Abstract
Tropical soils are highly-weathered acidic soils and frequently present two intersecting problems that can be detrimental to plant development: low phosphorus (P) and high manganese (Mn) availability. Mn can be phytotoxic, damaging the photosynthetic apparatus and/or competing with other nutrients. Eucalyptus grandis is often cultivated in such soil types and, despite being a tree generally tolerant to Mn excess, P deficiency may exacerbate toxicity. Arbuscular mycorrhizal (AM) fungi are known for their ability to provide P to the host plant in exchange of photosynthates. This symbiosis may also decrease Mn accumulation and overall alleviate metal stress. In a glasshouse experiment, E. grandis plants were grown for seven months in soil with low P availability adjusted to three Mn dose levels (control, 75 and 150 mg kg–1), with (AM) or without (NM) inoculation with Rhizophagus irregularis. We measured biomass, height, flavonoids (anthocyanin/flavonol) and chlorophyll indexes, chlorophyll a fluorescence parameters, AM colonization and Mn, P, Mg, K and Fe concentrations in shoots and roots. All plants presented low biomass production, and shoot P concentrations ranged from 0.13 to 0.52 g kg–1. Mn additions decreased mycorrhizal colonization, but no other negative impacts were seen in E. grandis, indicating that this species is relatively tolerant to excess Mn. At dose 75, shoots accumulated up to 2,000 mg Mn kg–1; however, this amount was not detrimental to most parameters, especially in NM plants, which had higher growth and Mg concentrations while presenting much lower flavonol and anthocyanin contents. At dose 150, plant Mn concentrations were similar to those at 75 Mn, despite higher soil availability, indicating that shoot concentrations around 2,000 mg kg–1 were a threshold for E. grandis under P deficiency. AM colonization intensity and arbuscule abundance were overall low, resulting in no improvements in P nutrition nor reduction of Mn uptake in high Mn treatments. However, AM symbiosis led to higher chlorophyll contents and non-photochemical quenching values, which are important in withstanding abiotic stress. Even though AM fungi inoculation did not improve P uptake, multivariate analysis suggests that the mycorrhizal pathway influenced nutrient acquisition in AM plants. Our results show that in E. grandis Mn excess had an alleviation and a hormetic effect, mitigating P deficiency stress rather than being phytotoxic. AM symbiosis did not improve mineral nutrition, despite providing some benefits involved in stress tolerance.
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Claims 13
Claim · model-written summary
Plants had low biomass and shoot P of 0.13 to 0.52 g kg–1.
- Taxon
- Eucalyptus grandis
Eucalyptus grandist0 - Outcome
- low biomass productione0
- Value
- 0.13 to 0.52 g kg–1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All plants presented low biomass production, and shoot P concentrations ranged from 0.13 to 0.52 g kg–1”
t0“Eucalyptus grandis”
Claim · model-written summary
Mn additions reduced mycorrhizal colonization.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- Mn additionse0
- Outcome
- mycorrhizal colonizatione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mn additions decreased mycorrhizal colonization”
t0“Eucalyptus grandis”
Claim · model-written summary
Mn additions caused no other negative impacts on Eucalyptus.
- Taxon
- E. grandisEucalyptus grandise0
- Treatment
- excess Mnt0
- Outcome
- negative impactse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no other negative impacts were seen in E. grandis”
t0“excess Mn”
Claim · model-written summary
At dose 75, shoots accumulated up to 2,000 mg Mn kg–1.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- dose 75e0
- Outcome
- shoots accumulatede0
- Value
- 2,000 mg Mn kg–1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At dose 75, shoots accumulated up to 2,000 mg Mn kg–1”
t0“Eucalyptus grandis”
Claim · model-written summary
At dose 75, nonmycorrhizal plants had higher growth and Mg concentrations.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Material
- NM plantse0
- Outcome
- growth and Mg concentrationse0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NM plants, which had higher growth and Mg concentrations”
t0“Eucalyptus grandis”
Claim · model-written summary
At dose 75, nonmycorrhizal plants had lower flavonol and anthocyanin contents.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Material
- NM plantse0
- Outcome
- flavonol and anthocyanin contentse0
- Direction
- much lowere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NM plants, which had higher growth and Mg concentrations while presenting much lower flavonol and anthocyanin contents”
t0“Eucalyptus grandis”
Claim · model-written summary
At dose 150, plant Mn concentrations were similar to dose 75 despite higher soil availability.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- dose 150e0
- Outcome
- plant Mn concentrationse0
- Direction
- similare0
- Comparator
- 75 Mne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At dose 150, plant Mn concentrations were similar to those at 75 Mn, despite higher soil availability”
t0“Eucalyptus grandis”
Claim · model-written summary
AM colonization did not improve P nutrition.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- AM colonizatione0
- Outcome
- P nutritione0
- Direction
- no improvementse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AM colonization intensity and arbuscule abundance were overall low, resulting in no improvements in P nutrition nor reduction of Mn uptake in high Mn treatments”
t0“Eucalyptus grandis”
Claim · model-written summary
AM colonization did not reduce Mn uptake in high Mn treatments.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- AM colonizatione0
- Outcome
- Mn uptakee0
- Direction
- nor reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AM colonization intensity and arbuscule abundance were overall low, resulting in no improvements in P nutrition nor reduction of Mn uptake in high Mn treatments”
t0“Eucalyptus grandis”
Claim · model-written summary
AM symbiosis increased chlorophyll contents and non-photochemical quenching.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- AM symbiosise0
- Outcome
- chlorophyll contents and non-photochemical quenching valuese0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AM symbiosis led to higher chlorophyll contents and non-photochemical quenching values”
t0“Eucalyptus grandis”
Claim · model-written summary
Multivariate analysis suggests a mycorrhizal pathway influenced nutrient acquisition.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- mycorrhizal pathwaye0
- Outcome
- nutrient acquisitione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“multivariate analysis suggests that the mycorrhizal pathway influenced nutrient acquisition in AM plants”
t0“Eucalyptus grandis”
Claim · model-written summary
Mn excess alleviated P deficiency stress.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- Mn excesse0
- Outcome
- P deficiency stresse0
- Direction
- mitigatinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mn excess had an alleviation and a hormetic effect, mitigating P deficiency stress rather than being phytotoxic”
t0“Eucalyptus grandis”
Claim · model-written summary
AM symbiosis did not improve mineral nutrition.
- Taxon
- Eucalyptus grandisEucalyptus grandist0
- Treatment
- AM symbiosise0
- Outcome
- mineral nutritione0
- Direction
- did not improvee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AM symbiosis did not improve mineral nutrition, despite providing some benefits involved in stress tolerance”
t0“Eucalyptus grandis”
The same questions in other papers
mycorrhiza · nutrient: content · Eucalyptus grandis (rose gum)Positive and negative results
1 in the opposite direction
- positive
infection · nutrient: content · Eucalyptus grandis (rose gum)Positive and negative results
1 in the opposite direction
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.