Abstract
Abstract Addition of heavy metals to soils from sources such as biosolid application, smelter emissions, fertilizers, and the like may produce soil solution concentrations of Zn and Cd that can potentially restrict nodulation of legume crops such as white clover. To assess the effects of Zn and Cd on the early stages of nodulation of white clover, a solution culture study was conducted. Rhizobia [ Rhizobium leguminosarum bv. trifolii ] of a metal‐sensitive strain (USDA 2063) and a metal‐tolerant strain (USDA 2046) were inoculated into nutrient solution with white clover seedlings containing EGTA to buffer Zn 2+ and Cd 2+ activities. The calculated activities of Zn 2+ were p = 8.00, 5.70, 5.25, and 5.00; the calculated activities of Cd 2+ were p = 10.50, 9.50, 8.75, and 8.50. Phase‐contrast microscopy was used after staining roots with methylene blue to observe root hair infection at intervals of 1, 12, 24, 72, and 168 h. Few differences were observed between the sensitive and tolerant rhizobial strains. At the lowest Zn concentration, initial attachment of bacteria to root hairs was observed within 1 h. At the highest Zn concentration, attachment was not observed until 12 h. Also, at the highest Zn concentration, a delay was observed for up to 60 h and 4 d, respectively, for the first signs of root hair curling and infection thread formation. Shoot weight decreased with increasing Zn concentration. Few Cd‐induced effects on early stages of nodule development were observed. Cadmium was more toxic to plant growth than Zn. These results show that in addition to direct effects on the macro and microsymbiont, the process of nodulation is susceptible to the toxic effects of heavy metals.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 8
Claim · model-written summary
Few differences in nodulation responses were observed between metal-sensitive and tolerant rhizobial strains.
- Taxon
- white clover
Trifolium repenst0 - Outcome
- Few differencese0
- Comparator
- sensitive and tolerant rhizobial strainse0
Not reportedInteractorInteractor role
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Few differences were observed between the sensitive and tolerant rhizobial strains.”
t0“White Clover”
Claim · model-written summary
At the lowest zinc concentration, rhizobia attached to root hairs within one hour.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- lowest Zn concentratione0
- Outcome
- initial attachment of bacteria to root hairse0
- Value
- 1 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the lowest Zn concentration, initial attachment of bacteria to root hairs was observed within 1 h.”
t0“White Clover”
Claim · model-written summary
At the highest zinc concentration, bacterial attachment to root hairs was not observed until 12 hours.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- highest Zn concentratione0
- Outcome
- attachmente0
- Value
- 12 he0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the highest Zn concentration, attachment was not observed until 12 h.”
t0“White Clover”
Claim · model-written summary
The highest zinc concentration delayed root hair curling by up to 60 hours.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- highest Zn concentratione0
- Outcome
- root hair curlinge0
- Direction
- delaye0
- Value
- 60 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at the highest Zn concentration, a delay was observed for up to 60 h and 4 d, respectively, for the first signs of root hair curling and infection thread formation”
t0“White Clover”
Claim · model-written summary
The highest zinc concentration delayed infection thread formation by up to four days.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- highest Zn concentratione0
- Outcome
- infection thread formatione0
- Direction
- delaye0
- Value
- 4 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at the highest Zn concentration, a delay was observed for up to 60 h and 4 d, respectively, for the first signs of root hair curling and infection thread formation”
t0“White Clover”
Claim · model-written summary
Shoot weight decreased as zinc concentration increased.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- Zn concentratione0
- Outcome
- Shoot weighte0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot weight decreased with increasing Zn concentration.”
t0“White Clover”
Claim · model-written summary
Cadmium had few effects on early nodule development.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- Cde0
- Outcome
- early stages of nodule developmente0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Few Cd‐induced effects on early stages of nodule development were observed.”
t0“White Clover”
Claim · model-written summary
Cadmium was more toxic to plant growth than zinc.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- Cadmiume0
- Outcome
- plant growthe0
- Direction
- more toxice0
- Comparator
- Zne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cadmium was more toxic to plant growth than Zn.”
t0“White Clover”
The same questions in other papers
zinc atom · growth · Trifolium repens (white clover)Positive and negative results
1 in the opposite direction
- positive
cadmium atom · growth · Trifolium repens (white clover)Positive and negative results
8 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- no effect
7 papers more in this group
See all 11 papers →cadmium atom · symbiosis · Trifolium repens (white clover)Results agree
1 paper in the same direction as this paper
- negative
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.