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1.
Plant Genome ; 13(1): e20001, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-33016624

RESUMO

African wild rice Oryza longistaminata, one of the eight AA- genome species in the genus Oryza, possesses highly valued traits, such as the rhizomatousness for perennial rice breeding, strong tolerance to biotic and abiotic stresses, and high biomass production on poor soils. To obtain the high-quality reference genome for O. longistaminata we employed a hybrid assembly approach through incorporating Illumina and PacBio sequencing datasets. The final genome assembly comprised only 107 scaffolds and was approximately ∼363.5 Mb, representing ∼92.7% of the estimated African wild rice genome (∼392 Mb). The N50 lengths of the assembled contigs and scaffolds were ∼46.49 Kb and ∼6.83 Mb, indicating ∼3.72-fold and ∼18.8-fold improvement in length compared to the earlier released assembly (∼12.5 Kb and 364 Kb, respectively). Aided with Hi-C data and syntenic relationship with O. sativa, these assembled scaffolds were anchored into 12 pseudo-chromosomes. Genome annotation and comparative genomic analysis reveal that lineage-specific expansion of gene families that respond to biotic- and abiotic stresses are of great potential for mining novel alleles to overcome major diseases and abiotic adaptation in rice breeding programs. This reference genome of African wild rice will greatly enlarge the existing database of rice genome resources and unquestionably form a solid base to understand genomic basis underlying highly valued phenotypic traits and search for novel gene sources in O. longistaminata for the future rice breeding programs.


Assuntos
Oryza , Genoma , Genômica , Oryza/genética , Análise de Sequência de DNA
2.
Plant Genome ; 13(1): e20005, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-33016626

RESUMO

A genome-wide association study (GWAS) needs to have a suitable population. The factors that affect a GWAS (e.g. population structure, sample size, and sequence analysis and field testing costs) need to be considered. Mixed populations containing subpopulations of different genetic backgrounds may be suitable populations. We conducted simulation experiments to see if a population with high genetic diversity, such as a diversity panel, should be added to a target population, especially when the target population harbors small genetic diversity. The target population was 112 accessions of Oryza sativa L. subsp. japonica, mainly developed in Japan. We combined the target population with three populations that had higher genetic diversity. These were 100 indica accessions, 100 japonica accessions, and 100 accessions with various genetic backgrounds. The results showed that the GWAS's power with a mixed population was generally higher than with a separate population. Also, the optimal GWAS populations varied depending on the fixation index (FST ) of the quantitative trait nucleotides (QTNs) and the polymorphism of QTNs in each population. When a QTN was polymorphic in a target population, a target population combined with a higher diversity population improved the QTN's detection power. By investigating FST and the expected heterozygosity (He ) as factors influencing the detection power, we showed that single nucleotide polymorphisms with high FST or low He are less likely to be detected by GWAS with mixed populations. Sequenced or genotyped germplasm collections can improve the GWAS's detection power by using a subset of the collections with a target population.


Assuntos
Oryza , Estudo de Associação Genômica Ampla , Genótipo , Japão , Oryza/genética , Polimorfismo de Nucleotídeo Único
3.
Science ; 369(6508): 1161-1162, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32883847

Assuntos
Oryza , Solo , Ecossistema , Silício
4.
Sci Total Environ ; 740: 140403, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32927559

RESUMO

Waste amendments, such as steel slag and biochar, have been reported as a strategy for improving soil fertility, crop productivity, and carbon (C) sequestration in agricultural lands. However, information regarding the subsequent effects of steel slag and biochar on C cycling and the underlying microbial mechanisms in paddy soils remains limited. Hence, this study aimed to examine the effect of these waste amendments (applied in 2015-2017) on total soil CO2 emissions, total and active soil organic C (SOC) contents, and microbial communities in the early and late seasons in a subtropical paddy field. The results showed that despite the exogenous C input from these waste amendments (steel slag, biochar and slag + biochar), they significantly (P < 0.05) decreased total CO2 emissions (e.g., by 41.9-59.6% at the early season), compared to the control soil. These amendments also significantly (P < 0.001) increased soil salinity and pH. The increased soil pH had a negative effect (r = -0.37, P < 0.05) on microbial biomass C (MBC). The biochar and slag + biochar treatments (cf. control) significantly (P < 0.001) increased SOC contents in the both seasons. The amendments altered the soil microbial community structure that associated with soil C cycling: (1) all three amendments increased the relative abundance of Agromyces and Streptomyces, which was associated with higher soil pH (cf. control); and (2) biochar and slag + biochar treatments caused a higher relative abundance of Sphingomonas, which was supported by high SOC contents under those amendments. Overall, this study demonstrated that the steel slag and biochar amendments altered microbial community composition due to changes in key soil properties, such as salinity, pH and SOC contents, with implications for increasing soil C stocks while mitigating CO2 emissions in the paddy field.


Assuntos
Oryza , Solo , Dióxido de Carbono/análise , Carvão Vegetal , Microbiologia do Solo , Aço
5.
PLoS Pathog ; 16(8): e1008801, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866183

RESUMO

Rice stripe virus (RSV) is one of the most destructive viral diseases affecting rice production. However, so far, only one RSV resistance gene has been cloned, the molecular mechanisms underlying host-RSV interaction are still poorly understood. Here, we show that increasing levels or signaling of brassinosteroids (BR) and jasmonic acid (JA) can significantly enhance the resistance against RSV. On the contrary, plants impaired in BR or JA signaling are more susceptible to RSV. Moreover, the enhancement of RSV resistance conferred by BR is impaired in OsMYC2 (a key positive regulator of JA response) knockout plants, suggesting that BR-mediated RSV resistance requires active JA pathway. In addition, we found that RSV infection suppresses the endogenous BR levels to increase the accumulation of OsGSK2, a key negative regulator of BR signaling. OsGSK2 physically interacts with OsMYC2, resulting in the degradation of OsMYC2 by phosphorylation and reduces JA-mediated defense to facilitate virus infection. These findings not only reveal a novel molecular mechanism mediating the crosstalk between BR and JA in response to virus infection and deepen our understanding about the interaction of virus and plants, but also suggest new effective means of breeding RSV resistant crops using genetic engineering.


Assuntos
Brassinosteroides/metabolismo , Ciclopentanos/metabolismo , Oryza , Oxilipinas/metabolismo , Plantas Geneticamente Modificadas , Transdução de Sinais , Tenuivirus , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Oryza/genética , Oryza/metabolismo , Oryza/virologia , Doenças das Plantas/genética , Doenças das Plantas/virologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/virologia , Tenuivirus/genética , Tenuivirus/metabolismo
6.
Ecotoxicol Environ Saf ; 203: 111054, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888616

RESUMO

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%-30%.


Assuntos
Antioxidantes/metabolismo , Ferro/toxicidade , Nanopartículas/toxicidade , Oryza/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Quinolinas/toxicidade , Poluentes do Solo/toxicidade , Transporte Biológico , Biomassa , Clorofila/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
7.
Chemosphere ; 254: 126799, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957268

RESUMO

Enrichment of cadmium (Cd) during weathering and pedogenesis of carbonate rocks has resulted in large areas of lands with soil Cd concentrations exceeding the official guidelines in China and other countries. However, it is reported in many studies that the risk of soil contamination by Cd from this natural process can be neglected as most of the Cd is not bioavailable. Noticing that the previous studies focused only on eluvial areas but not on lowland alluvium, where Cd from the eluvial areas can be transported and accumulated, we selected the Qingyang county in Anhui province, where there are two small drainage basins developed wholly on carbonate bedrock, to compare the Cd speciation and activity between eluvium and alluvium, and to evaluate the risk of Cd pollution to the latter. By the application of systematic sampling and analysis of the bedrock, soil, and rice grain samples, and in comparison with the previously acknowledged "high background with low mobility" area in Guizhou, it was found that soil developed from alluvium has both higher total Cd and higher mobile Cd proportion than soil from the upland eluvium. A very high percentage of rice grain samples (51%) grown on the alluvial soil exceeded the food standard for Cd (0.2 mg kg-1). Therefore, the spatial division of alluvium and eluvium should be the first step in the assessment of the Cd risk in carbonate regions, and special attention should be given to soil developed from alluvium.


Assuntos
Cádmio/análise , Poluentes do Solo/análise , Carbonatos/análise , China , Poluição Ambiental/análise , Poluição Ambiental/estatística & dados numéricos , Oryza , Solo , Tempo (Meteorologia)
8.
Pestic Biochem Physiol ; 170: 104695, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32980058

RESUMO

In this study, thirty 1,3,4-oxadiazole sulfone derivatives containing 3,4-dichloroisothiazolamide moiety were designed and synthesized, and their antibacterial activities were evaluated. Bioassay results showed that some compounds exhibited excellent antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) in vitro and in vivo. Notably, the EC50 values of compounds 2 and 3 against Xoo were 0.79 and 0.85 µg/mL, respectively, which were superior to those of the control agents isotianil, bismerthiazol, and thiodiazole copper. In addition, in vivo antibacterial activities revealed that the compound 2 at 50 µg/mL possessed protective and curative activities of 43.99% and 41.06% against Xoo, respectively, which were better than positive controls. Furthermore, the preliminary mechanism study disclosed that compound 2 exhibited effective antibacterial activity against Xoo by inhibiting the formation of extracellular polysaccharides from Xoo, increasing cell permeability, and changing the shape of cells. This study suggested that 1,3,4-oxadiazole sulfone derivatives containing 3,4-dichloroisothiazolamide moiety displayed excellent antibacterial activity and could be further explored and developed as commercial pesticides.


Assuntos
Oryza , Xanthomonas , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana , Oxidiazóis , Doenças das Plantas , Sulfonas/farmacologia
9.
Pestic Biochem Physiol ; 170: 104681, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32980063

RESUMO

Chitosan oligosaccharides (COS) can elicit plant immunity and defence responses in rice plants, but exactly how this promotes plant growth remains largely unknown. Herein, we explored the effects of 0.5 mg/L COS on plant growth promotion in rice seedlings by measuring root and stem length, investigating biochemical factors in whole plants via proteomic analysis, and confirming upregulated and downregulated genes by real-time quantitative PCR. Pathway enrichment results showed that COS promoted root and stem growth, and stimulated metabolic (biosynthetic and catabolic processes) and photosynthesis in rice plants during the seedling stage. Expression levels of genes related to chlorophyll a-b binding, RNA binding, catabolic processes and calcium ion binding were upregulated following COS treatment. Furthermore, comparative analysis indicated that numerous proteins involved in the biosynthesis, metabolic (catabolic) processes and photosynthesis pathways were upregulated. The findings indicate that COS may upregulate calcium ion binding, photosynthesis, RNA binding, and catabolism proteins associated with plant growth during the rice seedling stage.


Assuntos
Quitosana , Oryza/genética , Clorofila A , Regulação da Expressão Gênica de Plantas , Oligossacarídeos , Proteínas de Plantas/genética , Proteômica , Plântula/genética
10.
Ecotoxicol Environ Saf ; 203: 110990, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888601

RESUMO

The presence of sulfamethoxazole (SMX) in croplands has become an international concern. The environmental behavior and fate of SMX in agricultural soils are not well understood, especially when the adsorption behavior is disturbed by the dissolved organic matter (DOM) released by crop straw. As canola straw is one of the biomasses widely returned to farmlands, we characterized DOM derived from pristine and decomposed canola straw, and explored the effects and mechanisms of the DOMs on regulating SMX adsorption to purple paddy soils. The spectral analysis showed that the molecular weight, aromaticity, and hydrophobicity of canola straw-derived DOM increased as decomposition proceeded. These physicochemical properties collectively determined the effects of the DOM on SMX adsorption. The DOM derived from pristine canola straw increased SMX maximum adsorption capacity of the soils by approximately 2.6 times, but this positive effect gradually decreased to a steady state by day 90 in the straw decomposition period. Nevertheless, the SMX adsorption behavior in the soils was invariably determined by the DOM extracts. These adsorption processes of SMX were well fitted by the double-chamber kinetics model and the Langmuir and Freundlich thermodynamic models. Thermodynamic parameters indicated that SMX adsorption onto the soils was spontaneous and endothermic, and this adsorption characteristics was not significantly (p > 0.05) changed by the DOM extracts. However, the adsorption kinetics were altered by those DOMs, i.e., the fast and slow adsorption processes were both diminished. Correspondingly, co-adsorption and cumulative adsorption were identified as the main mechanisms determining SMX adsorption to the purple paddy soils in the presence of the straw-derived DOMs. These results collectively indicated that the DOMs released by straw in croplands may decrease the ecological risks of organic pollutants by inhibiting their migration processes.


Assuntos
Brassica/química , Poluentes do Solo/química , Solo/química , Sulfametoxazol/química , Adsorção , Agricultura , Oryza/crescimento & desenvolvimento , Silagem
11.
Bull Environ Contam Toxicol ; 105(4): 572-581, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32960333

RESUMO

In order to assess the environmental impacts caused by flood to the paddy field, 940 semi-volatile organic compounds (SVOCs) were screened in paddy soil samples taken in central Vietnam before and after flooding. The concentration of 166 SVOCs in soil samples ranged from 0.031 to 2241 (mean 89.1) µg kg-1 dry wt. Chemicals originating from household sources showed the highest level, followed by chemicals originating from agriculture. Since untreated domestic wastewater used for agricultural irrigation, organic micro-pollutants in domestic wastewater is the main source of pollutants in paddy soil. However, contamination levels of pollutants in paddy soil after flooding were lower than those before flooding, possibly due to the removal of pollutants by floodwater. As a result, pollution characteristic of pollutants at sampling locations were different before flooding while they became similar after flooding due to the dispersion and elution of organic pollutants from soil into floodwaters.


Assuntos
Monitoramento Ambiental , Inundações , Compostos Orgânicos/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Oryza/crescimento & desenvolvimento , Solo/química , Vietnã
12.
Chemosphere ; 254: 126881, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957288

RESUMO

Application of biochar (BC) derived from rice straw has generated increasing interest in long-term storage of soil organic carbon (SOC), however its carbon (C) sequestration potential vary widely among agricultural soils despite the same BC dose used. These discrepancies in the ability of soils to sequester C after BC application are poorly understood. Metabolic quotient (qCO2) is a reflection of "microbial efficiency" and linked to SOC turnover across ecosystems. Therefore, we investigated the SOC sequestration and qCO2 in a Yellow River alluvium paddy soil (YP) and a quaternary red clay paddy soil (QP) under rice-wheat annual rotation following 4-year of BC application rate of 11.3 Mg ha-1 per cropping season. BC application consistently brought 65.3 Mg C ha-1 into the soils over 4-year experimental period but increased SOC by 57.6 Mg C ha-1 in YP and 64.5 Mg C ha-1 in QP. Calculating SOC mass balance showed 11.7% of BC-C losses from YP and only 1.16% from QP. BC application stimulated the G+ bacterial, fungi, and actinomycetes by increasing O-alkyl C content in YP, while decreased the same microorganisms by decreasing anomeric C-H content in QP. Importantly, higher clay and amorphous Fe (Feo) contents in QP after BC application protected SOC from further decomposition, which in turn decreased microorganisms and resulted in higher SOC sequestration than YP. Our results indicated that soil properties controlled the extent of SOC sequestration after BC application and site-specific soil properties must be carefully considered to maximize long-term SOC sequestration after BC application.


Assuntos
Agricultura/métodos , Sequestro de Carbono , Carvão Vegetal/química , Carbono/metabolismo , Argila , Ecossistema , Oryza/metabolismo , Solo/química
13.
Nat Commun ; 11(1): 4778, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963241

RESUMO

Obtaining genetic variation information from indica rice hybrid parents and identification of loci associated with heterosis are important for hybrid rice breeding. Here, we resequence 1,143 indica accessions mostly selected from the parents of superior hybrid rice cultivars of China, identify genetic variations, and perform kinship analysis. We find different hybrid rice crossing patterns between 3- and 2-line superior hybrid lines. By calculating frequencies of parental variation differences (FPVDs), a more direct approach for studying rice heterosis, we identify loci that are linked to heterosis, which include 98 in superior 3-line hybrids and 36 in superior 2-line hybrids. As a proof of concept, we find two accessions harboring a deletion in OsNramp5, a previously reported gene functioning in cadmium absorption, which can be used to mitigate rice grain cadmium levels through hybrid breeding. Resource of indica rice genetic variation reported in this study will be valuable to geneticists and breeders.


Assuntos
Variação Genética , Vigor Híbrido/genética , Oryza/genética , Cruzamento , Proteínas de Transporte de Cátions/genética , China , Cruzamentos Genéticos , Deleção de Genes , Genes de Plantas , Hibridização Genética , Oryza/classificação , Filogenia , Proteínas de Plantas/genética , Polimorfismo de Nucleotídeo Único
14.
Medicine (Baltimore) ; 99(31): e21165, 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32756094

RESUMO

GOALS: The aim of this study was to evaluate the effectiveness of adding a gelling agent to pureed diets to prevent aspiration pneumonia in elderly patients with moderate to severe dysphagia. BACKGROUND: Pureed diets are often used to reduce aspiration in patients with dysphagia. However, the ideal texture of a pureed diet to prevent aspiration pneumonia remains unclear. MATERIALS AND METHODS: We prospectively conducted a randomized, crossover trial of pureed rice with or without a gelling agent in patients with moderate to severe dysphagia (ClincialTrials.gov number, NCT03163355). The primary outcome measure was pharyngeal residuals using an endoscopic scoring system. The secondary outcome was the sense of material remaining in the throat following swallowing. RESULTS: Sixty two patients (58% men), mean age 83 ±â€Š9 years with moderate to severe dysphagia were included. Residuals in the throat were significantly less likely with pureed rice with than without the gelling agent (median cyclic ingestion score (range); 1 (0-4) vs 2 (0-4); P = .001). Irrespective of the presence or absence of the gelling agent, the sense of material remaining in the throat was significantly less frequent in older patients (87 ±â€Š7.6 vs 75 ±â€Š9.1 years, P < .01; 86 ±â€Š7.3 vs 75 ±â€Š8.6 years, P < .01). CONCLUSIONS: Pureed diets containing a gelling agent may reduce the risk of aspiration pneumonia possibly by decreasing pharyngeal residues in elderly patients with moderate to severe dysphagia.


Assuntos
Transtornos de Deglutição/dietoterapia , Deglutição , Idoso Fragilizado , Géis/administração & dosagem , Oryza , Pneumonia Aspirativa/prevenção & controle , Idoso de 80 Anos ou mais , Estudos Cross-Over , Dieta , Feminino , Humanos , Masculino , Resultado do Tratamento
15.
Ecotoxicol Environ Saf ; 202: 110950, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800226

RESUMO

Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.


Assuntos
Produção Agrícola/métodos , Monitoramento Ambiental/métodos , Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/efeitos dos fármacos , Poluentes do Solo/análise , Fertilizantes/análise , Humanos , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química , Poluentes do Solo/metabolismo
16.
J Environ Manage ; 271: 111001, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778287

RESUMO

In topsoils, the activity concentrations of natural radionuclides (hereafter NRs) increase due to the addition of NRs from fertilizers, irrigation water, and air dust pollution. On the other hand, various physical-chemical and environmental processes such as radioactive decay, volatilization, leaching, erosion, and plant uptake were responsible for the decrease of the activity concentrations of NRs in the topsoils. In this study, behaviours of 40K, 210Pb, 226Ra, 238U, and 232Th in topsoils were modelled by the CEMC soil model and the HYDRUS-1D model. An exponential equation was proposed for estimating the accumulation rates of these radionuclides in the topsoils. Long-term accumulation of radionuclides was assessed for water spinach (Ipomoea Aquatica Forssk.) soil (hereafter VES) and rice (Oryza sativa L.) soil (hereafter RIS). We found that the current agricultural practices caused the increase of 40K activity concentration in the water spinach soil, and 40K, 210Pb, 226Ra, and 232Th activity concentrations in the rice soil. The accumulation rates of radionuclides were in the order 238U < 232Th < 226Ra < 210Pb < 40K. 25 years of cultivation with water spinach can increase/decrease + (165 ± 6) Bq of 40K, - (8.2 ± 0.7) Bq of 210Pb, - (4.3 ± 0.2) Bq of 226Ra, - (7 0.3 ± 0.3) Bq of 238U, and - (1.8 ± 0.1) Bq of 232Th in 1 kg soil. For rice cultivation, these values are + (1004 ± 39), + (3.3 ± 0.2), + (3.0 ± 0.2), - (5.1 ± 0.3), (2.2 ± 0.1) Bq kg-1 for 40K, 210Pb, 226Ra, 238U, and 232Th, respectively.


Assuntos
Ipomoea , Oryza , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Chumbo , Radioisótopos/análise , Spinacia oleracea , Vietnã , Água
17.
J Environ Manage ; 271: 111029, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778309

RESUMO

Biochar has been widely applied to paddy fields to improve soil fertility, crop productivity and carbon sequestration, thereby leading to variations in the CO2 exchange between the paddy fields under flooding irrigation and the atmosphere, as indicated by many previous reports. However, few relevant reports have focused on paddy fields under water-saving irrigation. This study conducted a field experiment to investigate the effects of three biochar addition rates (0, 20 and 40 t ha-1) on the CO2 exchange between paddy fields under controlled irrigation (CI, a water-saving irrigation technique) and the atmosphere in the Taihu Lake region of Southeast China. Our results showed that biochar addition increased the paddy field ecosystem respiration (Reco) and the soil respiration rate (Rs) in the CI paddy fields. And biochar application increased the total CO2 emissions and the total soil CO2 emissions, especially at a rate of 40 t ha-1. In contrast, gross primary productivity (GPP) was decreased and the net ecosystem exchange of CO2 (NEE) was increased with biochar addition. However, biochar addition at a rate of 20 t ha-1 significantly increased the total CO2 absorption and the net CO2 absorption of the CI paddy fields (p < 0.05), whereas biochar addition at a rate of 40 t ha-1 had no effect on the total CO2 absorption and decreased the total net CO2 absorption. At the same time, biochar addition significantly increased soil catalase, invertase and urease activities and contributed substantially to the increase in soil invertase activity. In addition, the soil bacterial, fungal and actinomycetal abundances were evidently increased with biochar addition, of which the soil fungal abundance showed the greatest increase. A high correlation was observed between soil catalase and invertase activities and soil microbial abundance. Reco was highly correlated with air and soil temperatures and soil enzyme activity. A significant quadratic polynomial correlation was observed between GPP and leaf area index (p < 0.01). The combination of biochar addition at a rate of 20 t ha-1 and water-saving irrigation has the potential to increase the size of the carbon sink and promote soil enzyme and microbial activities in paddy field ecosystems.


Assuntos
Oryza , Água , Agricultura , Dióxido de Carbono/análise , Carvão Vegetal , China , Ecossistema , Solo
18.
Sci Total Environ ; 738: 139832, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806361

RESUMO

Labile soil Cd is susceptible to changes over space and time due to the physical and chemical properties of the soil as well as biological processes. In this study, non-disruptive, in situ monitoring was used to explore these changes. We analyzed the mechanism(s) by which Cd is morphologically transformed and its migration patterns, with the goal of preventing soil Cd from becoming labile. The results showed that the concentration of labile Cd in the soil exhibited spatiotemporal variability throughout the rice growth period. Over time, it increased and then declined, while over space, the concentration of labile Cd in rhizosphere is higher than that in non-rhizosphere. As the depth increased, the concentration of Cd increased and then declined, especially during the flowering stage. The change of soil labile Cd concentration showed significant negative correlation with the change in soil pH and easy dynamic S(II) and Fe(II) content. It was also found that root action changed the pH of the soil during rice growth, thereby affecting the morphologies of S(II) and Fe(II), which governed the transformation of Cd and its soil mobility.


Assuntos
Oryza , Poluentes do Solo/análise , Cádmio/análise , Rizosfera , Solo
19.
Environ Pollut ; 265(Pt B): 115029, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806453

RESUMO

Environmental complexity leads to differences in the spatial distribution of heavy metal pollution in soil and rice. Such spatial differences will seriously affect the safety of planted rice and can impact regional management and control. How to scientifically reveal these spatial differences is an urgent problem. In this study, the spatial mismatch relationship between Cd pollution in soil and rice grains (brown rice) was first explored by the interpolation method. To further reveal the causes of these, the specific recognition rules of the spatial relationship of Cd pollution were extracted based on a decision tree model, and the results were mapped. The results revealed a spatial mismatch in Cd pollution between the soil and rice grains in the study area, and the main results are as follows: (i) slight soil pollution and safe rice accounted for 68.88% of the area; (ii) slight soil pollution and serious rice pollution accounted for 13.39% of the area and (iii) safe soil and serious rice pollution accounted for 11.63% of the area. In addition, 11 recognition rules of Cd spatial pollution relationship between soil and rice were proposed, and the main environmental factors were determined: SOM (soil organic matter), Dis-residence (distance from residential area), soil pH and LAI (leaf area index). The average accuracy of rule recognition was 75.90%. The study reveals the spatial mismatch of heavy metal pollution in soil and crops, providing decision-making references for the spatial accurate identification and targeted prevention of heavy metal pollution spaces.


Assuntos
Oryza , Poluentes do Solo/análise , Cádmio/análise , Árvores de Decisões , Monitoramento Ambiental , Poluição Ambiental/análise , Solo
20.
Bull Environ Contam Toxicol ; 105(2): 283-290, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32734360

RESUMO

The current study investigated the efficiency of sepiolite (SE), sodium humate (HS), microbial fertilizer (JF) and SE combined with JF/HS in a ratio of 2:1 (w/w) (JF-2SE and HS-2SE) on Cd, Pb and As bioavailability in field trials with rice (Oryza sativa L.). The results showed that all the amendments remarkably decreased (p < 0.05) the contents of available Cd and available Pb in soil. Only JF-2SE treatment reduced available As concentration in soil. All the amendments were found to effectively reduce (p < 0.05) the contents of As in brown rice. Both JF-2SE and HS-2SE co-applications reduced the concentrations of Cd in brown rice to 0.108 and 0.135 mg kg-1, and that of Pb reduced to 0.2 and 0.175 mg kg-1, which met the national standard limit of China. Thus, the co-application of JF/HS-2SE can be a promising remediation strategy in Cd, Pb and As co-contaminated paddy soil.


Assuntos
Cádmio/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Disponibilidade Biológica , Cádmio/análise , China , Poluição Ambiental , Fertilizantes , Chumbo/análise , Silicatos de Magnésio , Oryza , Solo/química , Poluentes do Solo/análise
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