Abstract
Abstract. The role of phosphorus (P) in leaf magnesium (Mg) concentrations and photosynthesis was investigated in field and glasshouse experiments with grapevine ( Vitis vinifera L., cvs. Chenin blane. Chardonnay, and Carignane). In the field, leaves of vines growing on soil with low available P exhibited symptoms of Mg deficiency and had low P and Mg concentrations. The rate of photosynthesis for leaves of untreated control vines was approximately 0.7 nmol CO 2 cm 2 s 1 . When P fertilizer was applied to the soil, Mg deficiency symptoms were eliminated, and leaf P and Mg concentrations increased to above critical levels. When Mg was applied as a foliar spray, leaf Mg increased to above critical levels, but leaf P did not change significantly. In both experiments, the rate of photosynthesis increased to greater than 1.0 nmol CO 2 cm 2 s 1 after nutrient applications. Thus, under low soil P conditions, leaf photosynthesis was limited by leaf Mg concentrations. In glasshouse experiments in which vines were grown with and without P for three seasons, Mg accumulated in large roots of ‐ P vines to approximately twice the concentration found in roots of + P vines. Analysis of the xylem exudate from detopped plants showed that Mg concentration in xylem sap of + P vines was twice as great as that in ‐ P vines. When P was supplied to ‐ P vines, the concentration of Mg increased to the concentration of + P vines within 2 days. The results show that the translocation of Mg from roots to shoots of grapevine is dependent upon P supply to the roots and suggest that Mg translocation is more sensitive than uptake to P supply.
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Claims 11
Claim · model-written summary
Field vines on low phosphorus soil had magnesium deficiency symptoms and low leaf phosphorus and magnesium.
VitisNot reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaves of vines growing on soil with low available P exhibited symptoms of Mg deficiency and had low P and Mg concentrations”
t0“grapevine”
Claim · model-written summary
Phosphorus fertilizer eliminated leaf magnesium deficiency symptoms.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When P fertilizer was applied to the soil, Mg deficiency symptoms were eliminated”
t0“grapevine”
Claim · model-written summary
Phosphorus fertilizer increased leaf phosphorus and magnesium concentrations above critical levels.
- Treatment
- P fertilizere0
- Outcome
- leaf P and Mg concentrationse0
- Direction
- increasede0
- Qualifier
- above critical levelse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When P fertilizer was applied to the soil, Mg deficiency symptoms were eliminated, and leaf P and Mg concentrations increased to above critical levels”
t0“grapevine”
Claim · model-written summary
Foliar magnesium raised leaf magnesium above critical levels.
- Treatment
- Mg was applied as a foliar spraye0
- Outcome
- leaf Mge0
- Direction
- increasede0
- Qualifier
- above critical levelse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When Mg was applied as a foliar spray, leaf Mg increased to above critical levels”
t0“grapevine”
Claim · model-written summary
Foliar magnesium did not significantly change leaf phosphorus.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When Mg was applied as a foliar spray, leaf Mg increased to above critical levels, but leaf P did not change significantly”
t0“grapevine”
Claim · model-written summary
Nutrient applications increased photosynthesis above 1.0 nmol CO 2 cm 2 s 1 from approximately 0.7 in controls.
- Treatment
- nutrient applicationse1
- Outcome
- rate of photosynthesise1
- Direction
- increasede1
- Value
- greater than 1.0 nmol CO 2 cm 2 s 1e1
- Qualifier
- approximately 0.7 nmol CO 2 cm 2 s 1e0
- Comparator
- untreated control vinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of photosynthesis for leaves of untreated control vines was approximately 0.7 nmol CO 2 cm 2 s 1 .”
e1“In both experiments, the rate of photosynthesis increased to greater than 1.0 nmol CO 2 cm 2 s 1 after nutrient applications.”
t0“grapevine”
Claim · model-written summary
Magnesium in large roots without phosphorus was approximately twice that with phosphorus.
- Outcome
- Mg accumulated in large rootse0
- Direction
- twicee0
- Value
- approximately twicee0
- Comparator
- + P vinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg accumulated in large roots of ‐ P vines to approximately twice the concentration found in roots of + P vines”
t0“grapevine”
Claim · model-written summary
Xylem sap magnesium concentration with phosphorus was twice that without phosphorus.
- Outcome
- Mg concentration in xylem sape0
- Direction
- twice as greate0
- Value
- twice as greate0
- Comparator
- ‐ P vinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg concentration in xylem sap of + P vines was twice as great as that in ‐ P vines”
t0“grapevine”
Claim · model-written summary
Supplying phosphorus to deficient vines raised magnesium concentration to that of phosphorus supplied vines within 2 days.
- Treatment
- P was suppliede0
- Outcome
- concentration of Mge0
- Direction
- increasede0
- Qualifier
- within 2 dayse0
- Comparator
- + P vinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When P was supplied to ‐ P vines, the concentration of Mg increased to the concentration of + P vines within 2 days”
t0“grapevine”
Claim · model-written summary
Magnesium translocation from roots to shoots depends on phosphorus supply to roots.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“translocation of Mg from roots to shoots of grapevine is dependent upon P supply to the roots”
Claim · model-written summary
Magnesium translocation may be more sensitive to phosphorus supply than uptake.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg translocation is more sensitive than uptake to P supply”
t0“grapevine”
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