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Nitrogen, Volume 4, Issue 2 (June 2023) – 6 articles

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14 pages, 667 KiB  
Article
Ammonium Fertilization Enhances Nutrient Uptake, Specifically Manganese and Zinc, and Growth of Maize in Unlimed and Limed Acidic Sandy Soil
by Asif Naeem, Philipp Deppermann and Karl H. Mühling
Nitrogen 2023, 4(2), 239-252; https://doi.org/10.3390/nitrogen4020017 - 19 Jun 2023
Cited by 3 | Viewed by 1876
Abstract
Although NH4+ fertilization is known to acidify rhizosphere and enhance nutrient uptake, the effects on a nutrient-sufficient acidic soil amended with lime are not demonstrated. Thus, the influence of NH4+ fertilization of an unlimed and limed (3 g calcium [...] Read more.
Although NH4+ fertilization is known to acidify rhizosphere and enhance nutrient uptake, the effects on a nutrient-sufficient acidic soil amended with lime are not demonstrated. Thus, the influence of NH4+ fertilization of an unlimed and limed (3 g calcium carbonate per kg soil) acidic soil on the nutrient uptake and growth of maize was studied in comparison to NH4NO3 fertilization. The pH of limed rhizosphere soil was about two units higher than that of the unlimed soil. The maize plants were grown in pots under greenhouse conditions for about two months. The results showed that the pH of the NH4+-fertilized unlimed and limed soil was 0.54 and 0.15 units lower than the NH4NO3-fertilized soil. Liming negatively affected shoot and root dry matter production, whereas the NH4+-fertilized plants produced higher dry matter than the NH4NO3-fertilized plants, with significant difference of 28% in the limed soil only. Liming decreased Fe concentration in rhizosphere soil from 99 to 69 mg kg−1 and decreased plant-available Mn the most (71%), whereas the NH4+-fertilized unlimed and limed soil had 48% and 21% higher Mn concentration than the respective NH4NO3-fertilized soils. Similarly limed rhizosphere soil had 50% lower plant-available Zn concentration than the unlimed soil, and the NH4+-fertilized soil had an 8% higher Zn concentration than the NH4NO3-fertilized unlimed soil. The liming negatively affected P, K, Mn, and Zn concentrations and contents in maize shoot to a lower degree in the NH4+-fertilized soil, whereas the positive effect of NH4+ on the nutrient concentration and contents was vigorous in the unlimed soil than the limed soil. It is concluded that NH4+ fertilization could be beneficial in enhancing nutrient uptake and growth of maize in both acidic and alkaline soils, despite the higher inherent plant-available concentrations of the nutrient in soil. Full article
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8 pages, 1012 KiB  
Communication
Isoenzymatic Pattern of Hydrogen Sulfide (H2S)-Generating L-Cysteine Desulfhydrase (LCD) in Arabidopsis thaliana Seedlings: Effect of Nitric Oxide (NO) and H2S
by Jorge De La O-Sánchez, María A. Muñoz-Vargas, José M. Palma and Francisco J. Corpas
Nitrogen 2023, 4(2), 231-238; https://doi.org/10.3390/nitrogen4020016 - 2 Jun 2023
Viewed by 1333
Abstract
In higher plants, hydrogen sulfide (H2S) is a recognized signaling molecule that performs multiple regulatory functions. The enzyme L-cysteine desulfhydrase (LCD) catalyzes the conversion of L-cysteine (L-Cys) to pyruvate and ammonium with the concomitant generation of H₂S, and it is considered [...] Read more.
In higher plants, hydrogen sulfide (H2S) is a recognized signaling molecule that performs multiple regulatory functions. The enzyme L-cysteine desulfhydrase (LCD) catalyzes the conversion of L-cysteine (L-Cys) to pyruvate and ammonium with the concomitant generation of H₂S, and it is considered one of the main sources of H2S in plants. Using non-denaturing polyacrylamide gel electrophoresis (PAGE) in combination with a specific assay for LCD activity, this study aims to identify the potential LCD isozymes in wild-type Arabidopsis thaliana seedlings of 16 days old grown under in vitro conditions, and to evaluate the potential impact of nitric oxide (NO) and H2S on these LCD isozymes. For this purpose, an Atnoa1 mutant characterized to have a low endogenous NO content as well as the exogenous application of H2S were used. Five LCD isozymes were detected, with LCD IV being the isozyme that has the highest activity. However, the LCD V activity was the only one that was positively modulated in the Atnoa1 mutants and by exogenous H2S. To our knowledge, this is the first report showing the different LCD isozymes present in Arabidopsis seedlings and how their activity is affected by NO and H2S content. Full article
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8 pages, 1589 KiB  
Communication
“Alperujo” Compost Improves Nodulation and Symbiotic Nitrogen Fixation of Soybean Inoculated with Bradyrhizobium diazoefficiens
by Germán Tortosa, Socorro Mesa, María J. Delgado and Carol V. Amaya-Gómez
Nitrogen 2023, 4(2), 223-230; https://doi.org/10.3390/nitrogen4020015 - 16 May 2023
Cited by 3 | Viewed by 2043
Abstract
The utilization of compost to enhance plant productivity and symbiotic nitrogen fixation (SNF) has been recognized as an effective alternative to synthetic nitrogen fertilizers. This environmentally sustainable method is readily accessible to farmers. This study investigated the effect of olive pomace (“alperujo”, AL) [...] Read more.
The utilization of compost to enhance plant productivity and symbiotic nitrogen fixation (SNF) has been recognized as an effective alternative to synthetic nitrogen fertilizers. This environmentally sustainable method is readily accessible to farmers. This study investigated the effect of olive pomace (“alperujo”, AL) compost on the nodulation and SNF of soybeans (Glycine max L.) and their natural symbiont (Bradyrhizobium diazoefficiens). For that, soybean plants were subjected to several doses of AL compost under controlled greenhouse conditions. At the end of the experiment, the dry weight of plant biomass (aerial part and roots), the number and fresh weight of nodules, and nitrogen and leghaemoglobin contents were analyzed. The application of AL compost significantly improved soybean growth, as demonstrated by an increase in both plant biomass and height. Furthermore, nodular leghaemoglobin content and nitrogen content were found to be enhanced by the addition of AL compost (7 and 40%, respectively), indicating an increase in nodule effectiveness and symbiotic efficiency. Our results provide clear evidence of the synergetic effect of AL compost on the soybean-B. diazoefficiens association, probably due to AL-compost improved soybean roots development, and rhizospheric organic matter and nutrients assimilation by rhizobia. Full article
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14 pages, 2807 KiB  
Article
Nitrogen Metabolism in Non-Nodulated and Nodulated Soybean Plants Related to Ureide Synthesis
by Takuji Ohyama, Kahori Matsumoto, Haruka Goto, Akihiro Saito and Kyoko Higuchi
Nitrogen 2023, 4(2), 209-222; https://doi.org/10.3390/nitrogen4020014 - 7 May 2023
Cited by 2 | Viewed by 2107
Abstract
Soybean plants can fix atmospheric N2 in the root nodule, a symbiotic organ with rhizobia. The primary forms of N transported from N2 fixation are ureides, allantoate, and allantoin, supplemented with asparagine. The nitrate absorbed in the roots is transported to [...] Read more.
Soybean plants can fix atmospheric N2 in the root nodule, a symbiotic organ with rhizobia. The primary forms of N transported from N2 fixation are ureides, allantoate, and allantoin, supplemented with asparagine. The nitrate absorbed in the roots is transported to the shoots in the forms of NO3 and asparagine with a little portion of ureides. The concentrations of N-metabolites were analyzed by capillary electrophoresis after supplying various concentrations of urea, precursors of ureides, and allopurinol, an inhibitor of xanthine dehydrogenase, to investigate the ureide synthesis pathway in the roots. When the non-nodulated soybean plants were treated with 0–5 mM of urea, the concentrations of asparagine and glutamine in the xylem sap and the roots increased remarkably. In addition, allantoate concentration increased with the urea concentrations becoming higher. Allopurinol inhibited the accumulation of allantoate but did not affect the asparagine and glutamine accumulation in roots, stems, leaves, and xylem sap, supporting that allantoate is synthesized by purine degradation in roots the same as in the nodules. When ureide precursors were supplied to the nodulated soybean plants, the concentrations of asparagine and glutamine in the xylem sap and roots increased, suggesting that the ureide precursors were absorbed and assimilated to amides in the roots. Full article
(This article belongs to the Special Issue Nitrogen Metabolism: From Plant Cell to Field and Vice Versa)
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15 pages, 1931 KiB  
Article
The Influence of Nitrogen Applications and Low Rainfall Conditions on Yield of Mixed Grass-Legume Grassland for 2 Years
by Karin Weggler and Martin Elsäßer
Nitrogen 2023, 4(2), 194-208; https://doi.org/10.3390/nitrogen4020013 - 28 Apr 2023
Viewed by 1469
Abstract
Mixed-species grassland containing legumes were suggested to increase yield compared to monocultures. Furthermore, some legumes were suggested to be able to sustain growth, even under drought conditions. The first aim of the current study was to measure if multispecies grassland with legumes is [...] Read more.
Mixed-species grassland containing legumes were suggested to increase yield compared to monocultures. Furthermore, some legumes were suggested to be able to sustain growth, even under drought conditions. The first aim of the current study was to measure if multispecies grassland with legumes is also more productive when their N input due to symbiotic N2 fixation is taken into account. Our second aim was to determine the benefit of grass–legume mixtures in terms of dry matter production under naturally occurring drought conditions. Mixed-species grasslands, consisting of monocultures and variable mixtures of (a) Trifolium pratense, (b) Trifolium. repens, (c) Lolium perenne, and (d) a mixture of drought-tolerant grasses (GSWT based), were assessed for their dry matter production over two years with contrasting weather patterns. The legume–grass seeding mixtures received either a fixed (180 kg N ha−1) or adapted N-fertilizer application (0–180 kg N ha−1), with the latter taking the assumed symbiotic N2 fixation by legumes into account. Mixed-species grassland showed improved yield compared to monocultures both in comparably humid and drought-affected years. The benefits of multispecies grass–legume mixtures were considerably more obvious under a fixed but still measurable under an adapted N-fertilizer regime. The species diversity effect appears to be significantly dependent on the additional N supply enabled by legumes’ symbiotic N2-fixation. Legumes and drought-tolerant grasses yielded equally well under drought conditions, although legumes showed major advantages during moderate drought and humid conditions. White and red clover, although both legumes, differed significantly in their persistence under elevated-N and their dry matter production under low-N fertilizer application, but were equal in their tolerance towards drought. Full article
(This article belongs to the Special Issue Optimizing Fertilizer Nitrogen Use on Crops)
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25 pages, 3163 KiB  
Article
Biodiversity-Based Empirical Critical Loads of Nitrogen Deposition in the Athabasca Oil Sands Region
by Nicole Vandinther and Julian Aherne
Nitrogen 2023, 4(2), 169-193; https://doi.org/10.3390/nitrogen4020012 - 13 Apr 2023
Viewed by 1403
Abstract
Anthropogenic nitrogen (N) emissions can have considerable effects on terrestrial ecosystems, with chronic N deposition leading to changes in plant species composition. The Athabasca Oil Sands Region (AOSR) represents a large point source of N emissions, which has prompted concern for surrounding habitats. [...] Read more.
Anthropogenic nitrogen (N) emissions can have considerable effects on terrestrial ecosystems, with chronic N deposition leading to changes in plant species composition. The Athabasca Oil Sands Region (AOSR) represents a large point source of N emissions, which has prompted concern for surrounding habitats. The objective of this study was to determine the relative importance of N deposition as a driver of plant species community composition against bioclimatic and soil chemical variables. Further, we sought to identify community thresholds in plant species composition across a N deposition gradient. This assessment was performed for 46 Jack pine (Pinus banksiana Lamb.)-dominant forest sites surrounding the AOSR spanning Alberta and Saskatchewan. In total, 35 environmental variables were evaluated using redundancy analysis (RDA), followed by gradient forest analysis applied to plant species abundance data. Soil chemical variables accounted for just over 26% of the total explainable variation in the dataset, followed by bioclimatic variables (19%) and deposition variables (5%), but joint effects between variables also explained a significant portion of the total variation (p < 0.001). Total deposited nitrogen (TDN), and sulphur (TDS) along with bioclimatic and soil chemical variables, were identified as important variables in gradient forest analysis. A single, definitive threshold across TDN was identified at approximately 5.6 kg N ha−1 yr−1 (while a TDS threshold was found at 14.4 kg S ha−1 yr−1). The TDN threshold range was associated primarily with changepoints for several vascular species (Pyrola asarifolia, Pyrola chlorantha, Cornus canadensis, and Arctostaphylos uva-ursi) and bryophyte and lichen species (Pleurozium schreberi, Vulpicida pinastri, and Dicranum polysetum). These results suggest that across Jack pine-dominant forests surrounding the AOSR, the biodiversity-based empirical critical load of nutrient N is 5.6 kg N ha−1 yr−1. Full article
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