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1.
J Agric Food Chem ; 67(35): 9772-9781, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398019

RESUMO

This study aims to investigate the response profiles of vitamin E and carotenoids on transcription and metabolic levels of sweet corn seedlings under temperature stress. The treated temperatures were set as 10 °C (low temperature, LT), 25 °C (control, CK), and 40 °C (high temperature, HT) for sweet corn seedlings. The gene expression profiles of vitamin E and carotenoids biosynthesis pathways were analyzed by real time quantitative polymerase chain reaction (RT-qPCR), and the composition profiles were analyzed by high performance liquid chromatography (HPLC). Results showed that vitamin E gradually accumulated in response to LT stress but was limited by HT stress. The increase of carotenoids was suppressed by LT stress whereas HT stress promoted it. The existing results elaborated the interactive and competitive relationships of vitamin E and carotenoids in sweet corn seedlings to respond to extreme temperature stress at transcriptional and metabolic levels. The present study would improve sweet corn temperature resilience with integrative knowledge in the future.


Assuntos
Carotenoides/metabolismo , Vitamina E/metabolismo , Zea mays/metabolismo , Carotenoides/análise , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/química , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Estresse Fisiológico , Temperatura Ambiente , Vitamina E/análise , Zea mays/química , Zea mays/genética , Zea mays/crescimento & desenvolvimento
2.
World J Microbiol Biotechnol ; 35(8): 126, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363938

RESUMO

Isolation and identification of temperature tolerant phosphate solubilizing bacteria (TTPSB) and their use as microbial fertilizers was the main goal of the study. In this study, TTPSB were isolated from soil samples treated for 16 h at 55 °C. Their phosphate solubilizing activity was either evaluated in solid media by forming a clear zone (halo) or in liquid media by quantification of the soluble phosphate in the growth medium. Five colonies (RPS4, RPS6, RPS7, RPS8 and RPS9) were identified to be able to form a halo and two of the isolates (RPS9 and RPS7) tolerated a temperature of 55 °C. With tricalcium phosphate (TCP) as the sole P-source, the phosphate solubilizing capacity of RPS9 and RPS7 was determined to be 563.8 and 324.1 mg P L-1 in liquid Sperber medium, respectively. Both bacterial isolates were identified as Pantoea agglomerans by molecular and biochemical characterization. To be used as a microbial fertilizer a carrier system for the temperature tolerant bacteria consisting of rock phosphate, sulfur and bagasse was used. It could be established that the bacterial cell counts of the microbial fertilizers were acceptable for application after storage for 4 months at 28 °C. In a greenhouse experiment using pot cultures, inoculation of maize (S.C.704) with the microbial fertilizers in an autoclaved soil resulted in a significant effect on total fresh and dry weight of the plant root and shoot as well as on the P content of the root and shoot. The effects observed with RPS9 as a component of the microbial fertilizer on plant growth and P nutrition was comparable with the addition of 50% of recommended triple superphosphate (TSP) dose. Using temperature tolerant bacteria in microbial fertilizers will overcome limitations in production and storage of the microbial fertilizers and contribute to a environmentally-friendly agriculture. The temperature tolerant P. agglomerans strain RPS9 was shown to be effective as part of a microbial fertilizer in supporting the growth and P uptake in maize.


Assuntos
Agricultura/métodos , Fosfatos de Cálcio/metabolismo , Pantoea/isolamento & purificação , Pantoea/metabolismo , Microbiologia do Solo , Zea mays/crescimento & desenvolvimento , Técnicas Bacteriológicas , Biotransformação , Fosfatos de Cálcio/química , Meios de Cultura/química , Temperatura Alta , Pantoea/classificação , Pantoea/efeitos da radiação , Solubilidade , Zea mays/microbiologia
3.
BMC Plant Biol ; 19(1): 335, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31370805

RESUMO

BACKGROUND: Drought is a serious causal factor of reduced crop yields than any other abiotic stresses. As one of the most widely distributed crops, maize plants frequently suffer from drought stress, which causes great losses in the final kernel yield. Drought stress response in plants showed tissue- and developmental stage-specific characteristics. RESULTS: In this study, the ears at the V9 stage, kernels and ear leaf at the 5DAP (days after pollination) stage of maize were used for morphological, physiological and comparative transcriptomics analysis to understand the different features of "sink" or "source" organs and the effects on kernel yield under drought stress conditions. The ABA-, NAC-mediate signaling pathway, osmotic protective substance synthesis and protein folding response were identified as common drought stress response in the three organs. Tissue-specific drought stress responses and the regulators were identified, they were highly correlated with growth, physiological adaptation and yield loss under drought stress. For ears, drought stress inhibited ear elongation, led to the abnormal differentiation of the paired spikelet, and auxin signaling involved in the regulation of cell division and growth and primordium development changes. In the kernels, reduced kernel size caused by drought stress was observed, and the obvious differences of auxin, BR and cytokine signaling transduction appeared, which indicated the modification in carbohydrate metabolism, cell differentiation and growth retardation. For the ear leaf, dramatically and synergistically reduced the expression of photosynthesis genes were observed when suffered from drought stress, the ABA- and NAC- mediate signaling pathway played important roles in the regulation of photosynthesis. CONCLUSIONS: Transcriptomic changes caused by drought were highly correlated with developmental and physiological adaptation, which was closely related to the final yield of maize, and a sketch of tissue- and developmental stage-specific responses to drought stress in maize was drafted.


Assuntos
Zea mays/fisiologia , Produção Agrícola , Desidratação , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/fisiologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/fisiologia , Fotossíntese , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
4.
World J Microbiol Biotechnol ; 35(8): 129, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31376017

RESUMO

Metal whole-cell biosensors (WCBs) have been reported as very useful tools to detect and quantify the presence of bioavailable fractions of certain metals in water and soil samples. In the current work, two bacterial WCBs able to report Cr(VI) presence and plants growing on Cr(VI)-enriched soil/medium were used to assess the potential transfer of this metal to organisms of higher trophic levels, and the risk of transfer to the food chain. To do it, the functionality of the WCBs within tissues of inoculated plants in contact with Cr(VI)-contaminated soil and water was studied in vitro and in a controlled greenhouse environment. One WCB was the previously described Ochrobactrum tritici pCHRGFP2 and the second, Nitrospirillum amazonense pCHRGFP2, is a newly engineered naturally-occurring endophytic microorganism. Three rice varieties (IAC 4440, BRS 6 CHUÍ, IRGA 425) and one maize variety (1060) were tested as hosts and subjected to Cr(VI) treatments (25 µM), with different results obtained. Inoculation of each WCB into plants exposed to Cr(VI) showed GFP expression within plant tissues. WCBs penetrated the root tissues and later colonized the shoots and leaves. In general, a higher fluorescence signal was detected in roots, together with a higher Cr content and denser WCB colonization. Best fluorescence intensities per plant biomass of shoots were obtained for plant host IRGA 425. Therefore, by analyzing colonized tissues, both WCBs allowed the detection of Cr(VI) contamination in soils and its transfer to plants commonly used in crops for human diet.


Assuntos
Técnicas Biossensoriais/métodos , Cromo/análise , Ochrobactrum/crescimento & desenvolvimento , Oryza/química , Rhodospirillaceae/crescimento & desenvolvimento , Zea mays/química , Disponibilidade Biológica , Engenharia Metabólica , Microscopia de Fluorescência , Ochrobactrum/genética , Ochrobactrum/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Rhodospirillaceae/genética , Rhodospirillaceae/metabolismo , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
5.
BMC Plant Biol ; 19(1): 318, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31311506

RESUMO

BACKGROUND: Single Nucleotide Polymorphism (SNP) array and re-sequencing technologies have different properties (e.g. calling rate, minor allele frequency profile) and drawbacks (e.g. ascertainment bias). This lead us to study their complementarity and the consequences of using them separately or combined in diversity analyses and Genome-Wide Association Studies (GWAS). We performed GWAS on three traits (grain yield, plant height and male flowering time) measured in 22 environments on a panel of 247 F1 hybrids obtained by crossing 247 diverse dent maize inbred lines with a same flint line. The 247 lines were genotyped using three genotyping technologies (Genotyping-By-Sequencing, Illumina Infinium 50 K and Affymetrix Axiom 600 K arrays). RESULTS: The effects of ascertainment bias of the 50 K and 600 K arrays were negligible for deciphering global genetic trends of diversity and for estimating relatedness in this panel. We developed an original approach based on linkage disequilibrium (LD) extent in order to determine whether SNPs significantly associated with a trait and that are physically linked should be considered as a single Quantitative Trait Locus (QTL) or several independent QTLs. Using this approach, we showed that the combination of the three technologies, which have different SNP distributions and densities, allowed us to detect more QTLs (gain in power) and potentially refine the localization of the causal polymorphisms (gain in resolution). CONCLUSIONS: Conceptually different technologies are complementary for detecting QTLs by tagging different haplotypes in association studies. Considering LD, marker density and the combination of different technologies (SNP-arrays and re-sequencing), the genotypic data available were most likely enough to well represent polymorphisms in the centromeric regions, whereas using more markers would be beneficial for telomeric regions.


Assuntos
Estudo de Associação Genômica Ampla/métodos , Técnicas de Genotipagem , Haplótipos , Análise de Sequência com Séries de Oligonucleotídeos , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Zea mays/genética , Alelos , Biodiversidade , Cromossomos de Plantas , Marcadores Genéticos , Genoma de Planta , Desequilíbrio de Ligação , Zea mays/crescimento & desenvolvimento
6.
Sci Total Environ ; 686: 819-827, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31195289

RESUMO

Despite the fact that it is the total crop production that shapes future food supply rather than one of its single component, previous studies have mainly focused on the changes in crop yield. It is possible that recent gains in crop production are mainly due to improvement of yield rather than growth of harvest area. However, it remains unclear about the geographical patterns of their relative contributions at fine scales and the possible mechanisms. Analysis of US maize production shows that maize production has increased significantly at a rate of 2.1%/year during 1980-2010. Although yield is the dominant factor contributing to production growth for the country as a whole, the importance of harvest area has become more evident with time. In 56% of US's maize growing counties, harvest area has also contributed more than yield to production changes. High spatial correlation between the change rates of harvest area and production is observed (R = 0.96), while a weak relation (R = 0.21) is found between the spatial patterns of yield and production. This suggests that harvest area has exerted the dominant role in modulating the spatial distribution pattern of maize production changes. Further analysis suggests that yield and harvest area respond differently to climate variability, which has great implications for adaptation strategies. Comparing 11 state-of-the-art crop model simulations against census data reveals large bias in the simulated spatial patterns of maize production. Nevertheless, such bias can be reduced substantially by incorporating the observed dynamics of harvest area, pointing to a potential pathway for future model improvement. This study highlights the importance of accounting for harvest area dynamics in assessing agricultural production empirically or with crop models.


Assuntos
Agricultura/métodos , Modelos Teóricos , Zea mays/crescimento & desenvolvimento , Agricultura/estatística & dados numéricos , Mudança Climática , Produção Agrícola , Produtos Agrícolas/crescimento & desenvolvimento , Abastecimento de Alimentos , Geografia , Estados Unidos
7.
J Agric Food Chem ; 67(25): 7050-7059, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31240932

RESUMO

This work aimed to investigate the effect of selenium (Se) and irrigation on the grain yield, on the forms of Se, phenols, and carotenes, and on some antioxidant activities of maize ( Zea mays L.) grains. To reach this goal, a 2 year experiment was undertaken. Maize was fertigated with sodium selenite at the rate of 200 g of Se ha-1 and grown under two water regimes. While the irrigation did not show a clear effect on the selected parameters, Se fertigation increased the contents of inorganic and organic Se forms, xanthophyll, and salicylic acid. Furthermore, while Se fertigation decreased the hydroxycinnamic acid content, generally higher antioxidant activities were found in Se-treated grains than in the control. These findings suggest that Se fertigation increases most of the nutraceutical values of maize grains, which therefore might improve human and livestock health and could increase the maize grain shelf life and its byproducts.


Assuntos
Antioxidantes/análise , Biofortificação/métodos , Suplementos Nutricionais/análise , Selenito de Sódio/metabolismo , Água/análise , Zea mays/química , Irrigação Agrícola , Antioxidantes/metabolismo , Alimentos Fortificados/análise , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Selenito de Sódio/análise , Solo/química , Água/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
8.
Syst Appl Microbiol ; 42(4): 517-525, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31176475

RESUMO

Plant roots are inhabited by a large diversity of microbes, some of which are beneficial for the growth of plants and known as plant growth promoting rhizobacteria (PGPR). In this work, we designed a multispecies inoculum of PGPRs containing Rhizobium phaseoli, Sinorhizobium americanum and Azospirillum brasilense nitrogen-fixing strains and other plant-growth promoting bacteria such as Bacillus amyloliquefaciens and Methylobacterium extorquens. We evaluated the effect of this group of bacteria on the growth of one-month-old maize plants. The multispecies inoculum exerted a beneficial effect on maize plants that was greater than that obtained with single-bacteria. Using the same multispecies inoculant, acetylene reduction was recorded in 5-day-old roots indicating active nitrogen fixation by bacteria in maize. Azospirillum nitrogen fixation was lower than that obtained with the multispecies inoculum. We focused on the analysis of R. phaseoli gene expression in presence of other PGPRs. Many R. phaseoli up- regulated genes in roots in the presence of other bacteria are hypothetical, showing our poor knowledge of bacteria-bacteria interactions. Other genes indicated bacterial nutrient competition and R. phaseoli stress. Differentially expressed transcriptional regulators were identified that may be key in bacteria-bacteria interaction regulation. Additionally, gene expression was analyzed from Azospirillum but not from sinorhizobia and methylobacteria due to the low number of transcripts obtained from maize roots. The metatranscriptomic analysis from maize roots showed expression of Azospirillum nif genes in the presence of PGPR bacteria. Our hypothesis is that other bacteria stimulate Azospirillum capacity to fix nitrogen and this should be further explored.


Assuntos
Bactérias/genética , Interações Microbianas , Fixação de Nitrogênio/genética , Reguladores de Crescimento de Planta/genética , Zea mays/microbiologia , Bactérias/metabolismo , Proteínas de Bactérias/genética , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Microbiota , Reguladores de Crescimento de Planta/metabolismo , Reguladores de Crescimento de Planta/fisiologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
9.
J Agric Food Chem ; 67(27): 7616-7625, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31251044

RESUMO

Rapid hydrolysis of urea results in further fertilization frequency and excessive nitrogen (N) input. A modified urea, dimethylolurea (DMU), was synthesized in this study. The structure of the sample was characterized by Fourier transform infrared and nuclear magnetic resonance analysis, manifesting the formation of DMU. N release investigation confirmed that DMU enabling provided a gradual N supply. The N leaching experiment indicated that increasing the applied DMU significantly reduced the NH4+-N, NO3--N, and total N leaching, compared with urea application alone. The application effect on maize and wheat was evaluated. The results revealed that singly applied DMU with 100% or 80% N input, irrespective of the amount, promoted crop yield and agronomic characteristic and N use efficiency (NUE) of maize and wheat, beyond urea with two split applications at the recommended rate. Thus, the potential availability of DMU was proven; this could be widely used in agricultural fields as a slow-release fertilizer.


Assuntos
Produtos Agrícolas/crescimento & desenvolvimento , Fertilizantes , Compostos de Metilureia/administração & dosagem , Nitrogênio/administração & dosagem , Agricultura/métodos , Preparações de Ação Retardada , Fertilizantes/análise , Compostos de Metilureia/síntese química , Compostos de Metilureia/química , Espectroscopia de Infravermelho com Transformada de Fourier , Triticum/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento
10.
Plant Cell Physiol ; 60(8): 1734-1746, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31076755

RESUMO

Pentatricopeptide repeat (PPR) proteins play crucial roles in intron splicing, which is important for RNA maturation. Identification of novel PPR protein with the function of intron splicing would help to understand the RNA splicing mechanism. In this study, we identified the maize empty pericarp602 (emp602) mutants, the mature kernels of which showed empty pericarp phenotype. We cloned the Emp602 gene from emp602 mutants and revealed that Emp602 encodes a mitochondrial-localized P-type PPR protein. We further revealed that Emp602 is specific for the cis-splicing of mitochondrial Nad4 intron 1 and intron 3, and mutation of Emp602 led to the loss of mature Nad4 transcripts. The loss of function of Emp602 nearly damaged the assembly and accumulation of complex I and arrested mitochondria formation, which arrested the seed development. The failed assembly of complex I triggers significant upregulation of Aox expression in emp602 mutants. Transcriptome analysis showed that the expression of mitochondrial-related genes, e.g. the genes associated with mitochondrial inner membrane presequence translocase complex and electron carrier activity, were extensively upregulated in emp602 mutant. These results demonstrate that EMP602 functions in the splicing of Nad4 intron 1 and intron 3, and the loss of function of Emp602 arrested maize seed development by disrupting the mitochondria complex I assembly.


Assuntos
Sementes/metabolismo , Zea mays/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Íntrons/genética , Íntrons/fisiologia , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , Processamento de RNA/genética , Processamento de RNA/fisiologia , Sementes/genética , Sementes/crescimento & desenvolvimento , Zea mays/genética , Zea mays/crescimento & desenvolvimento
11.
Int J Mol Sci ; 20(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31071964

RESUMO

The feasibility of thermography as a technique for plant screening aiming at drought-tolerance has been proven by its relationship with gas exchange, biomass, and yield. In this study, unlike most of the previous, thermography was applied for phenotyping contrasting maize genotypes whose classification for drought tolerance had already been established in the field. Our objective was to determine whether thermography-based classification would discriminate the maize genotypes in a similar way as the field selection in which just grain yield was taken into account as a criterion. We evaluated gas exchange, daily water consumption, leaf relative water content, aboveground biomass, and grain yield. Indeed, the screening of maize genotypes based on canopy temperature showed similar results to traditional methods. Nevertheless, canopy temperature only partially reflected gas exchange rates and daily water consumption in plants under drought. Part of the explanation may lie in the changes that drought had caused in plant leaves and canopy structure, altering absorption and dissipation of energy, photosynthesis, transpiration, and partitioning rates. Accordingly, although there was a negative relationship between grain yield and plant canopy temperature, it does not necessarily mean that plants whose canopies were maintained cooler under drought achieved the highest yield.


Assuntos
Secas , Estresse Fisiológico/genética , Termografia/métodos , Zea mays/metabolismo , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Genótipo , Fotossíntese/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Temperatura Ambiente , Água/metabolismo , Zea mays/genética , Zea mays/crescimento & desenvolvimento
12.
Environ Sci Pollut Res Int ; 26(19): 19261-19271, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31065988

RESUMO

Cadmium (Cd) contamination in agricultural soils is a prevalent environmental issue and poses potential threats to food security. Foliar ascorbic acid might prove a potent tool to alleviate toxicity of Cd toxicity in maize. An experiment was conducted with objectives to study exogenous ascorbic acid-modulated improvements in physiochemical attributes of maize under Cd toxicity. The experiment was conducted under completely randomized design. Treatments were comprised of varying concentrations of foliar ascorbic acid viz. 0.0, 0.1, 0.3, and 0.5 mM of AsA. Toxicity of Cd decreased the maize growth, increased lipid peroxidation, disturbed protein metabolism, and reduced the antioxidant defense capabilities compared with the control. However, foliar AsA significantly improved maize growth and development, photosynthetic capabilities, and protein concentrations in Cd-stressed maize plants. Meanwhile, the malondialdehyde contents and hydrogen peroxide accumulation levels in Cd-stressed maize plants decreased remarkably with increasing AsA concentrations. Furthermore, the combined treatments conspicuously boosted activities of superoxide dismutase, peroxidase, catalase, and glutathione reductase under the Cd stress alone. In addition, the application of AsA reduced the Cd uptake by 10.3-12.3% in grains. Conclusively, foliar ascorbic acid alleviated the negative effects of Cd stress in maize and improved photosynthetic processes, osmolytes, and antioxidant defense systems.


Assuntos
Antioxidantes/metabolismo , Ácido Ascórbico/farmacologia , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Zea mays/efeitos dos fármacos , Ácido Ascórbico/metabolismo , Cádmio/metabolismo , Relação Dose-Resposta a Droga , Peroxidação de Lipídeos/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Distribuição Aleatória , Poluentes do Solo/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo
13.
Environ Sci Pollut Res Int ; 26(20): 20689-20700, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31104234

RESUMO

Cadmium (Cd) toxicity in agricultural crops is a widespread problem. Little is known about biochar and arbuscular mycorrhizal fungi (AMF) effect on Cd concentration in maize plant either applied separately or in combination. Current study was performed to demonstrate effects of biochar and Rhizophagus clarus on plant growth, photosynthesis activity, nutrients (P, Ca, Mg, Fe, Cu, and Mn), and Cd concentration in maize grown in Cd-spiked soil. The alkaline soil was spiked by Cd factor at three levels: 0 (Cd 0), 5 (Cd 5), and 10 (Cd 10) mg/kg; biochar factor at two levels: 0 and 1%; and mycorrhizal inoculum factor at two levels: MF0 and MF1 (R. clraus). Plants were harvested after 70 days of seed germination, and various morphological and physiological parameters, as well as elemental concentration and root colonization, were recorded. Addition of biochar increased plant biomass by 21% (Cd 5) and 93% (Cd 10), MF1 enhanced by 53% (Cd 0) and 69% (Cd 10), while biochar + MF1 enhanced dry plant biomass by 70% (Cd 0) and 94% (Cd 10). Results showed maximum increase of 94% (Cd 10) in plant biomass was observed in Cd-spiked soil. Root colonization decreased proportionally by increasing Cd concentration and at Cd 10, colonization was 36.7% and 31.7% for MF1 and biochar + MF1 treatments, respectively. Besides that, addition of biochar enhanced root attributes (root length, volume, and surface area) by 34-58% compared to control in Cd 10. The MF1 increased these attributes by 11-78% while biochar + MF1 enhanced by 32-61% in Cd-spiked soil. However, biochar + MF1 neutralized Cd stress in maize plant for gaseous attributes (assimilation rate, transpiration rate, intercellular CO2, and stomatal conductance). The MF1 enhanced Cd concentration in plant as it was 3.32 mg/kg in Cd 5 and 6.73 mg/kg in Cd 10 treatments while addition of biochar phytostabilized Cd and reduced its concentration in plants by 2.0 mg/kg in Cd 5 and 4.27 mg/kg in Cd 10. The biochar + MF1 had 2.9 mg/kg and 4.8 mg/kg Cd concentration in Cd 5 and Cd 10 plants, respectively. Phosphorus concentration was augmented in shoots (up to 26%) and roots (up to 20%) of maize plant in biochar-amended soil than control plants. In biochar + MF1, concentration of P was 1.01% and 0.73% in Cd 5 and Cd 10, respectively. It is concluded that biochar + MF1 treatment enhances plant biomass while addition of sole biochar reduced Cd uptake, slightly indifferent to earlier treatment.


Assuntos
Cádmio/metabolismo , Carvão Vegetal/química , Glomeromycota/fisiologia , Micorrizas/fisiologia , Poluentes do Solo/metabolismo , Zea mays/crescimento & desenvolvimento , Biomassa , Cádmio/química , Cádmio/toxicidade , Carvão Vegetal/análise , Nutrientes/metabolismo , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Poluentes do Solo/química , Poluentes do Solo/toxicidade , Zea mays/metabolismo , Zea mays/microbiologia
14.
Exp Appl Acarol ; 77(4): 571-582, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31093857

RESUMO

The Banks grass mite, Oligonychus pratensis (Banks), and two-spotted spider mite, Tetranychus urticae Koch, are important chelicerae herbivores on irrigated corn in Kansas, USA. They cause loss of foliage, stalk breakage, kernel shrinkage and yield loss. Aerial application methods were evaluated to control spider mites in a commercial corn field in August, 2017, near Hoxie, Kansas. Dimethoate (0.56 kg active ingredient/ha) and Lorsban Advanced (1.05 kg active ingredient/ha) mixed with a nonionic surfactant, Traverse (0.25% v/v), were aerially applied using conventional flat-fan hydraulic nozzles at 28.1 L/ha and aerial electrostatic nozzles at 9.3 L/ha. To assess spray droplet spectra of the aerial application methods, water sensitive paper samplers were deployed at the whorl of husk leaves at the tip of the ear before aerial spray treatments were applied. Spray droplet spectra were quantified using commercial image analysis software. Treatment efficacy was assessed both objectively and subjectively. Objective efficacy evaluation incorporated the use of an active multispectral optical sensor via spectral analysis of the midrib regions of corn leaves on the abaxial surface where spider mites reside. Subjective damage ratings based upon in-field spider mite movement observations were scored by professional crop scouting consultants. Results of objective spectral analysis and subjective damage ratings indicated that both the conventional and electrostatic nozzles with 283 and 210-µm spray droplet 'volume median diameter' (VMD) at 28.1 and 9.3 L/ha, respectively, controlled spider mites compared to an untreated check.


Assuntos
Acaricidas , Clorpirifos , Dimetoato , Tetranychidae , Controle de Ácaros e Carrapatos , Animais , Kansas , Folhas de Planta , Controle de Ácaros e Carrapatos/métodos , Zea mays/crescimento & desenvolvimento
15.
J Plant Physiol ; 237: 111-119, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31071544

RESUMO

Plant growth-promoting rhizobacteria (PGPR) naturally aid plant growth, development and tolerance to stress. Yield increase by the commercial isolate Azospirillum lipoferum CRT1 was recently attributed to an enhanced sprouting success. In order to provide the first biochemical and physiological analysis of sprouting enhancement by PGPR, seed germination and metabolism were followed by time-lapse photography and GC/MS-based metabolomics, respectively, after inoculating two differentially-responding maize cultivars with A. lipoferum CRT1. Bacterial growth on the seeds and plantlet development were also determined. Bacterial inoculation of the seeds of one cultivar led to a 6-8 h hastening of radicle emergence, increased surface bacterial counts, lower contents of energetic primary metabolites before radicle emergence and increased photosynthetic yield, and root surface area, in 3-leaf plantlets. None of these changes were observed on the other maize cultivar that rather accumulated greater levels of stress-related metabolites shortly after radicle emergence. Bacterial counts and cell division-driven central root growth increased in parallel and similarly on both cultivars. A. lipoferum CRT1 stimulated pre-germinating or defense events in a cultivar-dependent manner in maize after rapid (less than 24 h) recognition with initially resting seeds. This PGPR isolate therefore bears agronomic potential as a biopriming agent.


Assuntos
Azospirillum lipoferum/fisiologia , Germinação , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia , Cromatografia Gasosa-Espectrometria de Massas , Metabolômica , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento
16.
J Agric Food Chem ; 67(20): 5736-5745, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31042035

RESUMO

As a potent herbicide capable of contaminating water and soil environments, paraquat, which is still widely used worldwide, is toxic to mammals, algae, aquatic animals, etc. Paraquat was loaded on novel nanoparticles composed of pectin, chitosan, and sodium tripolyphosphate (PEC/CS/TPP). The size, polydispersity index, and ζ potential of nanoparticles were characterized. Further assessments were carried out by SEM, AFM, FT-IR, and DSC. The encapsulation was highly efficient, and there was a delayed release pattern of paraquat. The encapsulated herbicide was less toxic to alveolar and mouth cell lines. Moreover, the mutagenicity of the formulation was significantly lower than those of pure or commercial forms of paraquat in a Salmonella typhimurium strain model. The soil sorption of paraquat and the deep soil penetration of the nanoparticle-associated herbicide were also decreased. The herbicidal activity of paraquat for maize or mustard was not only preserved but also enhanced after encapsulation. It was concluded that paraquat encapsulation with PEC/CS/TPP nanoparticles is highly efficient and the formulation has significant herbicide activity. It is less toxic to human environment and cells, as was evidenced by less soil sorption, cytotoxicity, and mutagenicity. Hence, paraquat-loaded PEC/CS/TPP nanoparticles have potential advantages for future use in agriculture.


Assuntos
Quitosana/química , Composição de Medicamentos/métodos , Herbicidas/química , Mutagênicos/química , Nanopartículas/química , Paraquat/química , Pectinas/química , Polifosfatos/química , Adsorção , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/química , Herbicidas/farmacologia , Herbicidas/toxicidade , Humanos , Cinética , Mostardeira/efeitos dos fármacos , Mostardeira/crescimento & desenvolvimento , Mutagênicos/farmacologia , Mutagênicos/toxicidade , Paraquat/farmacologia , Paraquat/toxicidade , Tamanho da Partícula , Solo/química , Poluentes do Solo/química , Poluentes do Solo/farmacologia , Poluentes do Solo/toxicidade , Zea mays/efeitos dos fármacos , Zea mays/crescimento & desenvolvimento
17.
Sci Total Environ ; 679: 328-336, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31100561

RESUMO

In order to feed a population of nearly 1.4 billion people with limited arable land resources, China's high crop production has been maintained by an intensive cropping system with excessive inputs of chemical fertilizers, resulting in high environmental costs. This study attempted to explore the reasonable balance between yield increase and nitrogen (N) inputs in the intensive wheat-maize cropping system in the North China Plain, which is one of the most important grain production regions in China. Based on yield simulations with the DSSAT-CERES-Wheat and DSSAT-CERES-Maize models and a household survey of 241 farmers' fields, we conducted a coupled analysis of the regional crop yields, N fertilizer inputs, and farmers' technical conversion efficiency with respect to winter wheat and summer maize production in four representative study areas. We also conducted a quantitative analysis of the equilibrium relationship between fertilizer application rates and expected yields, and the optimum N fertilization amounts for wheat and maize were recommended. The results indicated that farmers' average yields had reached almost 80% of the attainable yields, which meant that there was little room for farmers to increase their yields. However, we found that the yield gaps among the different farmers were still large, and most farmers applied excessive amounts of N while obtaining unsatisfactory yields due to poor fertilizer management techniques. Only 15% of winter wheat and 4% of summer maize on farmers' fields had achieved the synergy of high crop yields and efficient fertilization, and farmers' technical conversion efficiency was still relatively low. Therefore, farmers should be guided to appropriately lower their yield expectations and reduce the overuse of N fertilizer. In the future, if farmers receive necessary education and training and adopt advanced fertilizer management techniques, sustainable intensification of agricultural production with lower environmental costs will be feasible in China.


Assuntos
Agricultura/métodos , Fertilizantes/análise , Nitrogênio/análise , China , Produção Agrícola/métodos , Modelos Teóricos , Triticum/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento
18.
Mol Plant Microbe Interact ; 32(9): 1162-1174, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30933667

RESUMO

Soil microbial communities hold great potential for sustainable and ecologically compatible agriculture. Although numerous plant-beneficial bacterial strains from a wide range of taxonomic groups have been reported, very little evidence is available on the plant-beneficial role of bacteria from the genus Caulobacter. Here, the mode of action of a Caulobacter strain, designated RHG1, which had originally been identified through a microbial screen for plant growth-promoting (PGP) bacteria in maize (Zea mays), is investigated in Arabidopsis thaliana. RHG1 colonized both roots and shoots of Arabidopsis, promoted lateral root formation in the root, and increased leaf number and leaf size in the shoot. The genome of RHG1 was sequenced and was utilized to look for PGP factors. Our data revealed that the bacterial production of nitric oxide, auxins, cytokinins, or 1-aminocyclopropane-1-carboxylate deaminase as PGP factors could be excluded. However, the analysis of brassinosteroid mutants suggests that an unknown PGP mechanism is involved that impinges directly or indirectly on the pathway of this growth hormone.


Assuntos
Caulobacter , Interações Hospedeiro-Patógeno , Zea mays , Caulobacter/genética , Raízes de Plantas/microbiologia , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
19.
Ying Yong Sheng Tai Xue Bao ; 30(4): 1179-1187, 2019 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30994278

RESUMO

The application of large amounts of nitrogen (N) fertilizer can result in soil N accumulation and consequently N loss. To address these problems in a wheat-maize rotation area of the North China Plain, a two-year field experiment (2016-2017) was conducted to examine the effects of three different N fertilizer strategies on crop yield, N uptake, N loss and soil inorganic N content. The treatments were: controlled-release fertilizer, microbial fertilizer, nitrification inhibitor and farmer's practice (control). The results showed that the wheat yield from the microbial fertilizer treatment in 2016 was significantly lower than that from the controlled-release fertilizer treatment and the nitrification inhibitor treatment, but was not significantly different from conventional farmer fertilization. The N uptake of wheat and annual crops in the microbial fertilizer treatment was significantly reduced. There was no significant difference in crop yield and N uptake among the treatments in 2017. Soil fertility of the tillage layer was maintained or improved in all three treatments compared with the control, and the contents of alkali-hydrolyzed nitrogen, available potassium and organic matter increased with the increase of plant growth period in the microbial fertilizer treatment. Microbial fertilizer and nitrification inhibitor reduced the inorganic N content in the 40-100 cm soil profile, while controlled-release fertilizer increased the inorganic N content in the 0-40 cm soil layer. N loss through ammonia volatilization was higher than that through leaching, which was greater than the loss through N2O emission. Runoff loss was negligible. Among the treatments, N loss in farmer's practice treatment was the highest. Microbial fertilizer significantly reduced N loss through ammonia volatilization, but the loss through leaching was larger. In conclusion, with reduced N application compared with the farmer's practice, controlled release fertilizer and nitrification inhibitor could maintain crop yield and N uptake, and microbial fertilizer could ensure crop yield and N uptake for a longer plant growth period. The results suggested that inorganic N content in the 40-100 cm soil layer could be reduced in the soil by adding microbial fertilizer and nitrification inhibitors, and the amount of inorganic N was not reduced significantly by application of controlled release fertilizer. Several N reduction measures could reduce N loss. The microbial fertilizer treatment needed to be modified to reduce N leaching.


Assuntos
Agricultura/métodos , Fertilizantes , Nitrogênio , China , Fazendas , Rotação , Solo/química , Triticum/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento
20.
Ying Yong Sheng Tai Xue Bao ; 30(4): 1199-1206, 2019 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30994280

RESUMO

To improve water and nitrogen (N) fertilizer use efficiency, increase sustainable agricultural production, and explore the appropriate substitution level of inorganic N fertilizer by organic fertilizer in the semi-arid region of the western Loess Plateau, a three-year field experiment was conducted at the Dingxi Agri-ecological Station in 2016-2018. We examined the effects of commercial organic fertilizer substitution on maize grain yield as well as the use efficiency of water and N fertilizer under plastic film fully mulched ridge-furrow in dryland. There were six fertilizer treatments: T1, N fertilizer without organic fertilizer; T2, substitution 50% inorganic-N with organic-N; T3, substitution 37.5% inorganic-N with organic-N; T4, substitution 25% inorganic-N with organic-N; T5, substitution 12.5% inorganic-N with organic-N; and CK, no N fertilizer. The results showed that treatments of commercial organic fertilizer substitution (T2-T5) had higher grain yield and water and N efficiency than that in T1 treatment in dry year under 200 kg N·hm-2. The changes in grain yield and water and N fertilizer efficiency had no significant difference in treatments of commercial organic fertilizer substitution compared to T1 treatment in wet year. T2 and T3 treatments increased grain yield by 15.6% and 18.2%, and with 35.1% and 27.0% enhancement in harvest index compared to T1. T2 and T3 treatments increased water use efficiency, rainfall use efficiency, N agrono-mic efficiency and partial productivity of N fertilizer by 17.4% and 22.3%, 15.7% and 17.7%, 15.6% and 18.0%, 155.2% and 179.3%. These results demonstrated that under the same N input level, 50% and 37.5% substitution inorganic-N with organic-N could be a suitable substitution rate under plastic film fully mulched ridge-furrow, which could be recommended as a fertilizer application pattern in this area.


Assuntos
Agricultura/métodos , Fertilizantes , Nitrogênio/análise , Zea mays/crescimento & desenvolvimento , Plásticos , Solo , Água
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