Abstract
Understanding the role of S in soybean [ Glycine max (L.) Merr.] growth is important because a deficiency of the S‐containing amino acids methionine and cysteine limits the nutritional value of soybean protein. As part of a broader study of S uptake and use, our objective was to quantify the effect of S availability on photosynthetic characteristics of soybean. Kenwood soybean was grown in a 3:1 mixture of Ida silt loam [fine‐silty, mixed (calcareous), mesic Typic Udorthent] and acid washed sand with varying amounts of S added as gypsum (CaSO 4 ) in two greenhouse trials. Single‐leaf CO 2 ‐exchange rate (CER), quantum efficiency, dark respiration, leaf S, leaf N, and Rubisco content were determined. There appeared to be a critical level of 35 mg S per kg mixture (about 85 mg S per plant) below which specific leaf S (mg m −2 leaf area) declined linearly with decreases in soil S availability. On average, the most S deficient plants had 70% lower CER, 42% less quantum efficiency, and 50% decline in dark respiration relative to plants receiving adequate S. Total leaf N and Rubisco content were linearly related to leaf S levels, and declined on average 62, and 95%, respectively, as S declined from approximately 120 to 40 mg S m −2 leaf area. There was a linear relation between CER and Rubisco content; however, the amount of nonstructural carbohydrates per unit leaf N increased two‐fold under S deficiency, suggesting that limitations on sink strength were greater than those on source capacity. Carbon dioxide exchange rate was linearly related to leaf S content at all sample dates, with a mean relation of 216 (μmol CO 2 g −1 S s −1 . The Rubisco fraction declined linearly from nearly 50 to <10% of soluble protein, as leaf soluble protein content declined under S deficiency. We postulate that the decline in the Rubisco fraction may be a function of increased relative importance of housekeeping enzymes for survival as protein levels decline, and/or down‐regulation of Rubisco synthesis in response to a build up of carbohydrates in the source leaves under S deficiency.
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Claims 11
Claim · model-written summary
Most S deficient soybean plants had 70% lower CO2 exchange rate than plants with adequate S
- Taxon
- Soybean
Glycine maxt0 - Treatment
- most S deficiente1
- Outcome
- CERe1
- Direction
- lowere1
- Value
- 70%e1
- Comparator
- plants receiving adequate Se1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e1“On average, the most S deficient plants had 70% lower CER, 42% less quantum efficiency, and 50% decline in dark respiration relative to plants receiving adequate S”
Claim · model-written summary
Most S deficient soybean plants had 42% less quantum efficiency than plants with adequate S
- Taxon
- SoybeanGlycine maxt0
- Treatment
- most S deficiente1
- Outcome
- quantum efficiencye1
- Direction
- lesse1
- Value
- 42%e1
- Comparator
- plants receiving adequate Se1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e1“On average, the most S deficient plants had 70% lower CER, 42% less quantum efficiency, and 50% decline in dark respiration relative to plants receiving adequate S”
Claim · model-written summary
Most S deficient soybean plants had 50% lower dark respiration than plants with adequate S
- Taxon
- SoybeanGlycine maxt0
- Treatment
- most S deficiente1
- Outcome
- dark respiratione1
- Direction
- declinee1
- Value
- 50%e1
- Comparator
- plants receiving adequate Se1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e1“On average, the most S deficient plants had 70% lower CER, 42% less quantum efficiency, and 50% decline in dark respiration relative to plants receiving adequate S”
Claim · model-written summary
Total leaf N declined with decreasing leaf S levels
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e2“Total leaf N and Rubisco content were linearly related to leaf S levels, and declined on average 62, and 95%, respectively, as S declined from approximately 120 to 40 mg S m −2 leaf area”
Claim · model-written summary
Rubisco content declined with decreasing leaf S levels
- Taxon
- SoybeanGlycine maxt0
- Treatment
- leaf S levelse2
- Outcome
- Rubisco contente2
- Direction
- declinede2
- Value
- 95%e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e2“Total leaf N and Rubisco content were linearly related to leaf S levels, and declined on average 62, and 95%, respectively, as S declined from approximately 120 to 40 mg S m −2 leaf area”
Claim · model-written summary
CO2 exchange rate was linearly related to Rubisco content
- Taxon
- SoybeanGlycine maxt0
- Gene
- Rubiscoe3
- Outcome
- CERe3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e3“There was a linear relation between CER and Rubisco content”
Claim · model-written summary
The amount of nonstructural carbohydrates per unit leaf N increased under S deficiency
- Taxon
- SoybeanGlycine maxt0
- Treatment
- S deficiencye5
- Outcome
- nonstructural carbohydrates per unit leaf Ne4
- Direction
- increasede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e4“the amount of nonstructural carbohydrates per unit leaf N increased”
e5“under S deficiency, suggesting that limitations on sink strength”
Claim · model-written summary
The Rubisco fraction of soluble protein declined linearly from nearly 50 to below 10% as S deficiency progressed
- Taxon
- SoybeanGlycine maxt0
- Gene
- Rubiscoe6
- Outcome
- Rubisco fractione6
- Direction
- declinede6
- Value
- from nearly 50 to <10%e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e6“The Rubisco fraction declined linearly from nearly 50 to <10% of soluble protein”
Claim · model-written summary
Carbon dioxide exchange rate was linearly related to leaf S content at all sample dates
- Taxon
- SoybeanGlycine maxt0
- Treatment
- leaf S contente7
- Outcome
- Carbon dioxide exchange ratee7
- Value
- 216e7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e7“Carbon dioxide exchange rate was linearly related to leaf S content at all sample dates, with a mean relation of 216”
Claim · model-written summary
Specific leaf S declined linearly below a critical level of 35 mg S per kg mixture as soil S availability decreased
- Taxon
- SoybeanGlycine maxt0
- Treatment
- soil S availabilitye0
- Outcome
- specific leaf Se0
- Direction
- declinede0
- Value
- 35 mg S per kg mixturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e0“There appeared to be a critical level of 35 mg S per kg mixture (about 85 mg S per plant) below which specific leaf S (mg m −2 leaf area) declined linearly with decreases in soil S availability”
Claim · model-written summary
The decline in the Rubisco fraction may reflect increased relative importance of housekeeping enzymes for survival
- Taxon
- SoybeanGlycine maxt0
- Outcome
- decline in the Rubisco fractione1
- Qualifier
- increased relative importance of housekeeping enzymes for survivale1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Photosynthetic Rate of Soybean”
e1“We postulate that the decline in the Rubisco fraction may be a function of increased relative importance of housekeeping enzymes for survival as protein levels decline”
The same questions in other papers
sulfur atom · physiology: photosynthesis · Glycine max (soybean)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
This paper is about lacking the nutrient, so it counts the other way round here.
- negative
- positive
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.