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Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions

View Article: PubMed Central - PubMed

ABSTRACT

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

No MeSH data available.


The evolution of total PLFA (a) and PLFA biomarker concentrations of the major microbial groups G+ve, G−ve bacteria and actinomycetes (b), Saprophytic fungi and AMF (c) and protozoa nad FB ratio (d) over time in +Nem and −Nem treatments.The asterisk symbol (*) indicates statistically significant differences between treatments on the corresponding sampling dates.
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f2: The evolution of total PLFA (a) and PLFA biomarker concentrations of the major microbial groups G+ve, G−ve bacteria and actinomycetes (b), Saprophytic fungi and AMF (c) and protozoa nad FB ratio (d) over time in +Nem and −Nem treatments.The asterisk symbol (*) indicates statistically significant differences between treatments on the corresponding sampling dates.

Mentions: The mean microbial biomass C (Cmic) in the +Nem treatment was not significantly different (p = 0.178) from −Nem (Table 1). Total PLFA concentration tended to be higher in +Nem treatments than −Nem treatments during most of the incubation period with significant differences on day 24 (+19.65 nmol g−1 dry soil, p = 0.025) and 47 (+20.04 nmol g−1 dry soil, p = 0.021) (Fig. 2a). No significant interactions were observed between incubation time and nematode treatments for bacterial and actinomycetes communities (Table S4). No significant differences were found in average abundances over time, between +Nem and −Nem treatments for marker PLFAs of Gram-positive (p = 0.959), Gram-negative (p = 0.337) and actinomycetes (p = 0.784). Saprophytic fungi marker PLFA concentrations were significantly higher in +Nem than −Nem on day 24 (+6.90 nmol g−1soil, p = 0.000) and 47 (+6.12 nmol g−1 soil, p = 0.000) and AMF biomarkers on day 67 (+0.40 nmol g−1 soil, p = 0.002) and on day 105 (+0.71 nmol g−1 soil, p = 0.000) (Fig. 2c). As for the fungal marker PLFAs, the F:B ratio was significantly higher in +Nem than −Nem treatment on day 24 and day 47. Protozoa marker PLFA concentrations were significantly higher in +Nem than −Nem treatments on day 47 (+0.18 nmol g−1 soil, p = 0.004) and on the last day of incubation (+0.28 nmol g−1 soil, p = 0.000) (Fig. 2d).


Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions
The evolution of total PLFA (a) and PLFA biomarker concentrations of the major microbial groups G+ve, G−ve bacteria and actinomycetes (b), Saprophytic fungi and AMF (c) and protozoa nad FB ratio (d) over time in +Nem and −Nem treatments.The asterisk symbol (*) indicates statistically significant differences between treatments on the corresponding sampling dates.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015107&req=5

f2: The evolution of total PLFA (a) and PLFA biomarker concentrations of the major microbial groups G+ve, G−ve bacteria and actinomycetes (b), Saprophytic fungi and AMF (c) and protozoa nad FB ratio (d) over time in +Nem and −Nem treatments.The asterisk symbol (*) indicates statistically significant differences between treatments on the corresponding sampling dates.
Mentions: The mean microbial biomass C (Cmic) in the +Nem treatment was not significantly different (p = 0.178) from −Nem (Table 1). Total PLFA concentration tended to be higher in +Nem treatments than −Nem treatments during most of the incubation period with significant differences on day 24 (+19.65 nmol g−1 dry soil, p = 0.025) and 47 (+20.04 nmol g−1 dry soil, p = 0.021) (Fig. 2a). No significant interactions were observed between incubation time and nematode treatments for bacterial and actinomycetes communities (Table S4). No significant differences were found in average abundances over time, between +Nem and −Nem treatments for marker PLFAs of Gram-positive (p = 0.959), Gram-negative (p = 0.337) and actinomycetes (p = 0.784). Saprophytic fungi marker PLFA concentrations were significantly higher in +Nem than −Nem on day 24 (+6.90 nmol g−1soil, p = 0.000) and 47 (+6.12 nmol g−1 soil, p = 0.000) and AMF biomarkers on day 67 (+0.40 nmol g−1 soil, p = 0.002) and on day 105 (+0.71 nmol g−1 soil, p = 0.000) (Fig. 2c). As for the fungal marker PLFAs, the F:B ratio was significantly higher in +Nem than −Nem treatment on day 24 and day 47. Protozoa marker PLFA concentrations were significantly higher in +Nem than −Nem treatments on day 47 (+0.18 nmol g−1 soil, p = 0.004) and on the last day of incubation (+0.28 nmol g−1 soil, p = 0.000) (Fig. 2d).

View Article: PubMed Central - PubMed

ABSTRACT

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

No MeSH data available.