Abstract
Calcium (Ca) is pivotal for symbiotic nitrogen fixation (SNF) and the overall growth and development of legumes. However, the mechanisms by which varying Ca supply levels coordinate the homeostasis between nodular N fixation and nitrogen (N) metabolism remain poorly understood. This study conducted a two-year sand culture experiment to investigate the effects of low (Ca0.1), optimal (Ca1), and high (Ca10) calcium regimes on soybean (Glycine max L.). Optimal Ca supply (1 mmol·L−1, Ca1) significantly promoted plant growth and increased grain yield by 54.5–91.0% in 2024 and 55.3–74.7% in 2025 compared to other regimes. It maximized nitrogenase activity (SNA and ARA)—with ARA being 1.63–2.51 fold higher than in stressed plants in 2025—and significantly upregulated N-metabolism enzymes (GS, GOGAT, GLS, and L-ASNase) in both leaves and nodules. Furthermore, amino acid profiling substantiated that optimal Ca improved N utilization efficiency by preventing the atypical buildup of free amino acids (FAAs) observed under Ca-stress conditions. In summary, an optimal Ca supply maximizes soybean productivity by synergistically enhancing biological nitrogen fixation capacity and N-use efficiency. This coordination maintains carbon–nitrogen (C/N) homeostasis and improves key yield components, providing a theoretical framework for refined Ca fertilization management in soybean production.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by-nc-nd. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 8
Claim · model-written summary
Optimal calcium significantly promoted soybean growth.
- Taxon
- soybean
Glycine maxe1 - Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e0
- Outcome
- plant growthe0
- Direction
- promotede0
- Comparator
- other regimese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Optimal Ca supply (1 mmol·L−1, Ca1) significantly promoted plant growth and increased grain yield by 54.5–91.0% in 2024 and 55.3–74.7% in 2025 compared to other regimes”
e1“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium raised grain yield 54.5–91.0% in 2024.
- Taxon
- soybeanGlycine maxe2
- Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e1
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 54.5–91.0%e0
- Qualifier
- 2024e0
- Comparator
- other regimese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased grain yield by 54.5–91.0% in 2024 and 55.3–74.7% in 2025 compared to other regimes”
e1“Optimal Ca supply (1 mmol·L−1, Ca1)”
e2“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium raised grain yield 55.3–74.7% in 2025.
- Taxon
- soybeanGlycine maxe2
- Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e1
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 55.3–74.7%e0
- Qualifier
- 2025e0
- Comparator
- other regimese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased grain yield by 54.5–91.0% in 2024 and 55.3–74.7% in 2025 compared to other regimes”
e1“Optimal Ca supply (1 mmol·L−1, Ca1)”
e2“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium maximized nitrogenase activity.
- Taxon
- soybeanGlycine maxe2
- Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e1
- Outcome
- nitrogenase activity (SNA and ARA)e0
- Direction
- maximizede0
- Comparator
- stressed plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It maximized nitrogenase activity (SNA and ARA)—with ARA being 1.63–2.51 fold higher than in stressed plants in 2025”
e1“Optimal Ca supply (1 mmol·L−1, Ca1)”
e2“soybean (Glycine max L.)”
Claim · model-written summary
ARA was 1.63–2.51 fold higher in 2025 than in stressed plants.
- Taxon
- soybeanGlycine maxe2
- Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e1
- Outcome
- ARAe0
- Direction
- highere0
- Value
- 1.63–2.51 folde0
- Qualifier
- 2025e0
- Comparator
- stressed plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ARA being 1.63–2.51 fold higher than in stressed plants in 2025”
e1“Optimal Ca supply (1 mmol·L−1, Ca1)”
e2“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium upregulated four nitrogen metabolism enzymes in leaves and nodules.
- Taxon
- soybeanGlycine maxe2
- Organ / stage
- leaves and nodulese0
- Treatment
- Optimal Ca supply (1 mmol·L−1, Ca1)e1
- Outcome
- N-metabolism enzymese0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significantly upregulated N-metabolism enzymes (GS, GOGAT, GLS, and L-ASNase) in both leaves and nodules”
e1“Optimal Ca supply (1 mmol·L−1, Ca1)”
e2“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium prevented the atypical buildup of free amino acids seen under calcium stress.
- Taxon
- soybeanGlycine maxe1
- Treatment
- optimal Cae0
- Outcome
- buildup of free amino acids (FAAs)e0
- Direction
- preventinge0
- Comparator
- Ca-stress conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“optimal Ca improved N utilization efficiency by preventing the atypical buildup of free amino acids (FAAs) observed under Ca-stress conditions”
e1“soybean (Glycine max L.)”
Claim · model-written summary
Optimal calcium improved nitrogen utilization efficiency.
- Taxon
- soybeanGlycine maxe1
- Treatment
- optimal Cae0
- Outcome
- N utilization efficiencye0
- Direction
- improvede0
- Comparator
- Ca-stress conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“optimal Ca improved N utilization efficiency by preventing the atypical buildup of free amino acids (FAAs) observed under Ca-stress conditions”
e1“soybean (Glycine max L.)”
The same questions in other papers
calcium atom · growth · Glycine max (soybean)Results differ
25 papers in the same direction as this paper · 9 in the opposite direction
- no effect
- no effect
- no effect
31 papers more in this group
See all 35 papers →calcium atom · physiology: enzyme activity · Glycine max (soybean)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
calcium atom · molecular: metabolites · Glycine max (soybean)Positive and negative results
10 papers in the same direction as this paper · 5 in the opposite direction
- negative
- no effect
- no effect
12 papers more in this group
See all 16 papers →calcium atom · yield · Glycine max (soybean)Positive and negative results
11 papers in the same direction as this paper · 8 in the opposite direction
- no effect
- negative
- no effect
16 papers more in this group
See all 20 papers →calcium atom · symbiosis · Glycine max (soybean)Results agree
4 papers in the same direction as this paper
- positive
- positive
- positive
1 paper more in this group
See all 5 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.