Abstract
Abstract Over time, the relative effects of elevated [CO 2 ] on the aboveground photosynthesis, growth and development of rice ( Oryza sativa L.) are likely to be changed with increasing duration of CO 2 exposure, but the resultant effects on rice belowground responses remain to be evaluated. To investigate the impacts of elevated [CO 2 ] on seasonal changes in root growth, morphology and physiology of rice, a free‐air CO 2 enrichment (FACE) experiment was performed at Wuxi, Jiangsu, China, in 2002–2003. A japonica cultivar with large panicle was exposed to two [CO 2 ] (ambient [CO 2 ], 370 μmol mol −1 ; elevated [CO 2 ], 570 μmol mol −1 ) at three levels of nitrogen (N): low (LN, 15 g N m −2 ), medium (MN, 25 g N m −2 ) and high N (HN, 35 g N m −2 ). Elevated [CO 2 ] increased cumulative root volume, root dry weight, adventitious root length and adventitious root number at all developmental stages by 25–71%, which was mainly associated with increased root growth rate during early growth period (EGP) and lower rate of root senescence during late growth period (LGP), while a slight inhibition of root growth rate occurred during middle growth period (MGP). For individual adventitious roots, elevated [CO 2 ] increased average length, volume, diameter and dry weight early in the season, but the effects gradually disappeared in subsequent stages. Total surface area and active adsorption area per unit root dry weight reached their maxima 10 days earlier in FACE vs. ambient plants, but both of them together with root oxidation ability per unit root dry weight declined with elevated [CO 2 ] during MGP and LGP, the decline being larger during MGP than LGP. The CO 2 ‐induced decreases in specific root activities during MGP and LGP were associated with a larger amount of root accumulation during EGP and lower N concentration and higher C/N ratio in roots during MGP and LGP in FACE vs. ambient plants. The results suggest that most of the CO 2 ‐induced increases in shoot growth of rice are similarly associated with increased root growth.
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Claims 10
Claim · model-written summary
Elevated CO2 increased cumulative root volume, dry weight, adventitious root length and number at all stages by 25–71%.
- Taxon
- rice
Oryza sativae1 - Treatment
- Elevated [CO 2 ]e0
- Outcome
- cumulative root volume, root dry weight, adventitious root length and adventitious root numbere0
- Direction
- increasede0
- Value
- 25–71%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated [CO 2 ] increased cumulative root volume, root dry weight, adventitious root length and adventitious root number at all developmental stages by 25–71%”
e1“rice ( Oryza sativa L.)”
Claim · model-written summary
Elevated CO2 increased early root growth rate.
- Taxon
- riceOryza sativae1
- Organ / stage
- early growth period (EGP)e0
- Treatment
- Elevated [CO 2 ]e2
- Outcome
- root growth ratee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased root growth rate during early growth period (EGP)”
e1“rice ( Oryza sativa L.)”
e2“Elevated [CO 2 ] increased cumulative root volume”
Claim · model-written summary
Elevated CO2 lowered late root senescence rate.
- Taxon
- riceOryza sativae1
- Organ / stage
- late growth period (LGP)e0
- Treatment
- Elevated [CO 2 ]e2
- Outcome
- root senescencee0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower rate of root senescence during late growth period (LGP)”
e1“rice ( Oryza sativa L.)”
e2“Elevated [CO 2 ] increased cumulative root volume”
Claim · model-written summary
Elevated CO2 slightly inhibited root growth rate during the middle growth period.
- Taxon
- riceOryza sativae1
- Organ / stage
- middle growth period (MGP)e0
- Treatment
- Elevated [CO 2 ]e2
- Outcome
- root growth ratee0
- Direction
- inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a slight inhibition of root growth rate occurred during middle growth period (MGP)”
e1“rice ( Oryza sativa L.)”
e2“Elevated [CO 2 ] increased cumulative root volume”
Claim · model-written summary
Elevated CO2 increased adventitious root length, volume, diameter and dry weight early in the season; the effects faded later.
- Taxon
- riceOryza sativae1
- Treatment
- elevated [CO 2 ]e0
- Outcome
- average length, volume, diameter and dry weighte0
- Direction
- increasede0
- Qualifier
- the effects gradually disappeared in subsequent stagese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO 2 ] increased average length, volume, diameter and dry weight early in the season, but the effects gradually disappeared in subsequent stages”
e1“rice ( Oryza sativa L.)”
Claim · model-written summary
Total surface and active adsorption areas per unit root dry weight peaked ten days earlier under FACE than ambient conditions.
- Taxon
- riceOryza sativae1
- Treatment
- FACEe0
- Outcome
- Total surface area and active adsorption area per unit root dry weighte0
- Direction
- earliere0
- Value
- 10 dayse0
- Comparator
- ambient plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total surface area and active adsorption area per unit root dry weight reached their maxima 10 days earlier in FACE vs. ambient plants”
e1“rice ( Oryza sativa L.)”
Claim · model-written summary
Elevated CO2 reduced root surface area, active adsorption area and oxidation ability per unit dry weight in middle and late growth, more strongly in middle growth.
- Taxon
- riceOryza sativae2
- Treatment
- elevated [CO 2 ]e0
- Outcome
- Total surface area and active adsorption area per unit root dry weighte1
- Direction
- declinede0
- Qualifier
- the decline being larger during MGP than LGPe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both of them together with root oxidation ability per unit root dry weight declined with elevated [CO 2 ] during MGP and LGP, the decline being larger during MGP than LGP”
e1“Total surface area and active adsorption area per unit root dry weight”
e2“rice ( Oryza sativa L.)”
Claim · model-written summary
FACE roots had lower N concentration and higher C/N ratio in middle and late growth.
- Taxon
- riceOryza sativae1
- Outcome
- N concentratione0
- Direction
- lowere0
- Comparator
- ambient plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower N concentration and higher C/N ratio in roots during MGP and LGP in FACE vs. ambient plants”
e1“rice ( Oryza sativa L.)”
Claim · model-written summary
FACE roots had a higher C/N ratio in middle and late growth than ambient roots.
- Taxon
- riceOryza sativae1
- Outcome
- C/N ratioe0
- Direction
- highere0
- Comparator
- ambient plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher C/N ratio in roots during MGP and LGP in FACE vs. ambient plants”
e1“rice ( Oryza sativa L.)”
Claim · model-written summary
Authors infer that increased rice shoot growth under CO2 enrichment is associated with increased root growth.
- Taxon
- riceOryza sativae0
- Organ / stage
- roote0
- Outcome
- shoot growthe0
- Direction
- increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most of the CO 2 ‐induced increases in shoot growth of rice are similarly associated with increased root growth”
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See all 124 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.