Abstract
Grafting is a widely used technique to improve stress tolerance in horticultural plants. However, little is known about how grafting affects citrus growth under low-nitrogen (N) stress. To investigate the responses of different grafting combinations to low N availability, we examined root morphology, photosynthesis, chlorophyll fluorescence and semi-quantitative mineral profiles in grafted and ungrafted citrus plants subjected to two N levels (10 and 0.15 mM NO3− -N) under potted conditions. Analyses were performed on roots and leaves of six plant combinations: ungrafted Trifoliate orange (Poncitrus trifoliata L. Raf., Pt) and red tangerine (Citrus reticulata Blanco, Cr); self-grafted combinations (Pt/Pt and Cr/Cr); and reciprocal heterografts (Pt/Cr and Cr/Pt). Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters. The highest net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’) were observed in the Pt and Pt/Pt plants. Low-N stress reduced chloroplastid pigment contents and limited photosynthetic rates. Under 10 mM N treatment, the Fv/Fm values of Pt, Cr, Pt/Pt, and Cr/Pt were approximately 0.82, whereas those of Pt/Cr and Cr/Cr were below 0.82, suggesting lower maximal PSII efficiency in combinations with Cr rootstock. Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased. Overall, combinations with Pt rootstock (Pt/Pt and Cr/Pt) showed better growth and photosynthetic performance, and more stable mineral profiles under low-N stress than combinations with Cr rootstock (Cr/Cr and Pt/Cr). These findings provide a physiological basis for understanding rootstock-specific responses to low-N stress under controlled conditions.
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Claims 15
Claim · model-written summary
Low nitrogen decreased plant height by 12.3–36.8% across six citrus combinations.
CitrusNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters.”
t0“Citrus Seedlings”
Claim · model-written summary
Low nitrogen decreased stem diameter by 2.9–31.8% across six citrus combinations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters.”
t0“Citrus Seedlings”
Claim · model-written summary
Low nitrogen decreased leaf area by 18.2–26.3% across six citrus combinations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters.”
t0“Citrus Seedlings”
Claim · model-written summary
Low nitrogen decreased SPAD by 11.6–24.5% across six citrus combinations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low-N stress, plant height decreased by 12.3–36.8%, stem diameter by 2.9–31.8%, leaf area by 18.2–26.3%, and SPAD by 11.6–24.5% across the six combinations, with the Cr/Cr combination showing the largest reductions in all parameters.”
t0“Citrus Seedlings”
Claim · model-written summary
Pt and Pt/Pt plants had the highest net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs).
- Material
- Pt and Pt/Pte0
- Outcome
- net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs)e0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’) were observed in the Pt and Pt/Pt plants.”
t0“Citrus Seedlings”
Claim · model-written summary
Pt and Pt/Pt plants had the highest electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’).
- Material
- Pt and Pt/Pte0
- Outcome
- electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’)e0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), electron transport rate (ETR), maximum quantum efficiency of PSII (Fv/Fm) and effective quantum efficiency of PSII (Fv’/Fm’) were observed in the Pt and Pt/Pt plants.”
t0“Citrus Seedlings”
Claim · model-written summary
Low nitrogen reduced chloroplastid pigment contents and photosynthetic rates.
- Treatment
- Low-N stresse0
- Outcome
- chloroplastid pigment contents and limited photosynthetic ratese0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low-N stress reduced chloroplastid pigment contents and limited photosynthetic rates.”
t0“Citrus Seedlings”
Claim · model-written summary
At 10 mM N, Pt, Cr, Pt/Pt and Cr/Pt had Fv/Fm values around 0.82.
- Material
- Pt, Cr, Pt/Pt, and Cr/Pte0
- Treatment
- 10 mM N treatmente0
- Outcome
- Fv/Fm valuese0
- Value
- approximately 0.82e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under 10 mM N treatment, the Fv/Fm values of Pt, Cr, Pt/Pt, and Cr/Pt were approximately 0.82, whereas those of Pt/Cr and Cr/Cr were below 0.82, suggesting lower maximal PSII efficiency in combinations with Cr rootstock.”
t0“Citrus Seedlings”
Claim · model-written summary
At 10 mM N, Pt/Cr and Cr/Cr had Fv/Fm below 0.82.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under 10 mM N treatment, the Fv/Fm values of Pt, Cr, Pt/Pt, and Cr/Pt were approximately 0.82, whereas those of Pt/Cr and Cr/Cr were below 0.82, suggesting lower maximal PSII efficiency in combinations with Cr rootstock.”
t0“Citrus Seedlings”
Claim · model-written summary
Under low nitrogen, leaf and root sap levels of P, K, Ca increased.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased.”
t0“Citrus Seedlings”
Claim · model-written summary
Under low nitrogen, leaf and root sap levels of Mg, and Fe increased.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased.”
t0“Citrus Seedlings”
Claim · model-written summary
Under low nitrogen, leaf and root sap levels of N, Cu, Zn decreased.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased.”
t0“Citrus Seedlings”
Claim · model-written summary
Under low nitrogen, leaf and root sap levels of B, and Mn decreased.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regarding mineral elements, under low-N stress, the relative levels of P, K, Ca, Mg, and Fe in leaf and root sap increased, while those of N, Cu, Zn, B, and Mn decreased.”
t0“Citrus Seedlings”
Claim · model-written summary
Pt-rootstock combinations had better growth and photosynthetic performance under low nitrogen than Cr-rootstock combinations.
- Material
- Pt/Pt and Cr/Pte0
- Outcome
- growth and photosynthetic performancee0
- Direction
- bettere0
- Qualifier
- under low-N stresse0
- Comparator
- Cr/Cr and Pt/Cre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overall, combinations with Pt rootstock (Pt/Pt and Cr/Pt) showed better growth and photosynthetic performance, and more stable mineral profiles under low-N stress than combinations with Cr rootstock (Cr/Cr and Pt/Cr).”
t0“Citrus Seedlings”
Claim · model-written summary
Pt-rootstock combinations had more stable mineral profiles under low nitrogen than Cr-rootstock combinations.
- Material
- Pt/Pt and Cr/Pte0
- Outcome
- mineral profilese0
- Direction
- more stablee0
- Qualifier
- under low-N stresse0
- Comparator
- Cr/Cr and Pt/Cre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overall, combinations with Pt rootstock (Pt/Pt and Cr/Pt) showed better growth and photosynthetic performance, and more stable mineral profiles under low-N stress than combinations with Cr rootstock (Cr/Cr and Pt/Cr).”
t0“Citrus Seedlings”
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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.