Abstract
Greater variability in weather patterns and later spring frosts equate to poor winter hardiness, premature spring budbreak, and greater susceptibility to low-temperature damage and concomitant deicing salt application. A field trial was undertaken to determine the influence of a range of commercially available calcium fertilizers applied as foliar sprays on the freezing and salinity tolerance of two tree species, evergreen oak (Quercus ilex L.) and apple (Malus cv. ‘Golden Crown’). In all cases, application of calcium sprays increased twig, leaf, and root freezing and salt tolerance of both species as measured by leaf chlorophyll fluorescence and tissue electrolyte leakage bioassays. In the case of apple, a hardiness gain of 4.3°C (7.74°F) was recorded in twig tissue. In the case of evergreen oak, a hardiness gain of 2.1°C (3.78°F) was recorded in leaf tissue. After a –5°C (23°F) (apple) and –6.5°C (20°F) (evergreen oak) freezing stress, root electrolyte leakage values as a measure of cell membrane structural damage were 16% to 27% less in calcium-treated trees compared with noncalcium-treated controls. The salt concentration needed to cause 50% reductions in leaf chlorophyll fluorescence as a measure of photosynthetic efficiency rose by 0.2% to 1.2% in calcium-fertilized trees indicating a positive influence of calcium on enhancing leaf tissue tolerance to salt damage. Differences in the magnitude of freezing and salinity tolerance gained were noticeable between the calcium products used. In general, calcium hydroxide, calcium nitrate borate, and calcium metalosate improved twig, leaf, and root freezing and salt tolerance in both tree species to a greater degree than calcium chloride, calcium sulphate, calcium nitrate, and a calcium–magnesium complex. A significant correlation existed between increased freezing tolerance and internal tissue calcium content. Results of this study indicate that calcium sprays during late summer and fall can increase the freezing and salinity tolerance of evergreen oak and apple during the winter. This should be considered noteworthy for individuals involved in the management of trees in areas subject to subzero temperature fluctuations and/or concomitant applications of deicing salts in the form of sodium chloride.
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Claims 12
Claim · model-written summary
Calcium sprays increased twig, leaf and root freezing and salt tolerance in evergreen oak.
- Taxon
- evergreen oakt0
- Treatment
- calcium sprayse0
- Outcome
- twig, leaf, and root freezing and salt tolerancee0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“application of calcium sprays increased twig, leaf, and root freezing and salt tolerance of both species”
t0“evergreen oak”
Claim · model-written summary
Calcium sprays increased twig, leaf and root freezing and salt tolerance in apple.
- Taxon
- apple
Malus domesticat0 - Treatment
- calcium sprayse0
- Outcome
- twig, leaf, and root freezing and salt tolerancee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“application of calcium sprays increased twig, leaf, and root freezing and salt tolerance of both species”
t0“apple”
Claim · model-written summary
Apple twig tissue gained 4.3°C in hardiness.
- Taxon
- appleMalus domesticae0
- Organ / stage
- twig tissuee0
- Outcome
- hardiness gaine0
- Direction
- gaine0
- Value
- 4.3°C (7.74°F)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the case of apple, a hardiness gain of 4.3°C (7.74°F) was recorded in twig tissue”
Claim · model-written summary
Evergreen oak leaf tissue gained 2.1°C in hardiness.
Verbatim
e0“In the case of evergreen oak, a hardiness gain of 2.1°C (3.78°F) was recorded in leaf tissue”
Claim · model-written summary
After −5°C freezing, calcium-treated apple roots leaked 16% to 27% less electrolyte than controls.
- Taxon
- appleMalus domesticae0
- Treatment
- calcium-treatede0
- Outcome
- root electrolyte leakage valuese0
- Direction
- lesse0
- Value
- 16% to 27%e0
- Qualifier
- –5°C (23°F)e0
- Comparator
- noncalcium-treated controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After a –5°C (23°F) (apple) and –6.5°C (20°F) (evergreen oak) freezing stress, root electrolyte leakage values as a measure of cell membrane structural damage were 16% to 27% less in calcium-treated trees compared with noncalcium-treated controls”
Claim · model-written summary
After −6.5°C freezing, calcium-treated evergreen oak roots leaked 16% to 27% less electrolyte than controls.
Verbatim
e0“After a –5°C (23°F) (apple) and –6.5°C (20°F) (evergreen oak) freezing stress, root electrolyte leakage values as a measure of cell membrane structural damage were 16% to 27% less in calcium-treated trees compared with noncalcium-treated controls”
Claim · model-written summary
Calcium fertilization raised the salt concentration required for 50% reduction in leaf chlorophyll fluorescence by 0.2% to 1.2% in both trees.
- Taxon
- Evergreen Oak and Applet0
- Treatment
- calcium-fertilizede0
- Outcome
- salt concentration needed to cause 50% reductions in leaf chlorophyll fluorescencee0
- Direction
- rosee0
- Value
- 0.2% to 1.2%e0
Not reportedComparator
Verbatim
e0“The salt concentration needed to cause 50% reductions in leaf chlorophyll fluorescence as a measure of photosynthetic efficiency rose by 0.2% to 1.2% in calcium-fertilized trees”
t0“Evergreen Oak and Apple”
Claim · model-written summary
Calcium hydroxide improved freezing and salt tolerance more than the less effective calcium products.
Verbatim
e0“calcium hydroxide, calcium nitrate borate, and calcium metalosate improved twig, leaf, and root freezing and salt tolerance in both tree species to a greater degree than calcium chloride, calcium sulphate, calcium nitrate, and a calcium–magnesium complex”
t0“Evergreen Oak and Apple”
Claim · model-written summary
Calcium nitrate borate improved freezing and salt tolerance more than the less effective calcium products.
Verbatim
e0“calcium hydroxide, calcium nitrate borate, and calcium metalosate improved twig, leaf, and root freezing and salt tolerance in both tree species to a greater degree than calcium chloride, calcium sulphate, calcium nitrate, and a calcium–magnesium complex”
t0“Evergreen Oak and Apple”
Claim · model-written summary
Calcium metalosate improved freezing and salt tolerance more than the less effective calcium products.
Verbatim
e0“calcium hydroxide, calcium nitrate borate, and calcium metalosate improved twig, leaf, and root freezing and salt tolerance in both tree species to a greater degree than calcium chloride, calcium sulphate, calcium nitrate, and a calcium–magnesium complex”
t0“Evergreen Oak and Apple”
Claim · model-written summary
Freezing tolerance was significantly correlated with internal tissue calcium content.
Verbatim
e0“A significant correlation existed between increased freezing tolerance and internal tissue calcium content”
t0“Evergreen Oak and Apple”
Claim · model-written summary
The authors advised considering late-summer and fall calcium sprays for trees exposed to freezing and deicing salts.
Verbatim
e0“calcium sprays during late summer and fall can increase the freezing and salinity tolerance of evergreen oak and apple during the winter”
The same questions in other papers
application · tolerance: abiotic · Malus domestica (apple)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
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.