Abstract
We treated two citrus cultivars with a complete fertilizer diluted to 25, 100, 200, or 400 ppm N to test whether increasing fertilizer concentration alters root and leaf chemistry and decreases resistance of citrus to root-feeding larvae of Diaprepes abbreviatus L. Roots and leaves of better-nourished ‘sour orange’ (Citrus aurantium L.) had larger amounts of total proteins and increased activities of enzymes associated with resistance than did plants given 25 ppm N. The fertilizer effect was less consistent for ‘Swingle citrumelo’ (C. paradise Macf. × Poncirus trifoliate L.), which has greater resistance to D. abbreviatus. Herbivory increased root protein content and peroxidase but decreased activities of chitinase and β-1,3-glucanase, which are enzymes associated with resistance to microbial pathogens. When significant, the effect of root herbivory on enzyme activities in leaves was opposite the effects on roots. Fertilizer and herbivory rarely interacted, indicating enzyme induction was not a function of nutrient supply. Fertilizer did not affect total phenolics in roots of either citrus, but root herbivory increased levels in ‘sour orange’. Despite elevated levels of putative defense proteins, ‘sour orange’ given ≥100 ppm N produced 50% greater total larval mass per pot than did plants given 25 ppm N. Fertilizer concentration did not affect mass of larvae on ‘Swingle citrumelo’ roots and did not affect larval mortality for either citrus cultivar. Our results concerning a root herbivore are consistent with the body of studies of folivores that have demonstrated that increased fertilizer has no effect or increases herbivore performance.
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Claims 13
Claim · model-written summary
Better-nourished sour orange had more root and leaf protein.
- Taxon
- Citrus aurantium L.
Citrus ×aurantiume0 - Material
- ‘sour orange’e0
- Treatment
- better-nourishede0
- Outcome
- total proteinse0
- Direction
- larger amountse0
- Comparator
- 25 ppm Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Roots and leaves of better-nourished ‘sour orange’ (Citrus aurantium L.) had larger amounts of total proteins and increased activities of enzymes associated with resistance than did plants given 25 ppm N”
Claim · model-written summary
Better-nourished sour orange had higher resistance-associated enzyme activity.
- Taxon
- Citrus aurantium L.Citrus ×aurantiume0
- Material
- ‘sour orange’e0
- Treatment
- better-nourishede0
- Outcome
- activities of enzymes associated with resistancee0
- Direction
- increasede0
- Comparator
- 25 ppm Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Roots and leaves of better-nourished ‘sour orange’ (Citrus aurantium L.) had larger amounts of total proteins and increased activities of enzymes associated with resistance than did plants given 25 ppm N”
Claim · model-written summary
Fertilizer effects on Swingle citrumelo were less consistent.
Verbatim
e0“The fertilizer effect was less consistent for ‘Swingle citrumelo’ (C. paradise Macf. × Poncirus trifoliate L.)”
Claim · model-written summary
Swingle citrumelo had greater resistance to D. abbreviatus.
- Taxon
- C. paradise Macf. × Poncirus trifoliate L.t0
- Interactor
- D. abbreviatus
Diaprepes abbreviatuse0pestt1 - Outcome
- resistance to D. abbreviatuse0
- Direction
- greatere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which has greater resistance to D. abbreviatus”
t0“C. paradise Macf. × Poncirus trifoliate L.”
t1“D. abbreviatus”
Claim · model-written summary
Herbivory increased root protein and peroxidase.
- Treatment
- Herbivorye0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- root protein content and peroxidasee0
- Direction
- increasede0
CitrusNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Herbivory increased root protein content and peroxidase”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
Claim · model-written summary
Herbivory decreased root chitinase and β-1,3-glucanase activity.
- Treatment
- Herbivoryt1
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- activities of chitinase and β-1,3-glucanasee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased activities of chitinase and β-1,3-glucanase”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
t1“Herbivory”
Claim · model-written summary
Where significant, herbivory changed leaf enzyme activities opposite to root responses.
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- enzyme activities in leavese0
- Qualifier
- opposite the effects on rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When significant, the effect of root herbivory on enzyme activities in leaves was opposite the effects on roots”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
Claim · model-written summary
Fertilizer and herbivory rarely interacted for enzyme induction.
- Treatment
- Fertilizer and herbivorye0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- enzyme inductione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilizer and herbivory rarely interacted, indicating enzyme induction was not a function of nutrient supply”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
Claim · model-written summary
Fertilizer did not alter root total phenolics in either cultivar.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilizer did not affect total phenolics in roots of either citrus”
Claim · model-written summary
Root herbivory increased phenolics in sour orange.
- Material
- ‘sour orange’e0
- Treatment
- root herbivorye0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- total phenolicst1
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“root herbivory increased levels in ‘sour orange’”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
t1“total phenolics”
Claim · model-written summary
Sour orange at ≥100 ppm N produced 50% more larval mass than at 25 ppm N.
- Material
- ‘sour orange’e0
- Treatment
- ≥100 ppm Ne0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- total larval mass per pote0
- Direction
- greatere0
- Value
- 50%e0
- Comparator
- 25 ppm Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“‘sour orange’ given ≥100 ppm N produced 50% greater total larval mass per pot than did plants given 25 ppm N”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
Claim · model-written summary
Fertilizer concentration did not change larval mass on Swingle citrumelo roots.
- Material
- ‘Swingle citrumelo’e0
- Treatment
- Fertilizer concentratione0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust0pest
- Outcome
- mass of larvaee0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilizer concentration did not affect mass of larvae on ‘Swingle citrumelo’ roots”
t0“Citrus Resistance to Root Herbivory by Diaprepes abbreviatus”
Claim · model-written summary
Fertilizer did not change larval mortality in either citrus cultivar.
- Treatment
- Fertilizer concentrationt0
- Interactor
- Diaprepes abbreviatusDiaprepes abbreviatust1pest
- Outcome
- larval mortalitye0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not affect larval mortality for either citrus cultivar”
t0“Fertilizer concentration”
t1“Diaprepes abbreviatus”
The same questions in other papers
fertilization · quality: phytochemicals · CitrusPositive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- 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.