Abstract
The present study was conducted to determine how 10 weeks of root hypoxia and a low P supply altered relative growth, and carbon acquisition and partitioning in a moderately flood tolerant pine. Pond pine ( Pinus serotina Michx.) seedlings were grown in continuously flowing solution culture at 5 or 100 μ M P, under aerobic or hypoxic solution conditions. Staggered harvests were used to ascertain changes in biomass allocation and relative growth over time. Carbon dioxide exchange rates (CER) were determined by infrared gas analysis, and needles were analyzed for inorganic P (Pi), sucrose, reducing sugars and starch. Although aeration treatment had no significant effect on shoot dry weight or shoot ontogeny, root dry weight of hypoxic seedlings was significantly lower than that of aerobic seedliings after 8 weeks, regardless of the P treatment. Mean relative growth rates (RGR) of roots in the high P treatment initially decreased under hypoxia, but recovered by the sixth week with the production of adventitious roots. Two weeks of hypoxic growth conditions decreased CER and stomatal conductances of seedlings in the high P treatment by more than 30% relative to their aerobic counterparts. Stomatal closure was not accompanied by a decrease in intracellular CO 2 , but was accompanied by an increase in starch accumulation. Recoveries of CER, stomatal conductance and carbohydrate metabolism coincided with the recovery of root growth. Low P growth conditions did not significantly affect shoot or root dry weight until the sixth week of treatment. However, differences in seedling RGR, particularly needle RGR, were discernable during the first 2 weeks. Low P treatment effects on CER paralleled changes in needle RGR, with needle RGR more affected than CER. After 6 weeks, CER of aerobically grown seedlings in the low P treatment were only 15% lower than CER of seedlings in the high P treatment, despite a 31% and 75% reduction in needle RGR and Pi concentrations, respectively. Increased starch concentrations of recently expanded needles at this time were probably a result of diminished growth. The inhibitory effect of a low P supply on shoot growth, more specifically on needle expansion and emergence of new fascicular needles, probably limited net carbon fixed per plant more than any direct effect of low P on CER per se.
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Claims 19
Claim · model-written summary
Aeration had no significant effect on shoot dry weight or shoot ontogeny.
- Taxon
- Pond pine
Pinus serotinae1 - Treatment
- aeration treatmente0
- Outcome
- shoot dry weight or shoot ontogenye0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“aeration treatment had no significant effect on shoot dry weight or shoot ontogeny”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Hypoxia reduced root dry weight after eight weeks regardless of phosphorus treatment.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- hypoxice0
- Outcome
- root dry weighte0
- Direction
- lowere0
- Qualifier
- after 8 weeks, regardless of the P treatmente0
- Comparator
- aerobic seedliingse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“root dry weight of hypoxic seedlings was significantly lower than that of aerobic seedliings after 8 weeks, regardless of the P treatment”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Under high phosphorus, hypoxia initially decreased root relative growth rate.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- hypoxiae0
- Outcome
- relative growth rates (RGR) of rootse0
- Direction
- decreasede0
- Qualifier
- high P treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean relative growth rates (RGR) of roots in the high P treatment initially decreased under hypoxia”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Root relative growth rate recovered by week six with adventitious root production.
- Taxon
- Pond pinePinus serotinae2
- Organ / stage
- adventitious rootse0
- Outcome
- relative growth rates (RGR) of rootse1
- Direction
- recoverede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“recovered by the sixth week with the production of adventitious roots”
e1“Mean relative growth rates (RGR) of roots”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Two weeks of hypoxia reduced carbon dioxide exchange rate by over 30% under high phosphorus.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- hypoxic growth conditionse0
- Outcome
- CERe0
- Direction
- decreasede0
- Value
- more than 30%e0
- Comparator
- aerobic counterpartse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two weeks of hypoxic growth conditions decreased CER and stomatal conductances of seedlings in the high P treatment by more than 30% relative to their aerobic counterparts”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Two weeks of hypoxia reduced stomatal conductance by over 30% under high phosphorus.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- hypoxic growth conditionse0
- Outcome
- stomatal conductancese0
- Direction
- decreasede0
- Value
- more than 30%e0
- Comparator
- aerobic counterpartse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two weeks of hypoxic growth conditions decreased CER and stomatal conductances of seedlings in the high P treatment by more than 30% relative to their aerobic counterparts”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Stomatal closure did not accompany a decrease in intracellular carbon dioxide.
- Taxon
- Pond pinePinus serotinae1
- Outcome
- intracellular CO 2e0
- Direction
- not accompanied by a decreasee0
- Comparator
- Stomatal closuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal closure was not accompanied by a decrease in intracellular CO 2”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Stomatal closure accompanied increased starch accumulation.
- Taxon
- Pond pinePinus serotinae1
- Outcome
- starch accumulatione0
- Direction
- increasee0
- Comparator
- Stomatal closuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal closure was not accompanied by a decrease in intracellular CO 2 , but was accompanied by an increase in starch accumulation”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Recovery of carbon exchange, stomatal conductance and carbohydrate metabolism coincided with root growth recovery.
- Taxon
- Pond pinePinus serotinae1
- Organ / stage
- roote0
- Outcome
- Recoveries of CER, stomatal conductance and carbohydrate metabolisme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Recoveries of CER, stomatal conductance and carbohydrate metabolism coincided with the recovery of root growth”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Low phosphorus did not significantly affect shoot or root dry weight until week six.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- Low P growth conditionse0
- Outcome
- shoot or root dry weighte0
- Direction
- did not significantly affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low P growth conditions did not significantly affect shoot or root dry weight until the sixth week of treatment”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Seedling and especially needle relative growth rates differed during the first two weeks under low phosphorus.
- Taxon
- Pond pinePinus serotinae2
- Treatment
- Low Pe1
- Outcome
- seedling RGR, particularly needle RGRe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“differences in seedling RGR, particularly needle RGR, were discernable during the first 2 weeks”
e1“Low P treatment effects on CER”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Low phosphorus effects on carbon exchange paralleled changes in needle relative growth.
- Taxon
- Pond pinePinus serotinae1
- Organ / stage
- needlee0
- Treatment
- Low Pe0
- Outcome
- CERe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low P treatment effects on CER paralleled changes in needle RGR”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Needle relative growth was more affected than carbon exchange under low phosphorus.
- Taxon
- Pond pinePinus serotinae2
- Treatment
- Low Pe1
- Outcome
- needle RGRe0
- Comparator
- CERe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“needle RGR more affected than CER”
e1“Low P treatment effects on CER”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
After six weeks, low phosphorus reduced carbon exchange rate by 15% in aerobic seedlings.
- Taxon
- Pond pinePinus serotinae1
- Treatment
- low P treatmente0
- Outcome
- CERe0
- Direction
- lowere0
- Value
- 15%e0
- Comparator
- high P treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CER of aerobically grown seedlings in the low P treatment were only 15% lower than CER of seedlings in the high P treatment”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
After six weeks, low phosphorus reduced needle relative growth by 31%.
- Taxon
- Pond pinePinus serotinae2
- Treatment
- low P treatmente1
- Outcome
- needle RGRe0
- Direction
- reductione0
- Value
- 31%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“31% and 75% reduction in needle RGR and Pi concentrations, respectively”
e1“low P treatment”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
After six weeks, low phosphorus reduced needle inorganic phosphorus by 75%.
- Taxon
- Pond pinePinus serotinae2
- Treatment
- low P treatmente1
- Outcome
- Pi concentrationse0
- Direction
- reductione0
- Value
- 75%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“31% and 75% reduction in needle RGR and Pi concentrations, respectively”
e1“low P treatment”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Recently expanded needles had increased starch concentrations, probably from diminished growth.
- Taxon
- Pond pinePinus serotinae1
- Organ / stage
- recently expanded needlese0
- Outcome
- Increased starch concentrationse0
- Qualifier
- diminished growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased starch concentrations of recently expanded needles at this time were probably a result of diminished growth”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
Low phosphorus inhibited shoot growth, especially needle expansion and emergence of new fascicular needles.
- Taxon
- Pond pinePinus serotinae1
- Organ / stage
- new fascicular needlese0
- Treatment
- low P supplye0
- Outcome
- shoot growthe0
- Direction
- inhibitorye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inhibitory effect of a low P supply on shoot growth, more specifically on needle expansion and emergence of new fascicular needles”
e1“Pond pine ( Pinus serotina Michx.) seedlings”
Claim · model-written summary
The authors infer inhibited growth limited net carbon fixed per plant more than direct effects on carbon exchange.
- Taxon
- Pond pinePinus serotinae2
- Treatment
- low P supplye1
- Outcome
- net carbon fixed per plante0
- Qualifier
- shoot growthe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“probably limited net carbon fixed per plant more than any direct effect of low P on CER per se”
e1“inhibitory effect of a low P supply on shoot growth”
e2“Pond pine ( Pinus serotina Michx.) seedlings”
The same questions in other papers
phosphorus · growth · Pinus serotina (pond pine)Positive and negative results
1 in the opposite direction
- negative
flooding · growth · Pinus serotina (pond pine)Results agree
2 papers in the same direction as this paper
- negative
- 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.