Abstract
The rate of N2 fixation by a leguminous plant is a product of the activity of individual nodules and the number of nodules. Initiation of new nodules and N2 fixation per nodule are highly sensitive to environmental conditions. However, the effects of global environmental change on nodulation in the field are largely unknown. It is also unclear whether legumes regulate nodulation in response to environment solely by varying root production or also by varying nodule density per unit of root length. This study utilised minirhizotron imaging as a novel in situ method for assessing the number, size and distribution of nodules in field-grown soybean (Glycine max (L.) Merr.) exposed to elevated atmospheric CO2 ([CO2]) and reduced precipitation. We found that nodule numbers were 134-229% greater in soybeans grown at elevated [CO2] in combination with reduced precipitation, and this response was driven by greater nodule density per unit of root length. The benefits of additional nodules were probably offset by an unfavourable distribution of nodules in shallow, dry soil in reduced precipitation treatment under elevated [CO2] but not ambient [CO2]. In fact, significant decreases in seed and leaf nitrogen concentration also occurred only in elevated [CO2] with reduced precipitation. This study demonstrates the potential of minirhizotron imaging to reveal previously uncharacterised changes in nodule production and distribution in response to global environmental change.
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Claims 5
Claim · model-written summary
Elevated CO2 combined with reduced precipitation increased soybean nodule numbers by 134-229%.
- Taxon
- soybeans
Glycine maxe0 - Treatment
- elevated [CO2] in combination with reduced precipitatione0
- Outcome
- nodule numberse0
- Direction
- greatere0
- Value
- 134-229%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We found that nodule numbers were 134-229% greater in soybeans grown at elevated [CO2] in combination with reduced precipitation, and this response was driven by greater nodule density per unit of root length.”
Claim · model-written summary
Greater nodule density per root length drove the soybean nodule-number response.
- Taxon
- soybeansGlycine maxe0
- Outcome
- nodule numberse0
- Direction
- greatere0
- Qualifier
- greater nodule density per unit of root lengthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We found that nodule numbers were 134-229% greater in soybeans grown at elevated [CO2] in combination with reduced precipitation, and this response was driven by greater nodule density per unit of root length.”
Claim · model-written summary
Shallow, dry-soil nodule distribution probably offset additional nodule benefits under reduced precipitation with elevated, but not ambient, CO2.
- Taxon
- soybeanGlycine maxt0
- Treatment
- reduced precipitation treatment under elevated [CO2]e0
- Outcome
- benefits of additional nodulese0
- Qualifier
- probably offset by an unfavourable distribution of nodules in shallow, dry soile0
- Comparator
- ambient [CO2]e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The benefits of additional nodules were probably offset by an unfavourable distribution of nodules in shallow, dry soil in reduced precipitation treatment under elevated [CO2] but not ambient [CO2].”
t0“soybean”
Claim · model-written summary
Seed and leaf nitrogen concentrations decreased significantly only under elevated CO2 with reduced precipitation.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated [CO2] with reduced precipitatione0
- Outcome
- seed and leaf nitrogen concentratione0
- Direction
- decreasese0
- Qualifier
- onlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In fact, significant decreases in seed and leaf nitrogen concentration also occurred only in elevated [CO2] with reduced precipitation.”
t0“soybean”
Claim · model-written summary
Minirhizotron imaging demonstrated potential to reveal changes in soybean nodule production and distribution under global environmental change.
- Taxon
- soybeanGlycine maxt0
- Outcome
- reveal previously uncharacterised changes in nodule production and distributione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This study demonstrates the potential of minirhizotron imaging to reveal previously uncharacterised changes in nodule production and distribution in response to global environmental change.”
t0“soybean”
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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.