Abstract
Abstract Key message Covering young ‘Hass’ trees with Silver 60% shading nets during cold winters mitigates frost damage and improves tree performance, apparently through a mechanism other than increasing nighttime air temperature. Abstract Avocado is a commercially important subtropical evergreen fruit tree. Severe frost may damage foliage, floral buds, flowers and fruit, thereby reducing avocado crop yield and restricting its geographical distribution and expansion. Shading nets are frequently used to protect agricultural crops from climate-related damage. To determine their ability to mitigate frost damage, Silver 60% shading nets were deployed over young ‘Hass’ trees during two consecutive winters and uncovered trees served as controls. Freezing and chilling temperatures occurred in the experimental orchard during the winter of each year, from December to March, reaching − 2.49 ℃ in January 2022. In the control, 93% of the examined floral buds were severely damaged compared to 4% in the Silver 60% trees. Damage to young vegetative shoots was assessed at 4.35 out of 5 in the control compared to 0.5 out of 5 in the Silver 60% trees. In both years, minimum air temperatures under the Silver 60% shading nets were similar to those of the control. Leaf-level photosynthetic photon flux density was ~ 60% lower under the shading nets. In most measurements, CO 2 -assimilation rate, stomatal conductance, ratio of variable to maximum fluorescence (Fv/Fm) and chlorophyll concentration in the leaves of the Silver 60% trees were higher than, or similar to the controls. Trunk diameter and flowering intensity of the Silver 60% trees were higher than for the control. These results indicate that covering young ‘Hass’ trees with Silver 60% shading nets during cold winters can mitigate frost damage and improve tree performance.
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Claims 8
Claim · model-written summary
Silver 60% shading nets reduced severe floral bud damage: 93% of control floral buds were severely damaged versus 4% under the nets.
- Taxon
- avocado
Persea americanat0 - Treatment
- Silver 60% shading netse2
- Outcome
- floral budse1
- Direction
- decreaseinferrede1
- Value
- 93%e1
- Qualifier
- 4% in the Silver 60% treese1
- Comparator
- uncovered treese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e1“In the control, 93% of the examined floral buds were severely damaged compared to 4% in the Silver 60% trees”
e2“Silver 60% shading nets were deployed over young”
e3“uncovered trees served as controls”
Claim · model-written summary
Silver 60% shading nets reduced damage to young vegetative shoots from 4.35 to 0.5 out of 5.
- Taxon
- avocadoPersea americanat0
- Treatment
- Silver 60% shading netse2
- Outcome
- damage to young vegetative shootse4
- Direction
- decreaseinferrede4
- Value
- 0.5 out of 5e4
- Qualifier
- 4.35 out of 5 in the controle4
- Comparator
- controle4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e2“Silver 60% shading nets were deployed over young”
e4“Damage to young vegetative shoots was assessed at 4.35 out of 5 in the control compared to 0.5 out of 5 in the Silver 60% trees”
Claim · model-written summary
Minimum air temperatures under the Silver 60% shading nets were similar to those of the control in both years.
- Taxon
- avocadoPersea americanat0
- Outcome
- minimum air temperaturese6
- Comparator
- controle6
- Setting
- Silver 60% shading netse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e6“minimum air temperatures under the Silver 60% shading nets were similar to those of the control”
Claim · model-written summary
Leaf-level photosynthetic photon flux density was about 60% lower under the shading nets.
- Taxon
- AvocadoPersea americanae0
- Outcome
- Leaf-level photosynthetic photon flux densitye5
- Direction
- lowere5
- Value
- ~ 60%e5
- Setting
- under the shading netse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Avocado is a commercially important subtropical evergreen fruit tree”
e5“Leaf-level photosynthetic photon flux density was ~ 60% lower under the shading nets”
Claim · model-written summary
In most measurements, CO2 assimilation rate, stomatal conductance and Fv/Fm of Silver 60% trees were higher than or similar to the controls.
- Taxon
- avocadoPersea americanat0
- Treatment
- Silver 60% treese7
- Outcome
- CO 2 -assimilation rate, stomatal conductance, ratio of variable to maximum fluorescence (Fv/Fm)e7
- Direction
- higher than, or similar toe7
- Comparator
- controlse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e7“CO 2 -assimilation rate, stomatal conductance, ratio of variable to maximum fluorescence (Fv/Fm) and chlorophyll concentration in the leaves of the Silver 60% trees were higher than, or similar to the controls”
Claim · model-written summary
In most measurements, chlorophyll concentration in leaves of Silver 60% trees was higher than or similar to the controls.
- Taxon
- avocadoPersea americanat0
- Treatment
- Silver 60% treese7
- Outcome
- chlorophyll concentratione7
- Direction
- higher than, or similar toe7
- Comparator
- controlse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e7“CO 2 -assimilation rate, stomatal conductance, ratio of variable to maximum fluorescence (Fv/Fm) and chlorophyll concentration in the leaves of the Silver 60% trees were higher than, or similar to the controls”
Claim · model-written summary
Trunk diameter and flowering intensity of Silver 60% trees were higher than those of the control.
- Taxon
- avocadoPersea americanat0
- Treatment
- Silver 60% treese1
- Outcome
- Trunk diameter and flowering intensitye1
- Direction
- highere1
- Comparator
- controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
e1“Trunk diameter and flowering intensity of the Silver 60% trees were higher than for the control”
Claim · model-written summary
Shading nets may mitigate frost damage through a mechanism other than raising nighttime air temperature.
- Taxon
- avocadoPersea americanat0
- Outcome
- frost damaget1
- Qualifier
- apparently through a mechanism other than increasing nighttime air temperaturee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Covering young avocado”
t1“mitigates frost damage”
e1“apparently through a mechanism other than increasing nighttime air temperature”