species. In conclusion, F. pumila had a strong resistance to particulate pollutants, while H. nepalensis was considered suitable for planting in polluted areas where it could improve ambient air quality by adsorbing large amounts of particulate matter.

​​The Biofertilizer Production for Salinity Stress in Plants: A Review

Biotic and abiotic factors are environmental factors that play a vital role in plant growth and productivity. Abiotic stress like drought, salinity environmental pollution has done major damage to the productivity of crops. According to the study by the United Nations Environment Program approximately 20% of agricultural land and 50% of cropland in the world is under the salt-stress. Salinization of soil converts agricultural land to barren land. There is an estimate that every year 1-2% decrease in agricultural land. Salinity affects plant photosynthesis, protein synthesis, lipid metabolism. The growing population in the whole world demands a simple low-cost method to reduce the effect of salinity on lands. The tremendous use of chemical fertilizers has created environmental problems such as deterioration of soil quality and surface as well as groundwater quality. Reduced biodiversity and suppressed ecosystem function are side effects of using chemical fertilizers. Thus, to overcome this ecological crisis, microorganisms that allow more increased nutrient availability in soil, can provide sustainable solutions for current and future agricultural scenarios. Microorganisms that are native in saline soil are having inherent properties such as tolerance to saline conditions and beneficial interaction with the plants, by synthesis of compatible solutes, production of plant growth-promoting hormones. Such microorganisms help in the growth of plants by mechanisms direct or indirect. Some mechanisms are phosphate solubilization and ammonia production, these chemicals act as macronutrients. The bacterial chitinase, siderophores, HCN, production in the rhizosphere suppress hazardous effects resulting from biotic stress thus helping indirectly on plant growth. The isolation of novel microorganisms can be a useful tool to deal with the salinity stress and thus these organisms should be examined further to have a greater understanding of the stress management mechanism by PGPR and also their role in biodiversity. This competent microorganism can be converted to biofertilizers and the local farmers can be helped by educating about this efficient environment safe biofertilizers.

Substrate pH Influences the Nutrient Absorption and Rhizosphere Microbiome of Huanglongbing-Affected Grapefruit Plants

The substrate pH directly affects nutrient availability in the rhizosphere and nutrient uptake by plants. Macronutrients such as nitrogen, potassium, calcium, magnesium, and sulfur are highly available at pH 6.0–6.5, while micronutrients become less available at higher, alkaline pH (pH > 7.0). Recent research has indicated that low pHs can enhance nutrient uptake and improve sweet orange (Citrus sinensis) tree health. We designed a study to understand the influence of a wide range of substrate pH values on plant size and biomass, nutrient availability, leaf gas exchange, and rhizosphere microbiome of grapefruit (Citrus paradisi) affected by Huanglongbing (HLB). Two-year-old “Ray Ruby” grapefruit plants grafted on sour orange (Citrus aurantium) rootstock were cultivated indoors in 10-cm wide × 40-cm tall pots with peat:perlite commercial substrate (80:20 v/v). We tested two disease statuses [HLB-free or healthy (negative, HLB–) and HLB-affected (positive, HLB+)] and six substrate pH values (4, 5, 6, 7, 8, 9) in a 2 × 6 factorial arranged on a complete randomized design with four replications. The canopy volume of HLB+ plants was 20% lower than healthy plants, with pHs 7 and 9 resulting in 44% less canopy volume. The root and shoot ratio of dry weight was 25.8% lower in HLB+ than in healthy plants. Poor root growth and a decrease in fibrous roots were found, especially in pH 5 and 6 treatments in HLB+ plants (p < 0.0001). The disease status and the substrate pHs influenced the leaf nutrient concentration (p < 0.05). High substrate pH affects nutrient availability for root uptake, influencing the nutrient balance throughout the plant system. pH values did not affect plant photosynthesis, indicating that pH does not recover HLB+ plants to the photosynthetic levels of healthy plants—even though high pH positively influenced internal CO2. There were collectively over 200 rhizobacterial identified by the 16S rRNA gene sequencing in individual phylogenetic trees. Most rhizobacteria reads were identified in pH 9. Our results indicated no effect of substrate pHs on the plant disease status induced by enhanced nutrient uptake.

Differential responses of leaf photosynthesis to insect and pathogen outbreaks: A global synthesis

Outbreak of insects or pathogens (referred to as biotic disturbance), which is projected to continually increase in a warmer climate, may profoundly affect plant photosynthesis and production. However, the response of plant photosynthesis to biotic disturbance remains unclear, especially differences in response between insects and pathogens, which hinders the prediction of plant productivity in future climate. In this study, a meta-analysis approach was used to examine effects of insects and pathogens on photosynthetic rate per unit leaf area (Pn) and the associated characteristics from 115 studies. Our results showed that biotic disturbance significantly decreased Pn by 34.8% but increased Rd by 26.2%. Most of parameters associated with Pn were significantly reduced by biotic disturbance, including gs, Tr, photosynthetic pigments (e.g., a+b, a, and b), and chlorophyll fluorescence properties (Fv/Fm, qp). The disturbance type (insects vs pathogens) was the most important factor affecting the response of Pn, with a greater decrease in Pn by pathogens (−37.5%) than insects (−28.0%). The response ratio of Pn was positively correlated with that of gs and Tr for both insects and pathogens, while negatively with Ci and positively with Chl a+b, ΦPSII, and qp for only pathogens. In addition, the higher sensitivity of Pn to biotic disturbance in crop than non-crop plants poses a great challenge to agricultural system in the future. The weighted response ratio of Pn and relationships of Pn with other associated paramerters under insect and pathogen disturbance will facilitate vegetation models to integrate the effects of biotic disturbance on primary production, improving predicition of the ecosystem carbon cyling in combining with leaf area measurement.

Could ammonium nutrition increase plant C-sink strength under elevated CO2 conditions?

Atmospheric carbon dioxide (CO2) is increasing, and this affects plant photosynthesis and biomass production. Under elevated CO2 conditions (eCO2), plants need to cope with an unbalanced carbon-to-nitrogen ratio (C/N) due to a limited C sink strength and/or the reported constrains in leaf N. Here, we present a physiological and metabolic analysis of ammonium (NH4+)-tolerant pea plants (Pisum sativum L., cv. snap pea) grown hydroponically with moderate or high NH4+ concentrations (2.5 or 10 mM), and under two atmospheric CO2 concentrations (400 and 800 ppm). We found that the photosynthetic efficiency of the NH4+ tolerant pea plants remain intact under eCO2 thanks to the capacity of the plants to maintain the foliar N status (N content and total soluble proteins), and the higher C-skeleton requirements for NH4+ assimilation. The capacity of pea plants grown at 800 ppm to promote the C allocation into mobile pools of sugar (mainly sucrose and glucose) instead of starch contributed to balancing plant C/N. Our results also support previous observations: plants exposed to eCO2 and NH4+ nutrition can increase of stomatal conductance. Considering the C and N source-sink balance of our plants, we call for exploring a novel trait, combining NH4+ tolerant plants with a proper NH4+ nutrition management, as a way for a better exploitation of eCO2 in C3 crops.

大气气溶胶对北京杨树人工林生态系统生产力的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 大气气溶胶对北京杨树人工林生态系统生产力的影响 DOI: 10.5846/stxb202005281383 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31872711） Effects of atmospheric aerosols on the ecosystem productivity of a poplar plantation in Beijing Author: Affiliation: Fund Project: Impact Mechanisms of Atmospheric Aerosols on Forest Ecosystem Carbon and Water Coupling 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:大气气溶胶可以影响到达地面的太阳辐射，进而影响植物光合作用和生态系统生产力，乃至区域上的碳收支。为探究北京地区气溶胶对杨树人工林生态系统生产力的影响，利用2006-2009年北京大气气溶胶数据结合北京大兴杨树人工林涡度相关系统监测的辐射、碳通量等数据，分析了气溶胶对散射辐射、光能利用效率（LUE）、生态系统初级生产力（GPP）的影响，并利用通径分析方法探究了气溶胶和生态环境因子对GPP的直接和间接影响。结果表明，北京市气溶胶光学厚度（AOD）具有明显的季节变化特征：春、夏两季大于秋、冬季，夏季气溶胶光化学厚度最大。大气气溶胶显著影响了地表辐射组分以及温度、湿度环境因子，随着AOD从0增大到3，总辐射减小了43.63%，散射辐射增加132.26%，散射辐射比例增大了2.55倍，而相对湿度增大48.52%，日温差增大3℃左右。当生态系统受水分胁迫时，气溶胶对生态系统生产力无显著影响，当生态系统处于非水分胁迫时，杨树人工林生态系统光能利用效率和生产力随着气溶胶浓度增大先增大后减小，当AOD为1.0-1.6时，GPP维持在较高的水平，当AOD>2.5时，GPP显著减小且小于背景气溶胶（AOD<0.4）的GPP。通径分析表明，水分胁迫条件下，气溶胶对杨树人工林生态系统生产力的间接影响很小；非水分条件下，散射辐射对生态系统生产力影响最大，气溶胶可以通过增大散射光施肥效应来增大生态系统生产力。不同的水分条件下气溶胶对杨树人工林生态系统的影响不同，非水分胁迫条件下适宜的气溶胶增大杨树人工林生态系统的生产力，严重的气溶胶污染（AOD>1.5）则导致杨树生态系统生产力下降。 Abstract:Atmospheric aerosols can affect the solar radiation reaching the ground, which in turn affects plant photosynthesis and ecosystem productivity, and even regional carbon balance. With the further development of global change, atmospheric aerosols pollution and drought stress coexist in some regions, and the high frequency and long duration of drought stress may lead to the conversion of ecosystems from carbon sinks to carbon sources. However, little is known about whether atmospheric aerosols can increase ecosystem productivity when the ecosystem are under water stress. Therefore, in this study we investigated the effects of atmospheric aerosols on diffuse radiation, light utilization efficiency (LUE) and the gross primary productivity (GPP) of poplar plantation under different water conditions in Beijing. The direct and indirect effects of atmospheric aerosols and ecological factors on GPP were explored by the path analysis method, which used the atmospheric aerosols data from 2006 to 2009 and combined with the radiation and carbon flux data monitored by Eddy covariance system in Daxing poplar in Beijing. The results showed that Beijing's atmospheric optical depth (AOD) had obviously seasonal change characteristics. The AOD was higher in spring and summer than that in autumn and winter, and the AOD was the largest in summer. The atmospheric aerosols had significant effects on radiation and micrometeorological factors. With the increase of AOD from 0 to 3, photosynthetically active radiation (PAR) decreased by 43.63%, diffuse radiation increased by 170%, and the fraction of diffuse radiation increased by 2.55 times, while the relative humidity increased by 48.52% and daily temperature difference increased about 3℃. When the ecosystem was under moisture stress, the atmospheric aerosols had no effect on the GPP. When the ecosystem was under non-moisture stress, the LUE and GPP of poplar plantation ecosystem increased first and then decreased with the increase of aerosol concentration. When the AOD was 1.0-1.6, the GPP was maintained at a high level. When the AOD>2.5, the GPP significantly decreased and less than the GPP of the background atmospheric aerosol (AOD<0.4). The path analysis showed that the indirect effect of atmospheric aerosols on ecosystem productivity of poplar plantation was not significant under water stress, the diffuse radiation had the greatest influence on the GPP, and the atmospheric aerosols could increase the ecosystem productivity by increasing diffuse fertilization effect under non-moisture stress. Overall, the atmospheric aerosols had different effects on poplar plantation ecosystem under different water conditions. The suitable atmospheric aerosols could increase the productivity of poplar plantation ecosystems, while severe atmospheric aerosols pollution (AOD>1.5) led to a decrease in poplar ecosystem productivity under non-water stress conditions. 参考文献 相似文献 引证文献

Airborne hyperspectral imaging of nitrogen deficiency on crop traits and yield of maize by machine learning and radiative transfer modeling

Nitrogen is an essential nutrient that directly affects plant photosynthesis, crop yield, and biomass production for bioenergy crops, but excessive application of nitrogen fertilizers can cause environmental degradation. To achieve sustainable nitrogen fertilizer management for precision agriculture, there is an urgent need for nondestructive and high spatial resolution monitoring of crop nitrogen and its allocation to photosynthetic proteins as that changes over time. Here, we used visible to shortwave infrared (400–2400 nm) airborne hyperspectral imaging with high spatial (0.5 m) and spectral (3–5 nm) resolutions to accurately estimate critical crop traits, i.e., nitrogen, chlorophyll, and photosynthetic capacity (CO2-saturated photosynthesis rate, Vmax,27), at leaf and canopy scales, and to assess nitrogen deficiency on crop yield. We conducted three airborne campaigns over a maize (Zea mays L.) field during the growing season of 2019. Physically based soil-canopy Radiative Transfer Modeling (RTM) and data-driven approaches i.e. Partial-Least Squares Regression (PLSR) were used to retrieve crop traits from hyperspectral reflectance, with ground truth of leaf nitrogen, chlorophyll, Vmax,27, Leaf Area Index (LAI), and harvested grain yield. To improve computational efficiency of RTMs, Random Forest (RF) was used to mimic RTM simulations to generate machine learning surrogate models RTM-RF. The results show that prior knowledge of soil background and leaf angle distribution can significantly reduce the ill-posed RTM retrieval. RTM-RF achieved a high accuracy to predict leaf chlorophyll content (R2 = 0.73) and LAI (R2 = 0.75). Meanwhile, PLSR exhibited better accuracy to predict leaf chlorophyll content (R2 = 0.79), nitrogen concentration (R2 = 0.83), nitrogen content (R2 = 0.77), and Vmax,27 (R2 = 0.69) but required measured traits for model training. We also found that canopy structure signals can enhance the use of spectral data to predict nitrogen related photosynthetic traits, as combining RTM-RF LAI and PLSR leaf traits well predicted canopy-level traits (leaf traits × LAI) including canopy chlorophyll (R2 = 0.80), nitrogen (R2 = 0.85) and Vmax,27 (R2 = 0.82). Compared to leaf traits, we further found that canopy-level photosynthetic traits, particularly canopy Vmax,27, have higher correlation with maize grain yield. This study highlights the potential for synergistic use of process-based and data-driven approaches of hyperspectral imaging to quantify crop traits that facilitate precision agricultural management to secure food and bioenergy production.

A new perspective on the inhibition of plant photosynthesis by uranium: decrease of root activity and stomatal closure

Uranium (U) is difficult to be transported from roots to leaves, but it has been reported to inhabit photosynthesis in leaves, so how does this work? In the present study, the effects of U (0–25 μM) on the development and photosynthesis in V. faba seedlings were studied under hydroponics. The results showed that U significantly inhibited the growth and development of V. faba plants, including decreased biomass, water content, lateral root number and root activity. U also led to a large accumulation of reactive oxygen species (ROS) in the leaves which affects leaf structural traits (e.g., decreased leaf area and chlorophyll a content). When U concentration was 25 μM, the net photosynthetic rate (Pn) and transpiration rate (Tr) were inhibited, which were only 66.53% and 41.89% of the control, respectively. Further analysis showed that the stomatal density of leaves increased with the increase of U concentration, while the stomatal aperture and stomatal conductance (Gs) were on the contrary. The results of chlorophyll fluorescence showed that the non-photochemical quenching coefficient (NPQ) increased and the electron transfer rate (ETR) decreased after U exposure, but fortunately, photosystem II (PSII) suffered little damage overall. In conclusion, the accumulation of U in the roots inhibited the root activity, resulting in water shortage in the plants. To prevent water loss, leaves have to regulated stomatal closure at the cost of weakening photosynthesis. These results provide a new insight into the mechanism by which U affects plant photosynthesis.