Abstract
Fruit production of sweet orange ( Citrus sinensis ) in Florida has been declining with the presence of Huanglongbing [HLB; Candidatus Liberibacter asiaticus (CLas)] disease. Through disruption of the balance of endogenous hormone levels, the disease has negative impacts on fruit development, mature fruit retention, and overall tree health. Thus, the goal of this research was to determine whether plant growth regulator gibberellic acid (GA 3 ) can be used to improve the production issues caused by HLB. For ‘Valencia’ sweet orange, although foliar applied GA 3 from September to January (33 mg·L −1 for five applications) resulted in 50% decrease in bloom the following spring (results presented in Tang et al., 2021), this treatment did not cause reduction in yield of current and subsequent crops. Moreover, a 30% average increase in yield in GA 3 -treated trees was observed over a period of 4 years. The size of mature fruit was also increased (by 4% to 5%) with reduced fruit drop rate near harvest in GA 3 -treated trees compared with nontreated control trees. Furthermore, the canopy density, an indicator of HLB severity, was maintained in trees applied with GA 3 (from 90.8% light interception to 90.4%). In contrast, there was a substantial decrease in canopy density for control trees (from 91.6% to 84.0%). Gene expression analysis of abscission zone and leaves indicated that GA 3 -treated trees had enhanced oxidative stress mitigation mechanism and plant defense response. Given that there is no cure for HLB, these results presented a possible remedy of using GA 3 in sustaining tree health for field-grown sweet orange affected by HLB.
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Claims 9
Claim · model-written summary
GA 3 did not reduce yield of current or subsequent Valencia orange crops.
- Taxon
- sweet orange
Citrus sinensise0 - Material
- ‘Valencia’e0
- Treatment
- foliar applied GA 3 from September to January (33 mg·L −1 for five applications)e0
- Interactor
- Candidatus Liberibacter asiaticus
Candidatus Liberibacter asiaticuse1pathogen - Outcome
- yield of current and subsequent cropse0
- Direction
- did not cause reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For ‘Valencia’ sweet orange, although foliar applied GA 3 from September to January (33 mg·L −1 for five applications) resulted in 50% decrease in bloom the following spring (results presented in Tang et al., 2021), this treatment did not cause reduction in yield of current and subsequent crops”
t0“Huanglongbing-affected Sweet Orange Trees”
e1“Huanglongbing [HLB; Candidatus Liberibacter asiaticus (CLas)] disease”
Claim · model-written summary
GA 3 increased yield by an average of 30% across four years.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- GA 3 -treated treese0
- Outcome
- yielde0
- Direction
- increasee0
- Value
- 30%e0
- Qualifier
- over a period of 4 yearse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Moreover, a 30% average increase in yield in GA 3 -treated trees was observed over a period of 4 years”
t0“Sweet Orange Trees”
Claim · model-written summary
GA 3 increased mature fruit size by 4% to 5% relative to nontreated controls.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- GA 3 -treated treese0
- Outcome
- size of mature fruite0
- Direction
- increasede0
- Value
- 4% to 5%e0
- Comparator
- nontreated control treese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The size of mature fruit was also increased (by 4% to 5%) with reduced fruit drop rate near harvest in GA 3 -treated trees compared with nontreated control trees”
t0“Sweet Orange Trees”
Claim · model-written summary
GA 3 reduced fruit drop near harvest relative to controls.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- GA 3 -treated treese0
- Outcome
- fruit drop ratee0
- Direction
- reducede0
- Qualifier
- near harveste0
- Comparator
- nontreated control treese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with reduced fruit drop rate near harvest in GA 3 -treated trees compared with nontreated control trees”
t0“Sweet Orange Trees”
Claim · model-written summary
GA 3 maintained canopy density, from 90.8% to 90.4% light interception.
- Taxon
- sweet orangeCitrus sinensist0
- Treatment
- GA 3e0
- Outcome
- canopy densitye0
- Direction
- maintainede0
- Value
- from 90.8% light interception to 90.4%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the canopy density, an indicator of HLB severity, was maintained in trees applied with GA 3 (from 90.8% light interception to 90.4%)”
t0“Sweet Orange Trees”
Claim · model-written summary
Control canopy density declined from 91.6% to 84.0%.
- Taxon
- sweet orangeCitrus sinensist0
- Material
- control treese0
- Outcome
- canopy densitye0
- Direction
- decreasee0
- Value
- from 91.6% to 84.0%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was a substantial decrease in canopy density for control trees (from 91.6% to 84.0%)”
t0“Sweet Orange Trees”
Claim · model-written summary
GA 3-treated trees showed enhanced oxidative stress mitigation gene expression.
- Taxon
- sweet orangeCitrus sinensist0
- Organ / stage
- abscission zone and leavese0
- Treatment
- GA 3 -treated treese0
- Outcome
- oxidative stress mitigation mechanisme0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gene expression analysis of abscission zone and leaves indicated that GA 3 -treated trees had enhanced oxidative stress mitigation mechanism and plant defense response”
t0“Sweet Orange Trees”
Claim · model-written summary
GA 3-treated trees showed enhanced plant defense response in expression analysis.
- Taxon
- sweet orangeCitrus sinensist0
- Organ / stage
- abscission zone and leavese0
- Treatment
- GA 3 -treated treese0
- Outcome
- plant defense responsee0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gene expression analysis of abscission zone and leaves indicated that GA 3 -treated trees had enhanced oxidative stress mitigation mechanism and plant defense response”
t0“Sweet Orange Trees”
Claim · model-written summary
The authors propose GA 3 as a remedy for sustaining HLB-affected sweet orange tree health.
- Taxon
- sweet orangeCitrus sinensise0
- Outcome
- using GA 3 in sustaining tree healthe0
- Setting
- field-growne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these results presented a possible remedy of using GA 3 in sustaining tree health for field-grown sweet orange affected by HLB”
The same questions in other papers
Gibberellic acid · growth · Citrus sinensis (sweet orange)Results differ
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- no effect
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See all 7 papers →Gibberellic acid · yield · Citrus sinensis (sweet orange)Results differ
22 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- negative
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See all 25 papers →Gibberellic acid · disease · Citrus sinensis (sweet orange)Results agree
4 papers in the same direction as this paper
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →application · Candidatus Liberibacter asiaticus · Citrus sinensis (sweet orange)Positive and negative results
1 in the opposite direction
- 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.