Nitrogen

Barker, Allen V.; Bryson, Gretchen M.

doi:10.1201/9781420014877.sec2

Cited by 25 publications

(17 citation statements)

References 130 publications

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“…Moreover, plants cultivated in the tropical soils of low pH favour the uptake of N from ammonium or amino acid sources [ 49 ]. These N sources can influence the plant-N content since plants grown under ammonium-N condition will have twice the amount of N in their vegetative parts compared to those grown under nitrate-N condition [ 50 ].…”

Section: Discussionmentioning

confidence: 99%

“…40%. The present plant stalks which contained between 30.5–31.3% of total plant top N could possibly have several times higher nitrate concentration than the N in the leaves [ 50 ] and the nitrate-N is readily available for N remobilisation [ 54 ]. In general, the present study has demonstrated that leaves (old, ear and young), tassel and stalk of maize plants had served successively as N sinks and N sources towards ear formation.…”

Section: Discussionmentioning

confidence: 99%

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Plant Growth-Promoting Rhizobacteria Inoculation to Enhance Vegetative Growth, Nitrogen Fixation and Nitrogen Remobilisation of Maize under Greenhouse Conditions

et al. 2016

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Plant growth-promoting rhizobacteria (PGPR) may provide a biological alternative to fix atmospheric N2 and delay N remobilisation in maize plant to increase crop yield, based on an understanding that plant-N remobilisation is directly correlated to its plant senescence. Thus, four PGPR strains were selected from a series of bacterial strains isolated from maize roots at two locations in Malaysia. The PGPR strains were screened in vitro for their biochemical plant growth-promoting (PGP) abilities and plant growth promotion assays. These strains were identified as Klebsiella sp. Br1, Klebsiella pneumoniae Fr1, Bacillus pumilus S1r1 and Acinetobacter sp. S3r2 and a reference strain used was Bacillus subtilis UPMB10. All the PGPR strains were tested positive for N2 fixation, phosphate solubilisation and auxin production by in vitro tests. In a greenhouse experiment with reduced fertiliser-N input (a third of recommended fertiliser-N rate), the N2 fixation abilities of PGPR in association with maize were determined by 15N isotope dilution technique at two harvests, namely, prior to anthesis (D50) and ear harvest (D65). The results indicated that dry biomass of top, root and ear, total N content and bacterial colonisations in non-rhizosphere, rhizosphere and endosphere of maize roots were influenced by PGPR inoculation. In particular, the plants inoculated with B. pumilus S1r1 generally outperformed those with the other treatments. They produced the highest N2 fixing capacity of 30.5% (262 mg N2 fixed plant−1) and 25.5% (304 mg N2 fixed plant−1) of the total N requirement of maize top at D50 and D65, respectively. N remobilisation and plant senescence in maize were delayed by PGPR inoculation, which is an indicative of greater grain production. This is indicated by significant interactions between PGPR strains and time of harvests for parameters on N uptake and at. % 15Ne of tassel. The phenomenon is also supported by the lower N content in tassels of maize treated with PGPR, namely, B. pumilus S1r1, K. pneumoniae Fr1, B. subtilis UPMB10 and Acinetobacter sp. S3r2 at D65 harvest. This study provides evidence that PGPR inoculation, namely, B. pumilus S1r1 can biologically fix atmospheric N2 and provide an alternative technique, besides plant breeding, to delay N remobilisation in maize plant for higher ear yield (up to 30.9%) with reduced fertiliser-N input.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Plant Growth-Promoting Rhizobacteria Inoculation to Enhance Vegetative Growth, Nitrogen Fixation and Nitrogen Remobilisation of Maize under Greenhouse Conditions

et al. 2016

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“…Generally, in legumes, nodulation and nif-gene abundance decline at high levels of available soil N due to high C investments of plants to nodules and the N 2 -fixation process, 46 which only pays off under N-limiting conditions. Typically, sandy soils are more prone to NO 3 – leaching than clay soils, 47 and nitrification was repeatedly shown to be inhibited under acidic conditions. 48 , 49 Therefore, our data suggest a lower NO 3 – availability in the acidic sand control soil, resulting in a low NR activity that was overcompensated by high nodule biomass and high symbiotic N 2 fixation (percent NdfA) (Figures 1 C and 3 B).…”

Section: Discussionmentioning

confidence: 99%

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans

Oburger

Cid

Preiner

et al. 2018

Environ. Sci. Technol.

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Increasing use of tungsten (W)-based products opened new pathways for W into environmental systems. Due to its chemical alikeness with molybdenum (Mo), W is expected to behave similarly to its “twin element”, Mo; however, our knowledge of the behavior of W in the plant–soil environment remains inadequate. The aim of this study was to investigate plant growth as well as W and nutrient uptake depending on soil chemical properties such as soil pH and texture. Soybean (Glycine max cv. Primus) was grown on two acidic soils differing in soil texture that were either kept at their natural soil pH (pH of 4.5–5) or limed (pH of ≥7) and amended with increasing concentrations of metallic W (control and 500 and 5000 mg kg–1). In addition, the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N2 fixation (nitrogenase) was also investigated. Our results showed that the risk of W entering the food web was significantly greater in high-pH soils due to increased solubility of mainly monomeric W. The effect of soil texture on W solubility and phytoavailability was less pronounced compared to soil pH. Particularly at intermediate W additions (W 500 mg kg–1), symbiotic nitrogen fixation was able to compensate for reduced leaf nitrate reductase activity. When W soil solution concentrations became too toxic (W 5000 mg kg–1), nodulation was more strongly inhibited than nitrogenase activity in the few nodules formed, suggesting a more-efficient detoxification and compartmentalization mechanism in nodules than in soybean leaves. The increasing presence of polymeric W species observed in low-pH soils spiked with high W concentrations resulted in decreased W uptake. Simultaneously, polymeric W species had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our study demonstrates the importance of accounting for soil pH in risk assessment studies of W in the plant–soil environment, something that has been completely neglected in the past.

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“…Under field conditions, nitrogen nutrition is one of the major factors that influence plant growth [ 1 , 2 ]. The availability of this nutrient affects many processes of the plant, among which development, architecture, flowering, senescence, photosynthesis and photosynthates allocation [ 1 - 7 ].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of protein pattern changes in roots and leaves of Zea maysplants in response to nitrate availability by two-dimensional gel electrophoresis analysis

et al. 2009

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BackgroundNitrogen nutrition is one of the major factors that limit growth and production of crop plants. It affects many processes, such as development, architecture, flowering, senescence and photosynthesis. Although the improvement in technologies for protein study and the widening of gene sequences have made possible the study of the plant proteomes, only limited information on proteome changes occurring in response to nitrogen amount are available up to now. In this work, two-dimensional gel electrophoresis (2-DE) has been used to investigate the protein changes induced by NO3- concentration in both roots and leaves of maize (Zea mays L.) plants. Moreover, in order to better evaluate the proteomic results, some biochemical and physiological parameters were measured.ResultsThrough 2-DE analysis, 20 and 18 spots that significantly changed their amount at least two folds in response to nitrate addition to the growth medium of starved maize plants were found in roots and leaves, respectively. Most of these spots were identified by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS). In roots, many of these changes were referred to enzymes involved in nitrate assimilation and in metabolic pathways implicated in the balance of the energy and redox status of the cell, among which the pentose phosphate pathway. In leaves, most of the characterized proteins were related to regulation of photosynthesis. Moreover, the up-accumulation of lipoxygenase 10 indicated that the leaf response to a high availability of nitrate may also involve a modification in lipid metabolism.Finally, this proteomic approach suggested that the nutritional status of the plant may affect two different post-translational modifications of phosphoenolpyruvate carboxylase (PEPCase) consisting in monoubiquitination and phosphorylation in roots and leaves, respectively.ConclusionThis work provides a first characterization of the proteome changes that occur in response to nitrate availability in leaves and roots of maize plants. According to previous studies, the work confirms the relationship between nitrogen and carbon metabolisms and it rises some intriguing questions, concerning the possible role of NO and lipoxygenase 10 in roots and leaves, respectively. Although further studies will be necessary, this proteomic analysis underlines the central role of post-translational events in modulating pivotal enzymes, such as PEPCase.

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Nitrogen

Cited by 25 publications

References 130 publications

Plant Growth-Promoting Rhizobacteria Inoculation to Enhance Vegetative Growth, Nitrogen Fixation and Nitrogen Remobilisation of Maize under Greenhouse Conditions

Plant Growth-Promoting Rhizobacteria Inoculation to Enhance Vegetative Growth, Nitrogen Fixation and Nitrogen Remobilisation of Maize under Greenhouse Conditions

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans

Evaluation of protein pattern changes in roots and leaves of Zea maysplants in response to nitrate availability by two-dimensional gel electrophoresis analysis

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