Abstract
Abstract Genetic variation in response to N-deficiency between tropical woody plants was assessed by growing two species each of the genus Melaleuca (M. leucadendra and M. cajuputi) and Eucalyptus (E. camaldulensis and E. tereticornis) hydroponically at two levels of N. Biomass, N content and carbohydrate contents of various plant parts, leaf photosynthetic rate, and photo assimilate distribution were determined in all the plants at both control N (2.14 mM) and low N (0.36 mM) levels. Although the Eucalyptus genotype grew faster than Melaleuca under control conditions, the reduction of stem elongation and growth by N-deficiency was more severe in Eucalyptus species than in Melaleuca. In the same way as the effect on growth, N-deficiency reduced the photosynthetic rate and leaf area in all the species. The better performance at a low N level of Melaleuca compared with Eucalyptus species could be attributed to the lower reduction of either the photosynthetic rate (M. cajuputi) or the leaf area expansion (M. leucadendra). M. cajuputi had a higher leaf N concentration that was less affected by stress in this species than in the others. N-deficiency induced a better N use efficiency in the leaves of Melaleuca by enhancing significantly the photosynthetic rate per unit leaf N. In response to N-deficiency, all the plants except for M. cajuputi accumulated a remarkably higher concentration of sugars and starch in different organs like roots, stem, and leaves, but the partitioning of photoassimilates was directed preferentially to the growth of the roots in Eucalyptus compared to Melaleuca species. Although the relative rate of biomass accumulation was positively correlated with the N concentration of the plant in both genera studied, the associations were stronger and regression coefficients were higher in Eucalyptus than in Melaleuca, with the crossing points of their regression lines occuring between the values in the low N and control treatments. The total N content in the plant exhibited a stronger correlation with N absorption per unit root weight than with the root weight. These results suggest that Melaleuca species are more resistant than Eucalyptus to N-deficiency owing to the maintenance of (1) a higher ability of N uptake by roots, (2) higher source activity represented by either the photosynthetic rate or the leaf area, and (3) more efficient N utilization of the source activity at a low N level in the growth medium. Key Words: Eucalyptus Melaleuca N-deficiencyphoto assimilate partitioningphotosynthesis
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Claims 11
Claim · model-written summary
N-deficiency reduced stem elongation and growth more severely in Eucalyptus species than in Melaleuca species, relative to control N.
- Taxon
- Eucalyptus species
.jpg?width=60)
Eucalyptuse0 - Treatment
- N-deficiencye0
- Outcome
- stem elongation and growthe0
- Direction
- reductione0
- Qualifier
- more severe in Eucalyptus species than in Melaleucae0
- Comparator
- control N (2.14 mM)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“the reduction of stem elongation and growth by N-deficiency was more severe in Eucalyptus species than in Melaleuca”
e1“control N (2.14 mM)”
Claim · model-written summary
N-deficiency reduced the photosynthetic rate and leaf area in all four Melaleuca and Eucalyptus species relative to control N.
Verbatim
e0“N-deficiency reduced the photosynthetic rate and leaf area in all the species”
e1“control N (2.14 mM)”
Claim · model-written summary
The better performance of Melaleuca than Eucalyptus species at low N is attributed to a lower reduction of photosynthetic rate (M. cajuputi) or leaf area expansion (M. leucadendra).
- Outcome
- better performance at a low N levele0
- Qualifier
- lower reduction of either the photosynthetic rate (M. cajuputi) or the leaf area expansion (M. leucadendra)e0
- Comparator
- Eucalyptus speciese0
MelaleucaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The better performance at a low N level of Melaleuca compared with Eucalyptus species could be attributed to the lower reduction of either the photosynthetic rate (M. cajuputi) or the leaf area expansion (M. leucadendra)”
Claim · model-written summary
M. cajuputi had a higher leaf N concentration that was less affected by stress than in the other species.
- Taxon
- M. cajuputi
.png?width=60)
Melaleuca cajuputie0 - Organ / stage
- leafe0
- Outcome
- leaf N concentratione0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.png?width=500)
Verbatim
e0“M. cajuputi had a higher leaf N concentration that was less affected by stress in this species than in the others”
Claim · model-written summary
N-deficiency significantly enhanced the photosynthetic rate per unit leaf N, giving better N use efficiency in Melaleuca leaves.
- Organ / stage
- leavese0
- Treatment
- N-deficiencye0
- Outcome
- photosynthetic rate per unit leaf Ne0
- Direction
- enhancinge0
- Comparator
- control N (2.14 mM)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N-deficiency induced a better N use efficiency in the leaves of Melaleuca by enhancing significantly the photosynthetic rate per unit leaf N”
e1“control N (2.14 mM)”
Claim · model-written summary
Under N-deficiency all plants except M. cajuputi accumulated remarkably higher concentrations of sugars and starch in roots, stem and leaves.
Verbatim
e0“In response to N-deficiency, all the plants except for M. cajuputi accumulated a remarkably higher concentration of sugars and starch in different organs like roots, stem, and leaves”
e1“control N (2.14 mM)”
Claim · model-written summary
Partitioning of photoassimilates was directed preferentially to root growth in Eucalyptus compared with Melaleuca species.
- Taxon
- EucalyptusEucalyptuse0
- Organ / stage
- rootse0
- Outcome
- partitioning of photoassimilatese0
- Comparator
- Melaleuca speciese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the partitioning of photoassimilates was directed preferentially to the growth of the roots in Eucalyptus compared to Melaleuca species”
Claim · model-written summary
The relative rate of biomass accumulation was positively correlated with plant N concentration in both Melaleuca and Eucalyptus.
Verbatim
e0“the relative rate of biomass accumulation was positively correlated with the N concentration of the plant in both genera studied, the associations were stronger and regression coefficients were higher in Eucalyptus than in Melaleuca”
Claim · model-written summary
The association of biomass accumulation rate with N concentration was stronger, with higher regression coefficients, in Eucalyptus than in Melaleuca.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the relative rate of biomass accumulation was positively correlated with the N concentration of the plant in both genera studied, the associations were stronger and regression coefficients were higher in Eucalyptus than in Melaleuca”
Claim · model-written summary
Total plant N content correlated more strongly with N absorption per unit root weight than with root weight.
Not reportedTaxon
Verbatim
e0“The total N content in the plant exhibited a stronger correlation with N absorption per unit root weight than with the root weight”
Claim · model-written summary
Melaleuca species are inferred to be more resistant than Eucalyptus to N-deficiency owing to higher root N uptake ability, higher source activity (photosynthetic rate or leaf area) and more efficient N utilization at low N.
- Treatment
- N-deficiencye0
- Outcome
- more resistant than Eucalyptus to N-deficiencye0
- Qualifier
- a higher ability of N uptake by rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Melaleuca species are more resistant than Eucalyptus to N-deficiency owing to the maintenance of (1) a higher ability of N uptake by roots, (2) higher source activity represented by either the photosynthetic rate or the leaf area, and (3) more efficient N utilization of the source activity at a low N level in the growth medium”
The same questions in other papers
nitrogen · growth · EucalyptusPositive and negative results
6 papers in the same direction as this paper · 4 in the opposite direction
This paper is about lacking the nutrient, so it counts the other way round here.
- negative
- negative
- no effect
7 papers more in this group
See all 11 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.