Abstract
The relationships between leaf nutrient content, leaf age, and within-canopy light exposure were studied in 10–11-year-old Macadamia integrifolia cvv. 660, 781, and 344 at Alstonville (28°59'S, 149°E), New South Wales, during autumn and spring 1996. Quantum point sensors were placed at 16 positions in the canopy to give mean 24-hourly photosynthetic photon flux density (PFD) readings, which ranged from 13 to 540 mol/m2.sec. At each of these positions, the youngest terminal leaf (YTL), the youngest fully expanded leaf (FEL) from a current flush, and a 6–7-month-old hardened off leaf (HOL) were sampled. In 1997, at 12 sites in the Alstonville district, leaves of cv. 344 were sampled (FEL and HOL) at 5 equidistant positions from the bottom, a height of 1.2 m (position 1), to the top (position 5), on the N–NE side of trees in late spring. The sites varied in canopy density from 50% to 95% ground cover, and PFD from the bottom shaded position to the top exposed position in the canopy across all sites increased by a factor of 1.3 to 17.9. At Alstonville, leaf parameters [N%, P%, specific leaf weight (SLW), N amount per unit leaf area (N area), and P area] increased ( P < 0.001) with increasing PFD. Using regression analyses, the maximum R 2 was 0.59. Age affected ( P < 0.05) leaf parameters: for N%, N area, and SLW, HOL > FEL = YTL; and for P% and P area, YTL = FEL > HOL. Cultivar did not affect ( P > 0.05) N%, N area or SLW; for P% and P area, cv. 660 > 781 > 344 ( P < 0.05). At the Alstonville district sites, leaf parameters increased with PFD ( P < 0.05). At each tree sampling position there was a weak negative correlation ( P < 0.05) between the leaf parameters and percentage ground cover across all sites, which declined with height (and PFD). Nitrogen area and P area gave the highest R values (–0.60 and –0.40 at low canopy positions), and neither was a suitable replacement for percentage ground cover as a leaf-based shading indicator. The slope of the regression line (regression coefficient) between a leaf parameter and tree height for each macadamia site was determined. The regression coefficient for N area gave the best correlation with percentage ground cover ( R 2 = 0.55, P < 0.01) and may be useful as a leaf-based shading indicator. At position 1, HOL N concentration ranged from 1.3% to 1.8% and P concentration from 0.06% to 0.11% across all sites. At each of the 5 tree positions, the N parameters were very poorly correlated with kernel yield, and for the HOL P parameters, there was a weak negative correlation ( R = –0.521 to –0.673, P < 0.05) at tree positions 1 and 2 with kernel yield. Current recommendations to reduce macadamia leaf N concentrations because of detrimental effects of high leaf N on yield were not supported by the current study. Modification of the current diagnostic leaf sampling protocol is recommended to avoid the reduction in leaf N and P concentrations through shading and the cultivar effects on P concentration. We conclude that the current diagnostic leaf N and P standards cannot reliably diagnose the nutritional status of macadamia orchards.
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Claims 20
Claim · model-written summary
At Alstonville, leaf N%, P% and specific leaf weight increased significantly with PFD.
- Taxon
- Macadamia integrifolia
Macadamia integrifoliae1 - Treatment
- PFDe0
- Outcome
- N%, P%, specific leaf weight (SLW)e0
- Direction
- increasede0
- Setting
- Alstonvillee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At Alstonville, leaf parameters [N%, P%, specific leaf weight (SLW), N amount per unit leaf area (N area), and P area] increased ( P < 0.001) with increasing PFD.”
e1“Macadamia integrifolia cvv. 660, 781, and 344 at Alstonville”
Claim · model-written summary
At Alstonville, leaf N amount per area and P area increased significantly with PFD.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Treatment
- PFDe0
- Outcome
- N amount per unit leaf area (N area), and P areae0
- Direction
- increasede0
- Setting
- Alstonvillee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At Alstonville, leaf parameters [N%, P%, specific leaf weight (SLW), N amount per unit leaf area (N area), and P area] increased ( P < 0.001) with increasing PFD.”
e1“Macadamia integrifolia”
Claim · model-written summary
Regression analyses gave a maximum R squared of 0.59.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- R 2e0
- Value
- 0.59e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Using regression analyses, the maximum R 2 was 0.59.”
e1“Macadamia integrifolia”
Claim · model-written summary
HOL had higher N%, N area and SLW than FEL and YTL, which were equal.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Organ / stage
- HOLe0
- Outcome
- N%, N area, and SLWe0
- Direction
- >e0
- Comparator
- FEL = YTLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Age affected ( P < 0.05) leaf parameters: for N%, N area, and SLW, HOL > FEL = YTL; and for P% and P area, YTL = FEL > HOL.”
e1“Macadamia integrifolia”
Claim · model-written summary
YTL and FEL had equal P% and P area, both exceeding HOL.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Organ / stage
- YTL = FELe0
- Outcome
- P% and P areae0
- Direction
- >e0
- Comparator
- HOLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Age affected ( P < 0.05) leaf parameters: for N%, N area, and SLW, HOL > FEL = YTL; and for P% and P area, YTL = FEL > HOL.”
e1“Macadamia integrifolia”
Claim · model-written summary
Cultivar did not significantly affect N%, N area or SLW.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Material
- Cultivare0
- Outcome
- N%, N area or SLWe0
- Direction
- did not affecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cultivar did not affect ( P > 0.05) N%, N area or SLW; for P% and P area, cv. 660 > 781 > 344 ( P < 0.05).”
e1“Macadamia integrifolia”
Claim · model-written summary
Cultivar 660 exceeded 781 and 344 in P% and P area.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Material
- 660e0
- Outcome
- P% and P areae0
- Direction
- >e0
- Qualifier
- 660 > 781 > 344e0
- Comparator
- 781e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for P% and P area, cv. 660 > 781 > 344 ( P < 0.05).”
e1“Macadamia integrifolia”
Claim · model-written summary
Cultivar 781 exceeded 344 in P% and P area.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Material
- 781e0
- Outcome
- P% and P areae0
- Direction
- >e0
- Comparator
- 344e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for P% and P area, cv. 660 > 781 > 344 ( P < 0.05).”
e1“Macadamia integrifolia”
Claim · model-written summary
At district sites, leaf parameters increased significantly with PFD.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Treatment
- PFDe0
- Outcome
- leaf parameterse0
- Direction
- increasede0
- Setting
- Alstonville districte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the Alstonville district sites, leaf parameters increased with PFD ( P < 0.05).”
e1“Macadamia integrifolia”
Claim · model-written summary
Leaf parameters correlated weakly negatively with ground cover; the correlation declined with height and PFD.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- leaf parameterse0
- Direction
- negative correlatione0
- Qualifier
- declined with height (and PFD)e0
- Comparator
- percentage ground covere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At each tree sampling position there was a weak negative correlation ( P < 0.05) between the leaf parameters and percentage ground cover across all sites, which declined with height (and PFD).”
e1“Macadamia integrifolia”
Claim · model-written summary
N area had R = –0.60 at low canopy positions and was unsuitable as a replacement shading indicator.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Organ / stage
- Nitrogen areae0
- Outcome
- R valuese0
- Value
- –0.60e0
- Qualifier
- low canopy positionse0
- Comparator
- percentage ground covere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen area and P area gave the highest R values (–0.60 and –0.40 at low canopy positions), and neither was a suitable replacement for percentage ground cover as a leaf-based shading indicator.”
e1“Macadamia integrifolia”
Claim · model-written summary
P area had R = –0.40 at low canopy positions and was unsuitable as a replacement shading indicator.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- R valuese0
- Value
- –0.40e0
- Qualifier
- low canopy positionse0
- Comparator
- percentage ground covere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen area and P area gave the highest R values (–0.60 and –0.40 at low canopy positions), and neither was a suitable replacement for percentage ground cover as a leaf-based shading indicator.”
e1“Macadamia integrifolia”
Claim · model-written summary
The N-area regression coefficient best correlated with ground cover (R squared 0.55) and may be useful as a shading indicator.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- regression coefficient for N areae0
- Value
- 0.55e0
- Qualifier
- may be useful as a leaf-based shading indicatore0
- Comparator
- percentage ground covere0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The regression coefficient for N area gave the best correlation with percentage ground cover ( R 2 = 0.55, P < 0.01) and may be useful as a leaf-based shading indicator.”
e1“Macadamia integrifolia”
Claim · model-written summary
At position 1, HOL N concentration ranged from 1.3% to 1.8%.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Organ / stage
- HOLe0
- Outcome
- N concentratione0
- Value
- 1.3% to 1.8%e0
- Qualifier
- position 1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At position 1, HOL N concentration ranged from 1.3% to 1.8% and P concentration from 0.06% to 0.11% across all sites.”
e1“Macadamia integrifolia”
Claim · model-written summary
At position 1, HOL P concentration ranged from 0.06% to 0.11%.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Organ / stage
- HOLe0
- Outcome
- P concentratione0
- Value
- 0.06% to 0.11%e0
- Qualifier
- position 1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At position 1, HOL N concentration ranged from 1.3% to 1.8% and P concentration from 0.06% to 0.11% across all sites.”
e1“Macadamia integrifolia”
Claim · model-written summary
N parameters were very poorly correlated with kernel yield at all five tree positions.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- N parameterse0
- Qualifier
- each of the 5 tree positionse0
- Comparator
- kernel yielde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At each of the 5 tree positions, the N parameters were very poorly correlated with kernel yield”
e1“Macadamia integrifolia”
Claim · model-written summary
HOL P parameters correlated weakly negatively with kernel yield at positions 1 and 2.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- HOL P parameterse0
- Direction
- negative correlatione0
- Value
- –0.521 to –0.673e0
- Qualifier
- tree positions 1 and 2e0
- Comparator
- kernel yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for the HOL P parameters, there was a weak negative correlation ( R = –0.521 to –0.673, P < 0.05) at tree positions 1 and 2 with kernel yield.”
e1“Macadamia integrifolia”
Claim · model-written summary
The study did not support recommendations to reduce leaf N because of detrimental yield effects.
- Outcome
- recommendations to reduce macadamia leaf N concentrationse0
- Qualifier
- not supported by the current studye0
.JPG?width=60){kind=small}
MacadamiaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“Current recommendations to reduce macadamia leaf N concentrations because of detrimental effects of high leaf N on yield were not supported by the current study.”
Claim · model-written summary
Diagnostic leaf sampling should be modified to avoid shading reductions in N and P and cultivar effects on P.
- Taxon
- Macadamia integrifoliaMacadamia integrifoliae1
- Outcome
- Modification of the current diagnostic leaf sampling protocole0
- Qualifier
- avoid the reduction in leaf N and P concentrations through shading and the cultivar effects on P concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Modification of the current diagnostic leaf sampling protocol is recommended to avoid the reduction in leaf N and P concentrations through shading and the cultivar effects on P concentration.”
e1“Macadamia integrifolia”
Claim · model-written summary
Current diagnostic leaf N and P standards cannot reliably diagnose macadamia orchard nutritional status.
- Outcome
- cannot reliably diagnose the nutritional statuse0
- Qualifier
- current diagnostic leaf N and P standardse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We conclude that the current diagnostic leaf N and P standards cannot reliably diagnose the nutritional status of macadamia orchards.”