Abstract
Abstract A pot‐culture experiment was conducted under outdoor conditions to determine effects of nitrogen (N) deficiency on big bluestem ( Andropogon gerardii Vitman, cv Bonelli) growth, photosynthesis and leaf reflectance (R) properties. Big bluestem was seeded on 14 May 2004 and grown in 120 twelve‐litre pots filled with fine sand and irrigated with Hoagland’s nutrient solution (with 81 mg L −1 as N). Treatments initiated at 60 days after sowing (DAS) included: (1) the control (100N) continued receiving the Hoagland’s nutrient solution; (2) reduced N to 20 % of the control (20N); and (3) withheld N from the solution (0N). Chlorophyll (Chl) and N, and reflectance of the uppermost fully expanded leaves were determined at 10‐d intervals from 60 to 115 DAS during the N treatments. Plant growth and developmental parameters were measured at the end of the experiment, 115 DAS. Nitrogen deficiency caused a reduction in leaf Chl content, rate of photosynthesis ( A ), and dry weight (DW) of biomass components. Deficit N increased leaf reflectance at 555 (R555) and 715 (R715) nm and caused a shift in red‐edge (685–745 nm) to shorter wavelengths. Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R545/R1605 (r 2 = 0.82) and R555/R405 (r 2 = 0.81), respectively, but also the first derivatives of the reflectance (d R /dλ) in red‐edge centred 690 or 700 nm (r 2 = 0.74–0.83). Leaf and panicle DW had the greatest, while root DW had the smallest decrease under N deficiency. It was concluded that the specific reflectance ratios or d R /dλ may be used for rapid and non‐destructive estimation of leaf Chl and plant N status of big bluestem to detect changes in N for appropriate nitrogen management strategies during the growing season.
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Claims 10
Claim · model-written summary
Nitrogen deficiency reduced leaf chlorophyll content.
- Taxon
- Andropogon gerardii
Andropogon gerardit0 - Treatment
- Nitrogen deficiencye0
- Outcome
- leaf Chl contente0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen deficiency caused a reduction in leaf Chl content, rate of photosynthesis ( A ), and dry weight (DW) of biomass components.”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Nitrogen deficiency reduced photosynthesis.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Treatment
- Nitrogen deficiencye0
- Outcome
- rate of photosynthesise0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen deficiency caused a reduction in leaf Chl content, rate of photosynthesis ( A ), and dry weight (DW) of biomass components.”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Nitrogen deficiency reduced biomass component dry weight.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Treatment
- Nitrogen deficiencye0
- Outcome
- dry weight (DW) of biomass componentse0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen deficiency caused a reduction in leaf Chl content, rate of photosynthesis ( A ), and dry weight (DW) of biomass components.”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Nitrogen deficit increased leaf reflectance at 555 and 715 nm.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Treatment
- Deficit Ne0
- Outcome
- leaf reflectance at 555 (R555) and 715 (R715) nme0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Deficit N increased leaf reflectance at 555 (R555) and 715 (R715) nm”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Nitrogen deficit shifted the red edge to shorter wavelengths.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Treatment
- Deficit Ne0
- Outcome
- red‐edge (685–745 nm)e0
- Direction
- shorter wavelengthse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Deficit N increased leaf reflectance at 555 (R555) and 715 (R715) nm and caused a shift in red‐edge (685–745 nm) to shorter wavelengths.”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Leaf nitrogen correlated linearly with R545/R1605.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Outcome
- Leaf Ne0
- Value
- r 2 = 0.82e0
- Comparator
- R545/R1605e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R545/R1605 (r 2 = 0.82) and R555/R405 (r 2 = 0.81), respectively”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Leaf chlorophyll correlated linearly with R555/R405.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Outcome
- Chl concentrationse0
- Value
- r 2 = 0.81e0
- Comparator
- R555/R405e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R545/R1605 (r 2 = 0.82) and R555/R405 (r 2 = 0.81), respectively”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Leaf nitrogen and chlorophyll correlated with red edge reflectance derivatives.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Outcome
- Leaf N and Chl concentrationse0
- Value
- r 2 = 0.74–0.83e0
- Comparator
- first derivatives of the reflectance (d R /dλ)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R545/R1605 (r 2 = 0.82) and R555/R405 (r 2 = 0.81), respectively, but also the first derivatives of the reflectance (d R /dλ) in red‐edge centred 690 or 700 nm (r 2 = 0.74–0.83).”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Under nitrogen deficiency, leaf and panicle dry weight decreased most, and root dry weight least.
- Taxon
- Andropogon gerardiiAndropogon gerardit0
- Treatment
- N deficiencye0
- Outcome
- Leaf and panicle DWe0
- Direction
- greateste0
- Qualifier
- root DW had the smallest decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf and panicle DW had the greatest, while root DW had the smallest decrease under N deficiency.”
t0“Big Bluestem (Andropogon gerardii)”
Claim · model-written summary
Reflectance ratios or red edge derivatives may permit rapid nondestructive estimation of chlorophyll and nitrogen status.
- Taxon
- big bluesteme0
- Outcome
- estimation of leaf Chl and plant N statuse0
- Qualifier
- rapid and non‐destructivee0
Not reportedComparatorValue
Verbatim
e0“specific reflectance ratios or d R /dλ may be used for rapid and non‐destructive estimation of leaf Chl and plant N status of big bluestem”
The same questions in other papers
nitrogen · growth · Andropogon gerardiResults agree
1 paper in the same direction as this paper
This paper is about lacking the nutrient, so it counts the other way round here.
- 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.