Effects of nitrogen source and ectomycorrhizal association on growth and δ15N of two subtropical Eucalyptus species from contrasting ecosystems

2006 ◽  
Vol 33 (4) ◽  
pp. 367 ◽  
Author(s):  
Susanne Schmidt ◽  
Linda L. Handley ◽  
Tanuwong Sangtiean

Ectomycorrhizal (EM) associations facilitate plant nitrogen (N) acquisition, but the contribution of EM associations to tree N nutrition is difficult to ascertain in ecosystems. We studied the abilities of subtropical EM fungi and nutritionally contrasting Eucalyptus species, Eucalyptus grandis W.Hill ex Maiden and Eucalyptus racemosa Cav, to use N sources in axenic and soil cultures, and determined the effect of EM fungi on plant N use and plant 15N natural abundance (δ15N). As measured by seedling growth, both species showed little dependence on EM when growing in the N-rich minerotrophic soil from E. grandis rainforest habitat or in axenic culture with inorganic N sources. Both species were heavily dependent on EM associations when growing in the N-poor, organotrophic soil from the E. racemosa wallum habitat or in axenic culture with organic N sources. In axenic culture, EM associations enabled both species to use organic N when supplied with amide-, peptide- or protein-N. Grown axenically with glutamine- or protein-N, δ15N of almost all seedlings was lower than source N. The δ15N of all studied organisms was higher than the N source when grown on glutathione. This unexpected 15N enrichment was perhaps due to preferential uptake of an N moiety more 15N-enriched than the bulk molecular average. Grown with ammonium-N, the δ15N of non-EM seedlings was mostly higher than that of source N. In contrast, the δ15N of EM seedlings was mostly lower than that of source N, except at the lowest ammonium concentration. Discrimination against 15N was strongest when external ammonium concentration was high. We suggest that ammonium assimilation via EM fungi may be the cause of the often observed distinct foliar δ15N of EM and non-EM species, rather than use of different N sources by species with different root specialisations. In support of this notion, δ15N of soil and leaves in the rainforest were similar for E. grandis and co-occurring non-mycorrhizal Proteaceae. In contrast, in wallum forest, E. racemosa leaves and roots were strongly 15N-depleted relative to wallum soil and Proteaceae leaves. We conclude that foliar δ15N may be used in conjunction with other ecosystem information as a rapid indicator of plant dependency on EM associations for N acquisition.

2021 ◽  
Author(s):  
Robert Reuter ◽  
Olga Ferlian ◽  
Mika Tarkka ◽  
Nico Eisenhauer ◽  
Karin Pritsch ◽  
...  

Abstract Mycorrhizal fungi play an important role for the nitrogen (N) supply of trees. The influence of different mycorrhizal types on N acquisition in tree-tree interactions is, however, not well understood, particularly with regard to the competition for growth-limiting N. We studied the effect of competition between temperate forest tree species on their inorganic and organic N acquisition in relation to their mycorrhizal type (i.e., arbuscular mycorrhiza or ectomycorrhiza). In a field experiment, we quantified net N uptake capacity from inorganic and organic N sources using 15N/13C stable isotopes for arbuscular mycorrhizal tree species (i.e., Acer pseudoplatanus L., Fraxinus excelsior L., and Prunus avium L.) as well as ectomycorrhizal tree species (i.e., Carpinus betulus L., Fagus sylvatica L., and Tilia platyphyllos Scop.). All species were grown in intra- and interspecific competition (i.e., monoculture or mixture). Our results showed that N sources were not used complementarily depending on a species´ mycorrhizal association, but their uptake rather depended on the competitor indicating species-specific effects. Generally, ammonium was preferred over glutamine and glutamine over nitrate. In conclusion, our findings suggest that inorganic and organic N acquisition of the studied temperate tree species is less regulated by mycorrhizal association, but rather by the availability of specific N sources in the soil as well as the competitive environment of different tree species.


2020 ◽  
Vol 11 ◽  
Author(s):  
Xuan Jia ◽  
Chaohe Huangfu ◽  
Dafeng Hui

Plant species may acquire different forms of nitrogen (N) to reduce competition for the same resource, but how plants respond to neighbors with different densities in their N uptake is still poorly understood. We investigated the effects of competition regime on the uptake of different N forms by two hygrophytes, Carex thunbergii and Polygonum criopolitanum, by conducting a hydroponic test of excised roots and an in situ experiment in a subtropical wetland ecosystem. The two species were grown either in monocultures or mixtures with various neighbor densities. Root functional traits and N uptake rates of different N forms were measured. Our results showed that N uptake was mainly determined by N form, rather than species identity. Both species were able to use organic N sources, but they took up relatively more N supplied as NO3- than as NH4+ or glycine, irrespective of competition treatments. Both species preferred NO3- when grown in monoculture, but in the presence of competitors, the preference of fast-growing C. thunbergii persisted while P. criopolitanum acquired more NH4+ and glycine, with stronger responses being observed at the highest neighbor density. The hydroponic test suggested that these divergences in N acquisition between two species might be partially explained by different root functional traits. To be specific, N uptake rates were significantly positively correlated with root N concentration and specific root length, but negatively correlated with root dry matter content. Our results implicated that C. thunbergii has a competitive advantage with relatively more stable N acquisition strategy despite a lower N recovery than P. criopolitanum, whereas P. criopolitanum could avoid competition with C. thunbergii via a better access to organic N sources, partly mediated by competition regimes.


Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 123-128
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres ◽  
...  

Abstract 4-O-methylglucuronoxylans isolated from Eucalyptus grandis and Eucalyptus urophylla kraft black liquors (KBLs) were chemically characterized by Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), and nuclear magnetic resonance (NMR) spectroscopy. Doses of alkali charge, expressed as active alkali (AA), were 16, 17, and 18% while the sulfidity was kept at 25%. Kappa numbers of 19.1, 17.5, and 16.1 for E. grandis and 20.4, 16.8, and 15.4 for E. urophylla were obtained. At higher alkali charges, the recovery of xylans from the KBLs was lower and the degree of substitution of xylans with uronic acids decreased. The average molecular weight (Mw) of the recovered xylans was greater under conditions of mild pulping, i.e., in the case of pulps with higher kappa numbers. Mw of xylans ranged from 16.1 to 19.1 kDa for E. grandis and from 15.4 to 20.4 kDa for E. urophylla. The xylans from KBL may be useful as pulp modifying agents or as a raw material for advanced applications.


2020 ◽  
Author(s):  
Nana Yaw Sarpong ◽  
Frank Ofori Agyemang ◽  
Daniel E.K.A Siaw ◽  
Essakku Menason

Abstract BackgroundIncreasing global wood demands have necessitated an overall push for cost-effective methods of vegetative propagation using cuttings. Vegetative plant propagation through cuttings although a breakthrough is mostly hampered with the inability of cuttings to root effectively to achieve maximum yield. Ten clones each of Eucalyptus grandis x Eucalyptus urophylla (E. grandis x E. urophylla) and Eucalyptus pellita (E. pellita) were treated with Indole-3-butyric acid (IBA) concentrations of 0 ppm (control), 2000 ppm, 3000 ppm and 4000 ppm respectively.ResultsOverall mean survival of cuttings was low (< 50%) for all concentrations of IBA used in this research. Survival rates of individual clones however varied from clone to clone. E. grandis x E. urophylla cuttings had the highest mean survival (43.39%) when treated with 2000 ppm of IBA and lowest mean survival (37.86%) when treated with 0 ppm. Results from the survival rates of E. grandis × E. Urophylla and Eucalyptus pellita cuttings were subjected to an Analysis of Variance test to identify any significant differences between hormone concentration and cutting survival. ANOVA results indicated that differences between cutting–IBA concentrations for E. grandis × E. Urophylla were significant (p=1.85x10-08) which is lower than standard p value (p=0.05) used in the test.For E. pellita (P) cuttings the highest mean survival (27.14%) was achieved when treated with 2000 ppm of Indole-3-butyric acid (IBA). Individual clones however showed significant differences in survival. E. pellita clone P2 achieved the highest survival (52.68%) in the control experiment (0 ppm). Some clones i.e P51 and P82 achieved survivals of less than 10% in all four levels of IBAConclusionThe best surviving Eucalyptus grandis x Eucalyptus urophylla clone (GH11) achieved a mean survival rate of 75% when the GH11 basal cutting was treated with 2000 ppm IBA. The results indicated that the production of clones with survival rates of less than 20% should be discarded since it makes no economic sense clones with survival rates of more than 40% should be planted out in the field to compare field performance with greenhouse survival.


2013 ◽  
Vol 373 (1-2) ◽  
pp. 955-965 ◽  
Author(s):  
Stephen D. LeDuc ◽  
David E. Rothstein ◽  
Zhanna Yermakov ◽  
Susan E. Spaulding

Soil Research ◽  
1998 ◽  
Vol 36 (2) ◽  
pp. 217 ◽  
Author(s):  
M. J. Noonan ◽  
M. Zaman ◽  
K. C. Cameron ◽  
H. J. Di

An open incubation and leaching study was conducted under controlled temperature (25°C) and moisture conditions to measure the N mineralisation rate in soil amended with dairy pond sludge. The dairy pond sludge was applied at 3 different rates equivalent to 0, 200, and 400 kg N/ha. The incubation was conducted at 3 different soil moisture potentials (0, -3, and -13 kPa). Following each 2-week period of incubation, the soil was leached with 2 pore volumes of deionised water to remove the mineralisation products. Mineralisation products in the leachate and enzyme activities, microbial biomass C and N, pH, and water-soluble C in the soil were determined. The incubation lasted 18 weeks. Rapid release of nitrate occurred during the first 6 weeks of incubation, followed by a slow release over the remainder of the incubation period. Although the total amount of N released in the 200 kg N/ha treatment (169 mg N/kg soil) was less than in the 400 kg N/ha treatment (206 mg N/kg soil), when expressed as a percentage of the organic N applied, the amount of N released at the lower rate (18·4%) was greater than that at the higher rate of sludge treatment (13·0%). Rapid nitrification decreased the soil leachate ammonium concentration and the soil pH. Soil microbial biomass, water-soluble C, and deaminase activity were significantly increased after the addition of dairy pond sludge. The increase in soil microbial biomass observed was probably due to the increased water-soluble C and nutrients that stimulated the soil microbial growth. The rapid N release and nitrification rates observed were attributed to the low C : N ratio (12·7), high ammonium content (145 mg N/kg) of the dairy pond sludge used, and the optimum moisture and temperature conditions. The narrow range of soil water potential conditions did not have any significant effect on N release rate or amount.


Toxins ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 724
Author(s):  
Siyi Tao ◽  
Suqin Wang ◽  
Lirong Song ◽  
Nanqin Gan

Cyanotoxins are the underlying cause of the threat that globally pervasive Cyanobacteria Harmful algal blooms (CyanoHABs) pose to humans. Major attention has been focused on the cyanobacterial hepatotoxin microcystins (MCs); however, there is a dearth of studies on cyanobacterial neurotoxin anatoxins. In this study, we explored how an anatoxin-producing Cuspidothrix issatschenkoi strain responded to culture with inorganic and organic nitrogen sources in terms of growth and anatoxins production. The results of our study revealed that ʟ- alanine could greatly boost cell growth, and was associated with the highest cell productivity, while urea significantly stimulated anatoxin production with the maximum anatoxin yield reaching 25.86 μg/mg dry weight, which was 1.56-fold higher than that in the control group (BG11). To further understand whether the carbon/nitrogen balance in C. issatschenkoi would affect anatoxin production, we explored growth and toxin production in response to different carbon/nitrogen ratios (C/N). Anatoxin production was mildly promoted when the C/N ratio was within low range, and significantly inhibited when the C/N ratio was within high range, showing approximately a three-fold difference. Furthermore, the transcriptional profile revealed that anaC gene expression was significantly up-regulated over 2–24 h when the C/N ratio was increased, and was significantly down-regulated after 96 h. Overall, our results further enriched the evidence that urea can stimulate cyanotoxin production, and ʟ-alanine could boost C. issatschenkoi proliferation, thus providing information for better management of aquatic systems. Moreover, by focusing on the intracellular C/N metabolic balance, this study explained the anatoxin production dynamics in C. issatschenkoi in response to different N sources.


2020 ◽  
Vol 71 (15) ◽  
pp. 4469-4479 ◽  
Author(s):  
Alia Dellagi ◽  
Isabelle Quillere ◽  
Bertrand Hirel

Abstract Nitrogen (N) is an essential element for plant productivity, thus, it is abundantly applied to the soil in the form of organic or chemical fertilizers that have negative impacts on the environment. Exploiting the potential of beneficial microbes and identifying crop genotypes that can capitalize on symbiotic associations may be possible ways to significantly reduce the use of N fertilizers. The best-known example of symbiotic association that can reduce the use of N fertilizers is the N2-fixing rhizobial bacteria and legumes. Bacterial taxa other than rhizobial species can develop associative symbiotic interactions with plants and also fix N. These include bacteria of the genera Azospirillum, Azotobacter, and Bacillus, some of which are commercialized as bio-inoculants. Arbuscular mycorrhizal fungi are other microorganisms that can develop symbiotic associations with most terrestrial plants, favoring access to nutrients in a larger soil volume through their extraradical mycelium. Using combinations of different beneficial microbial species is a promising strategy to boost plant N acquisition and foster a synergistic beneficial effect between symbiotic microorganisms. Complex biological mechanisms including molecular, metabolic, and physiological processes dictate the establishment and efficiency of such multipartite symbiotic associations. In this review, we present an overview of the current knowledge and future prospects regarding plant N nutrition improvement through the use of beneficial bacteria and fungi associated with plants, individually or in combination.


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