Abstract
The relationship between Pb uptake by leaf lettuce ( Lactuca sativa L.) and water-soluble low-molecular-weight organic acids (LMWOAs) in rhizosphere, as influenced by transpiration (high and low), has been studied. Studies were carried out by culturing lettuce plants grown for 2 weeks in pots filled with quartz sand mixed with anion-exchange resin and then for 30 days in a greenhouse. The potted lettuce plants were subjected to stress by the addition of Pb(NO 3) 2 solutions (100, 200, and 300 mg of Pb L (-1)) and by high and low transpiration treatments for another 10-day period. Blank experiments (without addition of Pb(NO 3) 2 solutions to the pots) were also run. There were no significant differences in the growth of the plants with the addition of Pb(NO 3) 2 solutions in either of the transpirations studies. Uptake of Pb by the shoots and roots of the plants was found to be proportional to the concentration of Pb solutions added, and more accumulation was observed in the roots than in the shoots at the end of days 3 and 10. High transpiration caused more Pb uptake than did low transpiration. One volatile acid (propionic acid) and nine nonvolatile acids (lactic, glycolic, oxalic, succinic, fumaric, oxalacetic, d-tartaric, trans-aconitic, and citric acids) in rhizosphere quartz sand or anion-exchange resin were identified and quantified by gas chromatography analysis with a flame ionization detector. The amount of LMWOAs in rhizosphere quartz sand or anion-exchange resin increased with higher amounts of Pb in quartz sand solution and also with longer duration of the study. The total quantities of the LMWOAs in the rhizosphere quartz sand or anion-exchange resin were significantly higher under high and low transpiration with a 300 mg of Pb L (-1) solution addition at the end of day 10. Compared with our previous related studies (published work), the present study shows that the presence of LMWOAs in rhizosphere does not significantly affect Pb uptake by lettuce plants under high and low transpiration. A physiological mechanism of the roots of lettuce plants governing the relationship between Pb contamination level and quantity of water-soluble LMWOAs in rhizosphere quartz sand and resin, as influenced by transpiration, was proposed.
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Claims 9
Claim · model-written summary
Adding Pb solutions caused no significant differences in lettuce growth at either transpiration rate.
- Taxon
- Lettuce
Lactuca sativat0 - Treatment
- addition of Pbe0
- Outcome
- growth of the plantse0
- Direction
- no significant differencese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“There were no significant differences in the growth of the plants with the addition of Pb”
Claim · model-written summary
Pb uptake by lettuce shoots and roots was proportional to the concentration of Pb solution added.
- Taxon
- LettuceLactuca sativat0
- Treatment
- concentration of Pb solutions addede0
- Outcome
- Uptake of Pb by the shoots and rootse0
- Direction
- proportionale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“Uptake of Pb by the shoots and roots of the plants was found to be proportional to the concentration of Pb solutions added”
Claim · model-written summary
More Pb accumulated in lettuce roots than in shoots at the end of days 3 and 10.
- Taxon
- LettuceLactuca sativat0
- Organ / stage
- rootse0
- Outcome
- accumulatione0
- Direction
- moree0
- Comparator
- shootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“more accumulation was observed in the roots than in the shoots at the end of days 3 and 10”
Claim · model-written summary
High transpiration caused more Pb uptake by lettuce than low transpiration.
- Taxon
- LettuceLactuca sativat0
- Treatment
- High transpiratione0
- Outcome
- Pb uptakee0
- Direction
- moree0
- Comparator
- low transpiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“High transpiration caused more Pb uptake than did low transpiration”
Claim · model-written summary
One volatile acid (propionic acid) and nine nonvolatile acids (lactic, glycolic, oxalic, succinic, fumaric, oxalacetic, d-tartaric, trans-aconitic and citric acids) were identified and quantified in the rhizosphere quartz sand or anion-exchange resin.
- Taxon
- LettuceLactuca sativat0
- Outcome
- One volatile acid (propionic acid) and nine nonvolatile acidse0
- Setting
- rhizosphere quartz sand or anion-exchange resine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“One volatile acid (propionic acid) and nine nonvolatile acids (lactic, glycolic, oxalic, succinic, fumaric, oxalacetic, d-tartaric, trans-aconitic, and citric acids) in rhizosphere quartz sand or anion-exchange resin were identified and quantified”
Claim · model-written summary
The amount of LMWOAs in the rhizosphere increased with higher amounts of Pb in the quartz sand solution.
- Taxon
- LettuceLactuca sativat0
- Treatment
- higher amounts of Pb in quartz sand solutione0
- Outcome
- amount of LMWOAs in rhizosphere quartz sand or anion-exchange resine0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“The amount of LMWOAs in rhizosphere quartz sand or anion-exchange resin increased with higher amounts of Pb in quartz sand solution and also with longer duration of the study”
Claim · model-written summary
The amount of LMWOAs in the rhizosphere increased with longer duration of the study.
- Taxon
- LettuceLactuca sativat0
- Treatment
- longer duration of the studye0
- Outcome
- amount of LMWOAs in rhizosphere quartz sand or anion-exchange resine0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“The amount of LMWOAs in rhizosphere quartz sand or anion-exchange resin increased with higher amounts of Pb in quartz sand solution and also with longer duration of the study”
Claim · model-written summary
Total LMWOA quantities in the rhizosphere were significantly higher with the 300 mg Pb L-1 solution at the end of day 10 under both high and low transpiration.
- Taxon
- LettuceLactuca sativat0
- Treatment
- 300 mg of Pb L (-1) solution additione0
- Outcome
- total quantities of the LMWOAse0
- Direction
- highere0
- Qualifier
- high and low transpiratione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“The total quantities of the LMWOAs in the rhizosphere quartz sand or anion-exchange resin were significantly higher under high and low transpiration with a 300 mg of Pb L (-1) solution addition at the end of day 10”
Claim · model-written summary
The presence of LMWOAs in the rhizosphere does not significantly affect Pb uptake by lettuce under high and low transpiration.
- Taxon
- LettuceLactuca sativat0
- Compound
- LMWOAse0
- Outcome
- Pb uptakee0
- Direction
- does not significantly affecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lettuce”
e0“the present study shows that the presence of LMWOAs in rhizosphere does not significantly affect Pb uptake by lettuce plants under high and low transpiration”
The same questions in other papers
lead atom · growth · Lactuca sativa (garden lettuce)Results differ
7 papers in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
7 papers more in this group
See all 11 papers →lead atom · molecular: metabolites · Lactuca sativa (garden lettuce)Positive and negative results
3 in the opposite direction
- no effect
- negative
- 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.