Abstract
Abstract Dinitrogen fixation in soybean [ Glycine max (L.) Merr.] is especially sensitive to soil drying, and this trait can have important negative affects on yield. An exception to this general response has been the identification of ‘Jackson’ soybean as drought tolerant for N 2 fixation. The objectives of this research were to examine the response in additional soybean cultivars of N 2 fixation to soil drying under field conditions, and to determine if there is any link between the drought sensitivity among cultivars and the ureide levels in the plants. Two field experiments were conducted to further examine the genetic variation in the sensitivity of soybean cultivars for biomass and N accumulation rates in response to soil drying. Substantial variation among soybean lines was found, and the drought‐tolerance trait was demonstrated again in Jackson. Differences between cultivars in the response of N accumulation to drought stress were associated with differences in petiole ureide concentration found in well‐watered plants. An experiment was conducted in the greenhouse with eight soybean cultivars grown in pots and exposed to drought by soil dehydration over a 2‐wk period. Differences among cultivars in the sensitivity of N 2 ‐fixation rates to soil drying found from measurements of acetylene reduction activity (ARA) in the greenhouse correlated with differences in N accumulation in the field ( r 2 = 0.86). The tolerance of N 2 fixation to drought stress was associated ( r 2 = 0.84) with maximum ARA in response to changes in O 2 concentration around nodules. Among the eight cultivars, there was a significant negative correlation ( r 2 = 0.73) between the drought tolerance of N 2 fixation and ureide concentration in the xylem sap. Ureide levels might be an efficient way to screen large numbers of genotypes for N 2 ‐fixation drought tolerance.
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Claims 7
Claim · model-written summary
Soybean lines varied substantially in drought responses of biomass and nitrogen accumulation.
- Taxon
- soybean
Glycine maxe0 - Outcome
- variation among soybean linese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Substantial variation among soybean lines was found”
Claim · model-written summary
Jackson again showed drought tolerance.
- Taxon
- soybeanGlycine maxt0
- Material
- Jacksone0
- Outcome
- drought‐tolerance traite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the drought‐tolerance trait was demonstrated again in Jackson”
t0“Soybean”
Claim · model-written summary
Cultivar differences in nitrogen accumulation response to drought were associated with petiole ureides in well-watered plants.
- Taxon
- soybeanGlycine maxt0
- Compound
- petiole ureide concentratione0
- Outcome
- response of N accumulation to drought stresse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Differences between cultivars in the response of N accumulation to drought stress were associated with differences in petiole ureide concentration found in well‐watered plants”
t0“Soybean”
Claim · model-written summary
Greenhouse sensitivity of nitrogen fixation to drying correlated with field nitrogen accumulation (r² = 0.86).
- Taxon
- soybeanGlycine maxt0
- Outcome
- sensitivity of N 2 ‐fixation rates to soil dryinge0
- Value
- r 2 = 0.86e0
- Comparator
- N accumulation in the fielde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Differences among cultivars in the sensitivity of N 2 ‐fixation rates to soil drying found from measurements of acetylene reduction activity (ARA) in the greenhouse correlated with differences in N accumulation in the field ( r 2 = 0.86)”
t0“Soybean”
Claim · model-written summary
Drought tolerance of nitrogen fixation was associated with maximum ARA response to oxygen around nodules (r² = 0.84).
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- nodulese0
- Compound
- O 2e0
- Outcome
- tolerance of N 2 fixation to drought stresse0
- Value
- r 2 = 0.84e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The tolerance of N 2 fixation to drought stress was associated ( r 2 = 0.84) with maximum ARA in response to changes in O 2 concentration around nodules”
t0“Soybean”
Claim · model-written summary
Fixation drought tolerance correlated negatively with xylem sap ureides among eight cultivars (r² = 0.73).
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- xylem sape0
- Compound
- ureide concentratione0
- Outcome
- drought tolerance of N 2 fixatione0
- Direction
- negative correlatione0
- Value
- r 2 = 0.73e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Among the eight cultivars, there was a significant negative correlation ( r 2 = 0.73) between the drought tolerance of N 2 fixation and ureide concentration in the xylem sap”
t0“Soybean”
Claim · model-written summary
Ureide levels may efficiently screen genotypes for fixation drought tolerance.
- Taxon
- soybeanGlycine maxt0
- Outcome
- screen large numbers of genotypes for N 2 ‐fixation drought tolerancee0
- Qualifier
- might be an efficient waye0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ureide levels might be an efficient way to screen large numbers of genotypes for N 2 ‐fixation drought tolerance”
t0“Soybean”