Abstract
Nitrogen deficiency limits crop performance under elevated CO2 (eCO2), depending on the ability of plant N uptake. However, the dynamics and redistribution of N2 fixation, and fertilizer and soil N use in legumes under eCO2 have been little studied. Such an investigation is essential to improve the adaptability of legumes to climate change. We took advantage of genotype-specific responses of soybean to increased CO2 to test which N-uptake phenotypes are most strongly related to enhanced yield. Eight soybean cultivars were grown in open-top chambers with either 390 ppm (aCO2) or 550 ppm CO2 (eCO2). The plants were supplied with 100 mg N kg-1 soil as 15N-labelled calcium nitrate, and harvested at the initial seed-filling (R5) and full-mature (R8) stages. Increased yield in response to eCO2 correlated highly (r=0.95) with an increase in symbiotically fixed N during the R5 to R8 stage. In contrast, eCO2 only led to small increases in the uptake of fertilizer-derived and soil-derived N during R5 to R8, and these increases did not correlate with enhanced yield. Elevated CO2 also decreased the proportion of seed N redistributed from shoot to seeds, and this decrease strongly correlated with increased yield. Moreover, the total N uptake was associated with increases in fixed-N per nodule in response to eCO2, but not with changes in nodule biomass, nodule density or root length.
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Claims 8
Claim · model-written summary
Yield response to elevated CO2 correlated strongly with increased symbiotically fixed N between R5 and R8.
- Taxon
- Soybean
Glycine maxt0 - Organ / stage
- R5 to R8 stagee0
- Treatment
- eCO2e0
- Outcome
- Increased yielde0
- Direction
- Increasede0
- Value
- r=0.95e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“Increased yield in response to eCO2 correlated highly (r=0.95) with an increase in symbiotically fixed N during the R5 to R8 stage.”
Claim · model-written summary
Elevated CO2 caused small increases in fertilizer-derived N uptake from R5 to R8.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- R5 to R8e0
- Treatment
- eCO2e0
- Outcome
- uptake of fertilizer-derivede0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“eCO2 only led to small increases in the uptake of fertilizer-derived and soil-derived N during R5 to R8”
Claim · model-written summary
Elevated CO2 caused small increases in soil-derived N uptake from R5 to R8.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- R5 to R8e0
- Treatment
- eCO2e0
- Outcome
- soil-derived Ne0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“eCO2 only led to small increases in the uptake of fertilizer-derived and soil-derived N during R5 to R8”
Claim · model-written summary
Increases in fertilizer-derived and soil-derived N uptake did not correlate with enhanced yield.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- these increasese0
- Outcome
- enhanced yielde0
- Direction
- did not correlatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“these increases did not correlate with enhanced yield”
Claim · model-written summary
Elevated CO2 reduced the proportion of seed N redistributed from shoots to seeds.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- Elevated CO2e0
- Outcome
- proportion of seed N redistributed from shoot to seedse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“Elevated CO2 also decreased the proportion of seed N redistributed from shoot to seeds”
Claim · model-written summary
The decrease in redistributed seed N correlated strongly with increased yield.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- this decreasee0
- Outcome
- increased yielde0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“this decrease strongly correlated with increased yield”
Claim · model-written summary
Total N uptake was associated with increased fixed N per nodule under elevated CO2.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- eCO2e0
- Outcome
- total N uptakee0
- Qualifier
- increases in fixed-N per nodulee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“the total N uptake was associated with increases in fixed-N per nodule in response to eCO2”
Claim · model-written summary
Total N uptake was not associated with changes in nodule biomass, density or root length.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- nodulee0
- Outcome
- changes in nodule biomass, nodule density or root lengthe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“but not with changes in nodule biomass, nodule density or root length”
The same questions in other papers
co2 · nutrient: content · Glycine max (soybean)Positive and negative results
11 papers in the same direction as this paper · 14 in the opposite direction · 1 reporting no difference from an alternative
- negative
- negative
- positive
23 papers more in this group
See all 27 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.