Abstract
This study documents changes in yield, growth, soil salinity (ECe) and leaf sodium (Na) and chlorine (Cl) concentrations in mature Valencia orange [Citrus sinensis (L.Osbeck)] trees on sweet orange (Citrus sinensis) rootstock in response to increased levels of Na and Cl in irrigation water. Four levels of salt, ranging from the river-water control (0.44 dS/m) to 2.50 dS/m, were applied over a 9-year period through an under-tree microsprinkler system to trees in the Sunraysia area of the Murray Valley in south-eastern Australia. A salt-balance model showed that evapotranspiration was reduced by salinity, whereas leaching fractions increased from an average 24% in the control to 51% in the most saline treatment. The high leaching fractions were achieved as a result of freely draining soils and good irrigation management, and allowed us to maintain low to moderate levels of soil salinity throughout the trial and minimised the effect of salt treatment on fruit yield. Soil salinity increased almost linearly in response to irrigation-water salinity during the first year, and fluctuated seasonally thereafter; however, very few readings exceeded 3 dS/m, even in the highest treatments. By contrast, leaf Na and Cl concentrations in the highest salt treatment continued to increase over the first 4 years. The relationship between yield and soil salinity was extremely weak, but yield did decrease as foliar concentrations of Na and Cl increased: in Year 9, leaf Na in the highest treatment relative to the control was associated with a predicted reduction of 17% in yield and 59% in annual trunk-diameter growth.
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Claims 14
Claim · model-written summary
A salt-balance model showed reduced evapotranspiration under salinity.
Verbatim
e0“A salt-balance model showed that evapotranspiration was reduced by salinity”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Leaching fractions rose from 24% in controls to 51% in the saltiest treatment.
Verbatim
e0“leaching fractions increased from an average 24% in the control to 51% in the most saline treatment”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Freely draining soils and irrigation management maintained low to moderate soil salinity.
Verbatim
e0“The high leaching fractions were achieved as a result of freely draining soils and good irrigation management, and allowed us to maintain low to moderate levels of soil salinity throughout the trial and minimised the effect of salt treatment on fruit yield.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
High leaching fractions minimized the salt treatment effect on fruit yield.
Verbatim
e0“The high leaching fractions were achieved as a result of freely draining soils and good irrigation management, and allowed us to maintain low to moderate levels of soil salinity throughout the trial and minimised the effect of salt treatment on fruit yield.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Soil salinity increased nearly linearly with irrigation-water salinity in year one.
Verbatim
e0“Soil salinity increased almost linearly in response to irrigation-water salinity during the first year”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Soil salinity fluctuated seasonally afterward.
Verbatim
e0“and fluctuated seasonally thereafter; however, very few readings exceeded 3 dS/m, even in the highest treatments.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Very few soil salinity readings exceeded 3 dS/m.
Verbatim
e0“very few readings exceeded 3 dS/m, even in the highest treatments.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
leaf Na increased during the first four years under the highest salt treatment.
- Taxon
- oranget0
- Treatment
- highest salt treatmente0
- Outcome
- leaf Nae0
- Direction
- increasee0
- Qualifier
- first 4 yearse0
Not reportedComparator
Verbatim
e0“leaf Na and Cl concentrations in the highest salt treatment continued to increase over the first 4 years.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Cl concentrations increased during the first four years under the highest salt treatment.
- Taxon
- oranget0
- Treatment
- highest salt treatmente0
- Outcome
- Cl concentrationse0
- Direction
- increasee0
- Qualifier
- first 4 yearse0
Not reportedComparator
Verbatim
e0“leaf Na and Cl concentrations in the highest salt treatment continued to increase over the first 4 years.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Yield was very weakly related to soil salinity.
Not reportedDirection
Verbatim
e0“The relationship between yield and soil salinity was extremely weak”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Yield fell as foliar Na concentration increased.
Verbatim
e0“yield did decrease as foliar concentrations of Na and Cl increased”
t0“‘Valencia’ orange trees”
Claim · model-written summary
Yield fell as foliar Cl concentration increased.
Verbatim
e0“yield did decrease as foliar concentrations of Na and Cl increased”
t0“‘Valencia’ orange trees”
Claim · model-written summary
In year nine, leaf Na was associated with a predicted 17% reduction in yield.
Verbatim
e0“in Year 9, leaf Na in the highest treatment relative to the control was associated with a predicted reduction of 17% in yield and 59% in annual trunk-diameter growth.”
t0“‘Valencia’ orange trees”
Claim · model-written summary
In year nine, leaf Na was associated with a predicted 59% reduction in annual trunk-diameter growth.
Verbatim
e0“in Year 9, leaf Na in the highest treatment relative to the control was associated with a predicted reduction of 17% in yield and 59% in annual trunk-diameter growth.”
t0“‘Valencia’ orange trees”