Abstract
To eliminate the negative effect of soil contamination with heavy metals on plant growth and crop yield, different methods and techniques are the subject of discussion and study. In this study, we aimed to evaluate the effect of secondary pulp and paper-mill sludge application to soil on the response of the main physiological processes such as the growth, photosynthesis, and respiration of lettuce (Lactuca sativa L.) plants to soil contamination with Pb. For the pot experiment, Pb was added to sandy loam soil at concentrations of 0, 50, and 250 mg Pb(NO3)2 per kg of the soil, and secondary sludge was added to a 0, 20, or 40% sludge solution during each plant watering. The Pb-mediated change in plant biomass allocation, decrease in the photosynthetic rate, increase in leaf respiration rate, and the degree of light inhibition of respiration were closely associated with increases in both root and shoot Pb content. For the Pb-free soil condition, secondary sludge application contributed to the allocation of plant biomass towards a greater accumulation in the shoots than in the roots. Although stomatal opening was not affected by either Pb or sludge, sludge application increased photosynthetic CO2 assimilation regardless of soil Pb content, which was associated with an increase in the electron-transport rate and carboxylase activity of Rubisco. Soil contamination with Pb significantly increased the ratio of respiration to photosynthesis, reflecting a shift in the carbon balance toward carbon losses in the leaves, but sludge application modified the coupling between the processes with a decrease in the proportion of respiratory carbon losses. The sludge-mediated recovery of the physiological processes of L. sativa reflected an increase in plant tolerance to soil contamination with heavy metals, the formation of which is associated with plant and soil adjustments initiated by secondary sludge application.
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Claims 10
Claim · model-written summary
Lead related biomass allocation changes, lower photosynthesis, higher respiration and light inhibition tracked root and shoot Pb content.
- Taxon
- Lactuca sativa L.
Lactuca sativat0 - Compound
- Pb contente0
- Outcome
- plant biomass allocatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Pb-mediated change in plant biomass allocation, decrease in the photosynthetic rate, increase in leaf respiration rate, and the degree of light inhibition of respiration were closely associated with increases in both root and shoot Pb content”
t0“Lactuca sativa L.”
Claim · model-written summary
Higher root and shoot Pb content was associated with decreased photosynthetic rate.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Compound
- Pb contente0
- Outcome
- photosynthetic ratee0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decrease in the photosynthetic rate, increase in leaf respiration rate, and the degree of light inhibition of respiration were closely associated with increases in both root and shoot Pb content”
t0“Lactuca sativa L.”
Claim · model-written summary
Higher root and shoot Pb content was associated with increased leaf respiration rate.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Compound
- Pb contente0
- Outcome
- leaf respiration ratee0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increase in leaf respiration rate, and the degree of light inhibition of respiration were closely associated with increases in both root and shoot Pb content”
t0“Lactuca sativa L.”
Claim · model-written summary
In lead free soil sludge shifted biomass accumulation toward shoots.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Treatment
- secondary sludge applicatione0
- Outcome
- accumulation in the shootse0
- Direction
- greatere0
- Comparator
- rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the Pb-free soil condition, secondary sludge application contributed to the allocation of plant biomass towards a greater accumulation in the shoots than in the roots”
t0“Lactuca sativa L.”
Claim · model-written summary
Neither lead nor sludge affected stomatal opening.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Treatment
- Pb or sludgee0
- Outcome
- stomatal openinge0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal opening was not affected by either Pb or sludge”
t0“Lactuca sativa L.”
Claim · model-written summary
Sludge increased photosynthetic CO2 assimilation regardless of soil Pb.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Treatment
- sludge applicatione0
- Outcome
- photosynthetic CO2 assimilatione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sludge application increased photosynthetic CO2 assimilation regardless of soil Pb content”
t0“Lactuca sativa L.”
Claim · model-written summary
Increased photosynthetic assimilation with sludge was associated with higher electron transport and Rubisco carboxylase activity.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Gene
- Rubiscoe0
- Outcome
- electron-transport rate and carboxylase activity of Rubiscoe0
- Direction
- increasee0
- Qualifier
- associatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which was associated with an increase in the electron-transport rate and carboxylase activity of Rubisco”
t0“Lactuca sativa L.”
Claim · model-written summary
Lead significantly increased the respiration to photosynthesis ratio.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Treatment
- Soil contamination with Pbe0
- Outcome
- ratio of respiration to photosynthesise0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil contamination with Pb significantly increased the ratio of respiration to photosynthesis”
t0“Lactuca sativa L.”
Claim · model-written summary
Sludge reduced the proportion of respiratory carbon losses.
- Taxon
- Lactuca sativa L.Lactuca sativat0
- Treatment
- sludge applicatione0
- Outcome
- proportion of respiratory carbon lossese0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sludge application modified the coupling between the processes with a decrease in the proportion of respiratory carbon losses”
t0“Lactuca sativa L.”
Claim · model-written summary
Sludge mediated physiological recovery reflected greater tolerance to heavy metal contaminated soil.
- Taxon
- L. sativaLactuca sativae0
- Treatment
- secondary sludge applicatione0
- Outcome
- plant tolerance to soil contamination with heavy metalse0
- Direction
- increasee0
- Qualifier
- plant and soil adjustmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The sludge-mediated recovery of the physiological processes of L. sativa reflected an increase in plant tolerance to soil contamination with heavy metals, the formation of which is associated with plant and soil adjustments initiated by secondary sludge application”
The same questions in other papers
lead atom · physiology: gas exchange · Lactuca sativa (garden lettuce)Results agree
1 paper in the same direction as this paper
- no effect
lead atom · physiology: photosynthesis · Lactuca sativa (garden lettuce)Results agree
3 papers in the same direction as this paper
- negative
- negative
- no effect
organic · molecular: metabolites · Lactuca sativa (garden lettuce)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- positive
2 papers more in this group
See all 6 papers →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.