Abstract
Abstract Foliar fertilization (FF) was reported to increase seed yields of soybean [ Glycine max (L.) Merr.] in field experiments in Iowa, but yield increases were not consistent. The researchers hypothesized that FF should minimize nutrient depletion from leaves during seed development, and thereby delay the resulting decrease in leaf photosynthesis. To test this hypothesis, we conducted a field experiment in 1976 to determine the effect of FF on leaf element concentrations, gross leaf photosynthesis (Pg), and soybean seed yield. Five weekly foliar sprays were applied during the seed‐filling period of ‘Bragg’ soybean grown at Gainesville, Florida on Kendrick loamy sand (loamy, siliceous, hyperthermic grossarenic paleudult). At weekly intervals, we sampled upper leaves and total canopy leaves and analyzed them for N, P, and K, and measured Pg of upper leaves in mid‐day sun with a 14 CO 2 gas flow technique. Foliar applications of N, P, K, and S increased the N, P, and K concentration of total canopy leaves from 3.28, 0.24, and 0.92% to 3.48, 0.29, and 1.32%, respectively. FF significantly increased upper leaf Pg only at two late sample dates when seed growth was nearly complete and most leaves had already senesced and dropped. Even though nutrient concentrations were increased, FF did not significantly affect yields nor did it extend Pg duration or delay maturity. Treated soybeans yielded 3617 kg/ha compared to 3825 kg/ha for control soybeans. Leaf Pg and concentrations of N and P in leaves progressively decreased during seed‐filling until maturity but K did not decline. Leaf Pg was positively correlated with N (r = 0.87) and approached zero at approximately 1.75% N, a concentration similar to that of senesced, recently abscised leaves. Maximum Pg was predicted at 4.6 to 6.0% leaf N. Leaf Pg and percent P were also positively correlated. The relationship of Pg to leaf N during N removal from leaves can potentially be used to model photosynthetic decline during seed‐filling.
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Claims 15
Claim · model-written summary
Foliar fertilization increased canopy leaf N concentration from 3.28 to 3.48%.
- Taxon
- Soybeans
Glycine maxt0 - Treatment
- Foliar applications of N, P, K, and Se0
- Outcome
- N, P, and K concentratione0
- Direction
- increasede0
- Value
- 3.48e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar applications of N, P, K, and S increased the N, P, and K concentration of total canopy leaves from 3.28, 0.24, and 0.92% to 3.48, 0.29, and 1.32%, respectively.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization increased canopy leaf P concentration from 0.24 to 0.29%.
- Taxon
- SoybeansGlycine maxt0
- Treatment
- Foliar applications of N, P, K, and Se0
- Outcome
- Pe0
- Direction
- increasede0
- Value
- 0.29e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar applications of N, P, K, and S increased the N, P, and K concentration of total canopy leaves from 3.28, 0.24, and 0.92% to 3.48, 0.29, and 1.32%, respectively.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization increased canopy leaf K concentration from 0.92 to 1.32%.
- Taxon
- SoybeansGlycine maxt0
- Treatment
- Foliar applications of N, P, K, and Se0
- Outcome
- K concentratione0
- Direction
- increasede0
- Value
- 1.32%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar applications of N, P, K, and S increased the N, P, and K concentration of total canopy leaves from 3.28, 0.24, and 0.92% to 3.48, 0.29, and 1.32%, respectively.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization significantly increased upper leaf photosynthesis only on two late sample dates.
- Taxon
- soybeanGlycine maxt0
- Treatment
- FFe0
- Outcome
- upper leaf Pge0
- Direction
- increasede0
- Qualifier
- two late sample datese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FF significantly increased upper leaf Pg only at two late sample dates when seed growth was nearly complete and most leaves had already senesced and dropped.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization did not significantly affect seed yield.
- Taxon
- soybeanGlycine maxt0
- Treatment
- FFe0
- Outcome
- yieldse0
- Direction
- did not significantly affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Even though nutrient concentrations were increased, FF did not significantly affect yields nor did it extend Pg duration or delay maturity.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization did not extend photosynthesis duration.
- Taxon
- soybeanGlycine maxt0
- Treatment
- FFe0
- Outcome
- Pg duratione0
- Direction
- nor did it extende0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Even though nutrient concentrations were increased, FF did not significantly affect yields nor did it extend Pg duration or delay maturity.”
t0“Soybeans”
Claim · model-written summary
Foliar fertilization did not delay maturity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- FFe0
- Outcome
- maturitye0
- Direction
- delaye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Even though nutrient concentrations were increased, FF did not significantly affect yields nor did it extend Pg duration or delay maturity.”
t0“Soybeans”
Claim · model-written summary
Treated soybean yielded 3617 kg/ha versus 3825 kg/ha in controls.
- Taxon
- soybeansGlycine maxe0
- Outcome
- yieldede0
- Value
- 3617 kg/hae0
- Qualifier
- 3825 kg/hae0
- Comparator
- control soybeanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treated soybeans yielded 3617 kg/ha compared to 3825 kg/ha for control soybeans.”
Claim · model-written summary
Leaf photosynthesis and leaf N and P concentrations decreased through seed filling to maturity.
- Taxon
- soybeanGlycine maxt0
- Outcome
- Leaf Pg and concentrations of N and P in leavese0
- Direction
- progressively decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf Pg and concentrations of N and P in leaves progressively decreased during seed‐filling until maturity but K did not decline.”
t0“Soybeans”
Claim · model-written summary
Leaf K did not decline during seed filling.
- Taxon
- soybeanGlycine maxt0
- Outcome
- Ke0
- Direction
- did not declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf Pg and concentrations of N and P in leaves progressively decreased during seed‐filling until maturity but K did not decline.”
t0“Soybeans”
Claim · model-written summary
Leaf photosynthesis correlated positively with leaf N.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- leafe0
- Outcome
- Leaf Pge0
- Direction
- positively correlatede0
- Value
- r = 0.87e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf Pg was positively correlated with N (r = 0.87) and approached zero at approximately 1.75% N, a concentration similar to that of senesced, recently abscised leaves.”
t0“Soybeans”
Claim · model-written summary
Leaf photosynthesis approached zero at about 1.75% N.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- leafe0
- Outcome
- Leaf Pge0
- Direction
- approached zeroe0
- Value
- 1.75% Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf Pg was positively correlated with N (r = 0.87) and approached zero at approximately 1.75% N, a concentration similar to that of senesced, recently abscised leaves.”
t0“Soybeans”
Claim · model-written summary
Maximum leaf photosynthesis was predicted at 4.6 to 6.0% leaf N.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum Pg was predicted at 4.6 to 6.0% leaf N.”
t0“Soybeans”
Claim · model-written summary
Leaf photosynthesis and leaf P percentage correlated positively.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- Leafe0
- Outcome
- Leaf Pge0
- Direction
- positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf Pg and percent P were also positively correlated.”
t0“Soybeans”
Claim · model-written summary
The authors propose using the leaf photosynthesis–N relationship to model decline during seed filling.
- Taxon
- soybeanGlycine maxt0
- Outcome
- model photosynthetic decline during seed‐fillinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The relationship of Pg to leaf N during N removal from leaves can potentially be used to model photosynthetic decline during seed‐filling.”
t0“Soybeans”
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