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1.
Sci Rep ; 10(1): 1745, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-32019970

RESUMO

Fertilisation datasets collected from field experiments (n = 21) in tea-producing areas from 2016 to 2018 were used to build a quantitative evaluation of the fertility of tropical soils (QUEFTS) model to estimate nutrient uptake of tea plants, and to investigate relationships between tea yield and nutrient accumulation. The production of 1000 kg spring tea (based on one bud with two young expanding leaves) required 12.2 kg nitrogen (N), 1.2 kg phosphorus (P), and 3.9 kg potassium (K), and the corresponding internal efficiencies (IEs) for N, P, and K were 82.0, 833.3, and 256.4 kg kg-1. To produce 1000 kg summer tea, 9.1 kg N, 0.8 kg P, and 3.1 kg K were required, and the corresponding IEs for N, P, and K were 109.9, 1250.0, and 322.6 kg kg-1. For autumn tea, 8.8 kg N, 1.0 kg P, and 3.2 kg K were required to produce 1000 kg tea, and the corresponding IEs for N, P, and K were 113.6, 1000.0, and 312.5 kg kg-1. Field validation experiments performed in 2019 suggested that the QUEFTS model can appropriately estimate nutrient uptake of tea plants at a certain yield and contribute to developing a fertiliser recommendation strategy for tea production.

2.
Sci Total Environ ; : 135130, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31837865

RESUMO

Drainage and cultivation have turned peatlands from carbon (C) sinks into hotspots for greenhouse gas (GHG) emissions. Raising the water table and planting of winter cover crops are potential strategies to help reduce peat oxidation and re-initiate net C accumulation during the non-cropping period. However, the effects of these practices as well as their interactions on GHG emissions remain unclear. Here, we carried out an outdoor mesocosm experiment to elucidate the effect of water table levels (-30 cm and -50 cm) and winter cover crop cultivation (vetch, rye, no plant) on carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) fluxes during the winter period (November-April). Soil-atmosphere GHG exchange, GHG concentrations within the peat profile and soil water solute concentrations were monitored. Our results showed that high water table significantly reduced ecosystem respiration, while it had no net effect on N2O and CH4 fluxes. Uptake of available N by the cover crop significantly reduced nitrate in soil solution, thereby lowering the potential for leaching and both direct and indirect N2O emissions. No interactive effects between water table levels and cover crops were detected for any of the measured GHG fluxes. Seasonal variations of GHG fluxes were positively correlated with soil air concentrations at -15 cm and -40 cm depths, which were further regulated by dissolved organic C, nitrate concentration, and anaerobic conditions in the soil. This study suggests that there is great potential to raise water table levels and introduce green cover crops to reduce GHG emissions. Further studies are needed to achieve a complete evaluation of these strategies outside of the growing season, which may provide a significant mitigation benefit in C-rich cultivated peatlands.

3.
BMC Plant Biol ; 19(1): 108, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30894123

RESUMO

BACKGROUND: Nutrition with ammonium (NH4+) can enhance the drought tolerance of rice seedlings in comparison to nutrition with nitrate (NO3-). However, there are still no detailed studies investigating the response of nitric oxide (NO) to the different nitrogen nutrition and water regimes. To study the intrinsic mechanism underpinning this relationship, the time-dependent production of NO and its protective role in the antioxidant defense system of NH4+- or NO3--supplied rice seedlings were studied under water stress. RESULTS: An early NO burst was induced by 3 h of water stress in the roots of seedlings subjected to NH4+ treatment, but this phenomenon was not observed under NO3- treatment. Root oxidative damage induced by water stress was significantly higher for treatment with NO3- than with NH4+ due to reactive oxygen species (ROS) accumulation in the former. Inducing NO production by applying the NO donor 3 h after NO3- treatment alleviated the oxidative damage, while inhibiting the early NO burst by applying the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) increased root oxidative damage in NH4+ treatment. Application of the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester(L-NAME) completely suppressed NO synthesis in roots 3 h after NH4+ treatment and aggravated water stress-induced oxidative damage. Therefore, the aggravation of oxidative damage by L-NAME might have resulted from changes in the NOS-mediated early NO burst. Water stress also increased the activity of root antioxidant enzymes (catalase, superoxide dismutase, and ascorbate peroxidase). These were further induced by the NO donor but repressed by the NO scavenger and NOS inhibitor in NH4+-treated roots. CONCLUSION: These findings demonstrate that the NOS-mediated early NO burst plays an important role in alleviating oxidative damage induced by water stress by enhancing the antioxidant defenses in roots supplemented with NH4+.


Assuntos
Compostos de Amônio/farmacologia , Desidratação , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico/metabolismo , Oryza/fisiologia , Antioxidantes/metabolismo , Arginina/metabolismo , Citrulina/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Nitratos/metabolismo , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Nitroprussiato/farmacologia , Oryza/efeitos dos fármacos , Oxirredução , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo
4.
Physiol Plant ; 162(4): 467-478, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29080266

RESUMO

The effects of elevated CO2 (eCO2 ) on the relative uptake of inorganic and organic nitrogen (N) are unclear. The uptake of different N sources by pak choi (Brassica chinensis L.) seedlings supplied with a mixture of nitrate, glycine and ammonium was studied using 15 N-labelling under ambient CO2 (aCO2 ) (350 ppm) or eCO2 (650 ppm) conditions. 15 N-labelled short-term uptake and 15 N-gas chromatography mass spectrometry (GC-MS) were applied to measure the effects of eCO2 on glycine uptake and metabolism. Elevated CO2 increased the shoot biomass by 36% over 15 days, but had little effect on root growth. Over the same period, the N concentrations of shoots and roots were decreased by 30 and 2%, respectively. Elevated CO2 enhanced the uptake and N contribution of glycine, which accounted for 38-44% and 21-40% of total N uptake in roots and shoots, respectively, while the uptake of nitrate and ammonium was reduced. The increased glycine uptake resulted from the enhanced active uptake and enhanced metabolism in the roots. We conclude that eCO2 may increase the uptake and contribution of organic N forms to total plant N nutrition. Our findings provide new insights into plant N regulation under eCO2 conditions.


Assuntos
Brassica/metabolismo , Dióxido de Carbono/metabolismo , Compostos de Amônio/metabolismo , Biomassa , Glicina/metabolismo , Nitratos/metabolismo , Nitrogênio/metabolismo , Brotos de Planta/metabolismo
5.
BMC Plant Biol ; 17(1): 58, 2017 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-28253854

RESUMO

BACKGROUND: Plants can absorb amino acids as a nitrogen (N) source, and glucose is an important part of root rhizodeposition and the soil sugar pool, which participates in the regulation of plant growth and uptake. In pakchoi, the effect of glucose concentration on the glycine N uptake from a nutrient mixture composed of glycine, ammonium, and nitrate, or from a single N solution of glycine alone was studied using specific substrate 15N-labeling and 15N-gas chromatography mass spectrometry. RESULTS: The optimal glucose concentration for plant growth was 4.5 µM or 25 µM when supplied with glycine alone or the N mixture, respectively, and resulted in a >25% increase in seedling biomass. The addition of glucose affected the relative contribution from organic or inorganic sources to overall N uptake. When glucose was added at optimal concentrations, glycine was preferentially used as an N source, while the relative contribution from nitrate was reduced. The limiting step for glycine N contribution was active uptake in the roots in high glucose and single-N-source conditions; however, root metabolism of glycine to serine was limiting in high-glucose and mixed-N-source conditions. CONCLUSIONS: The addition of low concentrations of glucose increased the relative uptake of organic nitrogen and reduced the uptake of nitrate, suggesting a feasible way to decrease nitrate content and increase the edible quality of vegetables.


Assuntos
Brassica/metabolismo , Glucose/metabolismo , Glicina/metabolismo , Nitrogênio/metabolismo , Aminoácidos/metabolismo , Biomassa , Brassica/efeitos dos fármacos , Brassica/crescimento & desenvolvimento , Enzimas/metabolismo , Glucose/farmacologia , Glicina/farmacocinética , Hidroponia , Isótopos de Nitrogênio , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo
6.
Ecotoxicol Environ Saf ; 139: 384-393, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28189780

RESUMO

Chromium (Cr) pollution affects plant growth and biochemical processes, so, the relative uptake of glycine, nitrate, and ammonium by pak choi (Brassica chinensis) seedlings in treatments with 0mgL-1 and 10mgL-1 Cr (VI) were detected by substrate-specific 15N-labelling in a sterile environment. The short-term uptake of 15N-labelled sources and 15N-enriched amino acids were detected by gas chromatography mass spectrometry to explore the mechanism by which Cr stress affects glycine uptake and metabolism, which showing that Cr stress hindered the uptake of ammonium and glycine but increased significantly the uptake of nitrate. Cr stress did not decrease the active or passive uptake of glycine, but it inhibited the conversion of glycine to serine in pak choi roots, indicating that the metabolism of glycine to serine in roots, rather than the root uptake, was the limiting step in glycine contribution to total N uptake in pak choi. Since Cr affects the relative uptake of different N sources, a feasible way to reduce Cr-induced stress is application of selective fertilization, in particular nitrate, in pak choi cultivation on Cr-polluted soil.


Assuntos
Compostos de Amônio/metabolismo , Brassica/metabolismo , Cromo/farmacologia , Glicina/metabolismo , Nitratos/metabolismo , Aminoácidos/metabolismo , Cromo/metabolismo , Raízes de Plantas/metabolismo , Poluentes do Solo/farmacologia
7.
PLoS One ; 11(6): e0157979, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27337100

RESUMO

Amino acids are important sources of soil organic nitrogen (N), which is essential for plant nutrition, but detailed information about which amino acids predominant and whether amino acid composition varies with elevation is lacking. In this study, we hypothesized that the concentrations of amino acids in soil would increase and their composition would vary along the elevational gradient of Taibai Mountain, as plant-derived organic matter accumulated and N mineralization and microbial immobilization of amino acids slowed with reduced soil temperature. Results showed that the concentrations of soil extractable total N, extractable organic N and amino acids significantly increased with elevation due to the accumulation of soil organic matter and the greater N content. Soil extractable organic N concentration was significantly greater than that of the extractable inorganic N (NO3--N + NH4+-N). On average, soil adsorbed amino acid concentration was approximately 5-fold greater than that of the free amino acids, which indicates that adsorbed amino acids extracted with the strong salt solution likely represent a potential source for the replenishment of free amino acids. We found no appreciable evidence to suggest that amino acids with simple molecular structure were dominant at low elevations, whereas amino acids with high molecular weight and complex aromatic structure dominated the high elevations. Across the elevational gradient, the amino acid pool was dominated by alanine, aspartic acid, glycine, glutamic acid, histidine, serine and threonine. These seven amino acids accounted for approximately 68.9% of the total hydrolyzable amino acid pool. The proportions of isoleucine, tyrosine and methionine varied with elevation, while soil major amino acid composition (including alanine, arginine, aspartic acid, glycine, histidine, leucine, phenylalanine, serine, threonine and valine) did not vary appreciably with elevation (p>0.10). The compositional similarity of many amino acids across the elevational gradient suggests that soil amino acids likely originate from a common source or through similar biochemical processes.


Assuntos
Aminoácidos/análise , Meio Ambiente , Nitrogênio/análise , Solo/química , China , Ecossistema , Hidrólise
8.
Sci Rep ; 6: 21200, 2016 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-26882864

RESUMO

The uptake of glycine by pakchoi (Brassica chinensis L.), when supplied as single N-source or in a mixture of glycine and inorganic N, was studied at different light intensities under sterile conditions. At the optimal intensity (414 µmol m(-2) s(-1)) for plant growth, glycine, nitrate, and ammonium contributed 29.4%, 39.5%, and 31.1% shoot N, respectively, and light intensity altered the preferential absorption of N sources. The lower (15)N-nitrate in root but higher in shoot and the higher (15)N-glycine in root but lower in shoot suggested that most (15)N-nitrate uptake by root transported to shoot rapidly, with the shoot being important for nitrate assimilation, and the N contribution of glycine was limited by post-uptake metabolism. The amount of glycine that was taken up by the plant was likely limited by root uptake at low light intensities and by the metabolism of ammonium produced by glycine at high light intensities. These results indicate that pakchoi has the ability to uptake a large quantity of glycine, but that uptake is strongly regulated by light intensity, with metabolism in the root inhibiting its N contribution.


Assuntos
Brassica/metabolismo , Brassica/efeitos da radiação , Glicina/metabolismo , Luz , Aminoácidos/metabolismo , Compostos de Amônio/metabolismo , Biomassa , Nitratos/metabolismo , Nitrogênio/metabolismo , Fotossíntese , Raízes de Plantas/metabolismo
9.
Ying Yong Sheng Tai Xue Bao ; 26(3): 919-29, 2015 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-26211077

RESUMO

Plant can directly take up the intact amino acids, thus bypass the microbial mineralization of organic nitrogen. As an excellent carbon and nitrogen source, there exists competition for amino acid absorption between plant roots.and soil microorganisms. And the total flux of amino acids in soil may be enormous due to the extensive sources and short half-life. Studies on amino acid nitrogen nutritional contribution for plant by the technique of nitrogen isotopic tracer, has become a research topic in recent years ,which will help us better understand the principle of soil fertility. This paper summarized the recent researches on amino acid morphological characteristics in soil and its metabolic mechanism and nitrogen nutritional contribution for plant in different ecosystems, and discussed the present status and development trend of the amino acid circulation mechanism in the plant-soil-microorganism ecosystem and its bioavailability for plant. Finally, the topics of environmental regulating mechanism of amino acid bioavailability, amino acid carbon-nitrogen metabolism, and how to improve the field organic nitrogen management were all the core issues to be resolved.


Assuntos
Aminoácidos/metabolismo , Plantas/metabolismo , Solo/química , Carbono/metabolismo , Ecossistema , Nitrogênio/metabolismo , Isótopos de Nitrogênio , Raízes de Plantas , Microbiologia do Solo
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