Unmanned aerial vehicle (UAV) remote sensing technology can be used for fast and efficient monitoring of plant diseases and pests, but these techniques are qualitative expressions of plant diseases. ...However, the yellow leaf disease of arecanut in Hainan Province is similar to a plague, with an incidence rate of up to 90% in severely affected areas, and a qualitative expression is not conducive to the assessment of its severity and yield. Additionally, there exists a clear correlation between the damage caused by plant diseases and pests and the change in the living vegetation volume (LVV). However, the correlation between the severity of the yellow leaf disease of arecanut and LVV must be demonstrated through research. Therefore, this study aims to apply the multispectral data obtained by the UAV along with the high-resolution UAV remote sensing images to obtain five vegetation indexes such as the normalized difference vegetation index (NDVI), optimized soil adjusted vegetation index (OSAVI), leaf chlorophyll index (LCI), green normalized difference vegetation index (GNDVI), and normalized difference red edge (NDRE) index, and establish five algorithm models such as the back-propagation neural network (BPNN), decision tree, naïve Bayes, support vector machine (SVM), and k-nearest-neighbor classification to determine the severity of the yellow leaf disease of arecanut, which is expressed by the proportion of the yellowing area of a single areca crown (in percentage). The traditional qualitative expression of this disease is transformed into the quantitative expression of the yellow leaf disease of arecanut per plant. The results demonstrate that the classification accuracy of the test set of the BPNN algorithm and SVM algorithm is the highest, at 86.57% and 86.30%, respectively. Additionally, the UAV structure from motion technology is used to measure the LVV of a single areca tree and establish a model of the correlation between the LVV and the severity of the yellow leaf disease of arecanut. The results show that the relative root mean square error is between 34.763% and 39.324%. This study presents the novel quantitative expression of the severity of the yellow leaf disease of arecanut, along with the correlation between the LVV of areca and the severity of the yellow leaf disease of arecanut. Significant development is expected in the degree of integration of multispectral software and hardware, observation accuracy, and ease of use of UAVs owing to the rapid progress of spectral sensing technology and the image processing and analysis algorithms.
The nonyellow COLORING 1‐like gene (NOL) is known for its roles in accelerating leaf senescence, but the underlying metabolic mechanisms for heat‐induced leaf senescence remain unclear. The ...objectives of this study were to identify metabolites and associated metabolic pathways regulated by knockdown of NOL in perennial ryegrass (Lolium perenne) and to determine the metabolic mechanisms of NOL controlling heat‐induced leaf senescence. Wild‐type (WT; cv. “Pinnacle”) and two lines (Noli‐1 and Noli‐2) of perennial ryegrass with LpNOL knockdown were exposed to heat stress at 35/33°C (day/night) or nonstress control temperatures at 25/22°C (day/night) for 30 days in growth chambers. Leaf electrolyte leakage, chlorophyll (Chl) content, photochemical efficiency (Fv/Fm), and net photosynthetic rate (Pn) were measured as physiological indicators of leaf senescence, while gas chromatography‐mass spectrometry was performed to identify metabolites regulated by LpNOL. Knockdown of LpNOL suppressed heat‐induced leaf senescence and produced a stay‐green phenotype in perennial ryegrass, as manifested by increased Chl content, photochemical efficiency, net photosynthetic rate, and cell membrane stability in Noli‐1 and Noli‐2. Five metabolites (valine, malic acid, threonic acid, shikimic acid, chlorogenic acid) were uniquely upregulated in LpNOL plants exposed to heat stress, and six metabolites (aspartic acid, glutamic acid, 5‐oxoproline, phenylalanine, proline, tartaric acid) exhibited more pronounced increases in their content in LpNOL plants than the WT. LpNOL could regulate heat‐induced leaf senescence in perennial ryegrass through metabolic reprogramming in the pathways of respiration, secondary metabolism, antioxidant metabolism, and protein synthesis.
Aspartate is the most critical amino acid in the aspartate metabolic pathway, which is associated with multiple metabolic pathways, such as protein synthesis, nucleotide metabolism, TCA cycle, ...glycolysis, and hormone biosynthesis. Aspartate also plays an important role in plant resistance to abiotic stress, such as cold stress, drought stress, salt stress or heavy metal stress. This study found that the chlorophyll content and antioxidant active enzyme content (SOD, CAT, POD and APX) of perennial ryegrass treated with 2 mM aspartate were significantly higher than those treated with water under heat stress. The electrolyte leakage rate, MDA content and peroxide levels (O
and H
O
) of perennial ryegrass treated with aspartate were significantly lower than those of perennial ryegrass treated with water, indicating that exogenous aspartate increases the content of chlorophyll, maintain the integrity of cell membrane system, and enhances SOD-CAT antioxidant pathway to eliminate the oxidative damage caused by ROS in perennial ryegrass under heat stress. Furthermore, exogenous aspartate could enhance the TCA cycle, the metabolism of the amino acids related to the TCA cycle, and pyrimidine metabolism to enhance the heat tolerance of perennial ryegrass.
•The landscape structure was dominated by “sink” landscape in Poyang Lake Basin.•The LWLI was more effective in describing TP loss than were the “source-sink” landscape area structure indices.•The ...modified LWLI could better indicate the coupling relationship between the “source-sink” landscape pattern and phosphorus output across the basin.
Optimizing the landscape structure and spatial configuration of the basin is one of the most important ways to reduce the harm of non-point source pollution (NPSP) to water bodies. The coupling relationship between the “source-sink” landscape pattern and NPSP process had long been a research hotspot of “source-sink” landscape theory. However, the “source-sink” landscape index represented by the classic location-weighted landscape index (LWLI) is suitable only for watersheds with similar environmental backgrounds, and cannot reflect the spatiotemporal heterogeneity of phosphorus output between watersheds with large differences in environmental backgrounds. In this study, 15 tributary watersheds in the Poyang Lake Basin were selected as the case study. The characteristics of “source-sink” landscape structure in 2020 were described by using landscape area structure indices. Moreover, the classical LWLI was modified by adding the topographic wetness index, soil erodibility index and vegetation interception index, and by evaluating the spatiotemporal differences in the effect of “source-sink” landscape patterns on phosphorus export in three hydrological periods (normal, wet and dry) by pearson correlation analysis and redundancy analysis. We found that (1) the proportion of “sink” landscape (greater than 58%) was greater than that of “source” landscape (less than 40%) in all sub-watersheds. In addition, the results of Lorentz curves showed that when the elevation and slope increased, the proportion of “source” landscape decreased and the proportion of “sink” landscape increased. (2) the classical and modified LWLI values were less than 0.5, which indicated that the potential contribution of the “sink” landscape was greater than that of the “source” landscape. (3) The correlation between the classical LWLI and total phosphorus (TP) in the wet period and normal period was stronger than the correlation between all “source-sink” landscape area structure indices and TP, indicating that the LWLI was more effective in describing TP loss than were the “source-sink” landscape area structure indices. (4) the correlation of the modified LWLI with TP in the three periods were stronger than those of the classical LWLI with TP, which indicated that the modified LWLI could better indicate the coupling relationship between the “source-sink” landscape pattern and the phosphorus output by introducing the factors of terrain runoff, soil erodibility and vegetation interception. This study can help with the evaluation of the spatial and temporal heterogeneity of nutrient loss in different watersheds with various landscape patterns, and provide a basis for scientific prevention and control of NPSP.
Invasive fungal diseases are associated with significant morbidity and mortality, particularly in immunocompromised individuals. Early and accurate diagnosis is crucial for effective treatment. ...Despite traditional methods such as microbiological culture, histopathology, radiology and direct microscopy are available, antigen/antibody‐based diagnostics are emerging for diagnosis of invasive fungal infections (IFI). Fungal cell wall is a unique structure composed of polysaccharides that are well correlated with fungal burden during fungal infections. Based on this feature, cell wall polysaccharides have been explored as antigens in IFIs diagnostics such as the galactomannan assay, mannan test, β‐glucan assay and cryptococcal CrAg test. Herein, we provide an overview on the cell wall polysaccharides from three opportunistic pathogens: Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans, and their applications for IFIs diagnosis. The clinical outcome of newly developed cell wall polysaccharides‐based diagnostics is also discussed.
Abstract
The emissions of NO and N
2
O during biological nitrogen removal harm the environment. In this study, a sequencing batch reactor (SBR) was used to treat ammonium-rich organic wastewater. The ...nitrogen transformation and characteristics of NO and N
2
O accumulation in typical cycles under different nitrification conditions were monitored, and the mechanisms of NO and N
2
O production in A/O-SBR were analyzed. The results showed that NO accumulated in the anoxic phase under a fixed concentration of organic carbon source during denitrification with nitrite as electron acceptor or nitrate as electron acceptor. NO production in the aerobic phase could be related to hydroxylamine oxidation and nitrite reduction caused by high ammonia nitrogen. The accumulation of N
2
O mainly occurred in the aerobic phase, and the cumulative concentration of N
2
O at the end of the four typical cycles was above 4.02 mg/L. N
2
O accumulation attributed to the inhibition of free nitrous acid (FNA) and NO, and electronic competition, which made N
2
O reductase (
N
2
OR
) activity insufficient, failing N
2
O reduction.
Abstract
Nitro oxide (NO) and Nitrous oxide (N
2
O) are inevitable intermediates of sulfide autotrophic denitrification (SAD) process, and have huge environmental hazard. This study investigated the ...produce mechanism and accumulation characteristic of NO and N
2
O in SAD process under different S/N ratios. The results showed that the lower S/N ratio, the higher NO accumulation. Which was due to the strong reducing effect of S
2
- and the electronic competition between nitrogen reductase. And under S/N ratio = 2, N
2
O level reached its peak, which was caused by electronic competition. When the S/N ratio = 1, although the electronic competition was more intense, the total amount of electrons was less, thus the N
2
O produced is lower than that produced when S/N=2. Microbial community analysis showed that
Thiobacillus
sp. (62.44%) was the predominant genus, and conducted the suldide-oxiding autotrophic denitrification process.
By using the GPS-X software, the enhanced phosphorus removal (EPR)process was simulated in this study. The comparisons among nitrogen and phosphorus removal efficiency of traditional A2/O process, ...University of Cape Town (UCT) process, Modified University of Cape Town (MUC) process and inverted A2/O process were conducted, in order to determine the best process under the same conditions of construction investment and running cost. The results showed that the simply reversed A2/O process exhibited poor total phosphorus (TP) removal efficiency under low carbon level. The effluent water qualities of the other three processes under low, medium and high levels of carbon source met the first B level criteria in Discharge Standard of Pollutants for Municipal Wastewater Plan (GB18918-2002) for China. The ranges of removal efficiencies of TP, TN, NH4+-N and COD were 63.15% ∼ 94.91%, 55.38% ∼ 77.89%, 96.91% ∼ 97.70% and 90.89% ∼ 93.66%, respectively. Denitrifying phosphorus removal occurred in anoxic tank of EPR process. The phosphorus accumulation concentration was 6.91 mg/L, and the maximum phosphorus released in anaerobic tank was 24.01 mg/L, and the higher P release gave the EPR process a high P removal effiency. Except for the TN which met the first B level criteria (GB18918-2002), TP, NH4+-N and COD met the first A level criteria GB18918-2002), above that, the process was feasible. Inverted A2/O process exhibited the highest nitrogen removal efficiency for its sufficient carbon source in anoxic tank.
α-Ketoglutarate (AKG) is a key intermediate metabolite in the tricarboxylic acid cycle of respiration and a precursor for glutamate, playing important roles in regulating plant growth and stress ...tolerance. The objectives of this study were to examine effects of AKG on heat tolerance characterized by leaf senescence in a cool-season grass species by foliar application and to determine major metabolites and associated metabolic pathways regulated by AKG for its effects on heat tolerance. Perennial ryegrass (Lolium perenne L.) plants were exposed to heat stress (35/30 °C, day/night) or optimal temperature (25/20 °C, day/night, non-stress control) in controlled-environment growth chambers. The solution containing AKG (5 mM) was applied to leaves by spraying 7 d prior to the initiation of heat stress and every 7 d during the heat stress period. Exogenous application of AKG enhanced heat tolerance in perennial ryegrass, as manifested by significant increases in leaf chlorophyll content, photochemical efficiency, and membrane stability, as well as activities of antioxidant enzymes for H2O2 scavenging in AKG-treated plants relative to untreated control plants exposed to heat stress. Metabolic profiling and pathway analysis demonstrated that exogenous AKG application enhanced metabolite accumulation in four major metabolic pathways, including antioxidant metabolism, amino acid metabolism, glycolysis and tricarboxylic acid cycle of respiration, and pyrimidine metabolism, contributing to AKG-improved heat tolerance in perennial ryegrass.
•α-Ketoglutarate (AKG) enhanced heat tolerance in perennial ryegrass.•AKG suppressed heat-induced leaf senescence.•AKG regulated the metabolism of antioxidant, amino acids, pyrimidine, glycolysis, and TCA cycle of respiration.
Introduction
Rubber trees are an important cash crop in Hainan Province; thus, monitoring sample plots of these trees provides important data for determining growth conditions. However, existing ...monitoring technology and rubber forest sample plot analysis methods are relatively simple and present widespread issues, such as limited monitoring equipment, transportation difficulties, and relatively poor three-dimensional visualization effects in complex environments. These limitations have complicated the development of rubber forest sample plot monitoring.
Method
This study developed a terrestrial photogrammetry system combined with 3D point-cloud reconstruction technology based on the structure from motion with multi-view stereo method and sample plot survey data. Deviation analyses and accuracy evaluations of sample plot information were performed in the study area for trees to explore the practical significance of this method for monitoring rubber forest sample plots. Furthermore, the relationship between the height of the first branch, diameter at breast height (DBH), and rubber tree volume was explored, and a rubber tree standard volume model was established.
Results
The Bias, relative Bias, RMSE, and RRMSE of the height of the first branch measured by this method were −0.018 m, −0.371%, 0.562 m, and 11.573%, respectively. The Bias, relative Bias, RMSE, and RRMSE of DBH were −0.484 cm, −1.943%, −2.454 cm, and 9.859%, respectively, which proved that the method had high monitoring accuracy and met the monitoring requirements of rubber forest sample plots. The fitting results of rubber tree standard volume model had an R
2
value of 0.541, and the estimated values of each parameter were 1.745, 0.115, and 0.714. The standard volume model accurately estimated the volume of rubber trees and forests using the first branch height and DBH.
Discussion
This study proposed an innovative planning scheme for a terrestrial photogrammetry system for 3D visual monitoring of rubber tree forests, thus providing a novel solution to issues observed in current sample plot monitoring practices. In the future, the application of terrestrial photogrammetry systems to monitor other types of forests will be explored.
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