Abstract
SUMMARY We investigated the effect of soil compaction and phosphorus (P) application on morphological characteristics of mycorrhizal colonization and growth responses, to determine the reasons for reduced responses observed in our previous work with compacted soil. Growth, phosphorus (P) uptake and intensity of vesicular–arbuscular (VA) mycorrhizal colonization were studied in clover plants ( Trifolium subterraneum L.) with and without VA mycorrhizal colonization at two P applications and three levels of soil compaction. Phosphorus was supplied either at constant mass concentration (mg P kg −1 soil) or at constant volume concentration (mg P dm −3 soil). Increasing bulk density of the soil from 1·1 to 1.6 Mg m −3 significantly decreased root length and shoot d. wt, but increased the diameter of both main axes and first order lateral roots regardless of P application. Total P uptake and shoot d. wt of clover plants colonized by Glomus intraradices (Schenck & Smith) were significantly greater than those of non‐mycorrhizal plants at all levels of soil compaction and both P applications. However, soil compaction to a bulk density of 1.6 Mg m −3 (penetrometer resistance = 3.5 MPa at a matric potential of − 33 kPa) significantly decreased mycorrhizal growth response. There was no evidence that the increased volume concentration of P at high bulk densities was responsible for the reduced responses. Soil compaction had no significant effect on the fraction of root length containing arbuscules and vesicles, but total root length colonized by arbuscules, vesicles or by any combination of arbuscules, vesicles and intra‐radical hyphae significantly decreased as soil compaction was increased. The air‐filled porosity of highly compacted soil, which varied from 0.07 to 0.11 over the range of matric potentials encountered (− 33 and − 100 kPa), had no significant effect on the intensity of internal colonization.
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Claims 8
Claim · model-written summary
Increasing soil bulk density significantly decreased root length and shoot dry weight of Trifolium subterraneum.
- Taxon
- Trifolium subterraneum
Trifolium subterraneumt0 - Treatment
- Increasing bulk density of the soile0
- Outcome
- root length and shoot d. wte1
- Direction
- decreasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e0“Increasing bulk density of the soil”
e1“significantly decreased root length and shoot d. wt”
Claim · model-written summary
Increasing soil bulk density increased the root diameter of both main axes and first order lateral roots of Trifolium subterraneum regardless of P application.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- Increasing bulk density of the soile0
- Outcome
- diameter of both main axes and first order lateral rootse2
- Direction
- increasede2
- Qualifier
- regardless of P applicatione2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e0“Increasing bulk density of the soil”
e2“increased the diameter of both main axes and first order lateral roots regardless of P application”
Claim · model-written summary
Total P uptake and shoot dry weight of Trifolium subterraneum colonized by Glomus intraradices were significantly greater than those of non-mycorrhizal plants.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- colonized by Glomus intraradicese3
- Interactor
- Glomus intraradicesRhizophagus intraradicese3symbiont
- Outcome
- Total P uptake and shoot d. wte3
- Direction
- greatere4
- Comparator
- non‐mycorrhizal plantse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e3“Total P uptake and shoot d. wt of clover plants colonized by Glomus intraradices”
e4“were significantly greater than those of non‐mycorrhizal plants”
Claim · model-written summary
Soil compaction to a bulk density of 1.6 significantly decreased the mycorrhizal growth response of Trifolium subterraneum.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- soil compaction to a bulk densitye5
- Interactor
- Glomus intraradicesRhizophagus intraradicese3symbiont
- Outcome
- mycorrhizal growth responsee6
- Direction
- decreasede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e3“Total P uptake and shoot d. wt of clover plants colonized by Glomus intraradices”
e5“soil compaction to a bulk density”
e6“significantly decreased mycorrhizal growth response”
Claim · model-written summary
Soil compaction had no significant effect on the fraction of root length containing arbuscules and vesicles in Trifolium subterraneum.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- Soil compactione7
- Outcome
- fraction of root length containing arbuscules and vesiclese7
- Direction
- no significant effecte7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e7“Soil compaction had no significant effect on the fraction of root length containing arbuscules and vesicles”
Claim · model-written summary
Total root length colonized by arbuscules, vesicles or intra-radical hyphae decreased significantly as soil compaction increased.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- soil compactione2
- Outcome
- total root length colonized by arbusculese1
- Direction
- decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e1“total root length colonized by arbuscules, vesicles or by any combination”
e2“significantly decreased as soil compaction was increased”
Claim · model-written summary
Highly compacted soil had no significant effect on the intensity of internal mycorrhizal colonization of Trifolium subterraneum.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- highly compacted soile1
- Outcome
- intensity of internal colonizatione2
- Direction
- no significant effecte2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e1“of highly compacted soil, which varied from 0.07 to 0.11”
e2“had no significant effect on the intensity of internal colonization”
Claim · model-written summary
The increased volume concentration of P at high bulk densities was not responsible for the reduced mycorrhizal responses.
- Taxon
- Trifolium subterraneumTrifolium subterraneumt0
- Treatment
- increased volume concentration of Pe1
- Outcome
- reduced responsese1
- Direction
- reducede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“colonization of Trifolium subterraneum”
e1“There was no evidence that the increased volume concentration of P at high bulk densities was responsible for the reduced responses”
The same questions in other papers
tillage · Rhizophagus intraradices · Trifolium subterraneumResults agree
1 paper in the same direction as this paper
- no effect
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.