Abstract
Sunburn is a physiological disorder that reduces grape quality and vineyard yield. It is the result of excessive sunlight and high temperatures. As climate change continues to increase air temperatures, reports of sunburn damage in vineyards worldwide are becoming more frequent. Grapes produce secondary metabolites (carotenoids, polyphenols and aroma compounds) to counter photooxidative stress and acclimate to higher radiation environments. This study evaluated changes in these compounds in during ripening when grapes were exposed post-flowering (ED) and at véraison (LD), and compared them to a nondefoliated control (ND). ND contained more α-terpineol and violaxanthin, and the defoliated treatments contained more zeaxanthin, β-carotene, C6 compounds and flavonoids. ED berries adapted better to higher-light environments, displayed larger changes in secondary metabolite concentrations and lower levels of sunburn damage than LD berries did. The composition of berries with increasing sunburn damage was evaluated for the first time. Berries with no damage had the lowest concentrations of flavonoids and oxidized glutathione, and the highest concentrations of chlorophyll and α-terpineol. As damage increased, destruction of photosynthetic pigments, increase in polyphenols and loss of aroma compounds were evidenced. A significant effect of temperature and developmental stage on grape composition was also observed. This study provides a holistic overview of changes in secondary metabolites experienced by grape berries when exposed to excessive light, how these vary along development and how they affect sunburn incidence.
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Claims 12
Claim · model-written summary
Defoliated treatments had more zeaxanthin and β-carotene than the nondefoliated control.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e1“compared them to a nondefoliated control (ND)”
e3“the defoliated treatments contained more zeaxanthin, β-carotene, C6 compounds and flavonoids”
Claim · model-written summary
Defoliated treatments had more C6 compounds and flavonoids than the nondefoliated control.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e1“compared them to a nondefoliated control (ND)”
e3“the defoliated treatments contained more zeaxanthin, β-carotene, C6 compounds and flavonoids”
Claim · model-written summary
The nondefoliated control had more α-terpineol and violaxanthin than the defoliated treatments.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e1“compared them to a nondefoliated control (ND)”
e2“ND contained more α-terpineol and violaxanthin”
e3“the defoliated treatments contained more zeaxanthin, β-carotene, C6 compounds and flavonoids”
Claim · model-written summary
Berries exposed post-flowering adapted better to higher-light environments than berries exposed at véraison.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e0“grapes were exposed post-flowering (ED) and at véraison (LD)”
e4“ED berries adapted better to higher-light environments”
Claim · model-written summary
Berries exposed post-flowering displayed larger changes in secondary metabolite concentrations than berries exposed at véraison.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e0“grapes were exposed post-flowering (ED) and at véraison (LD)”
e5“displayed larger changes in secondary metabolite concentrations”
Claim · model-written summary
Berries exposed post-flowering had lower levels of sunburn damage than berries exposed at véraison.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e0“grapes were exposed post-flowering (ED) and at véraison (LD)”
e6“lower levels of sunburn damage than LD berries did”
Claim · model-written summary
Berries with no damage had the lowest concentrations of flavonoids and oxidized glutathione.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e7“Berries with no damage had the lowest concentrations of flavonoids and oxidized glutathione”
Claim · model-written summary
Berries with no damage had the highest concentrations of chlorophyll and α-terpineol.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e7“Berries with no damage had the lowest concentrations of flavonoids and oxidized glutathione”
e2“the highest concentrations of chlorophyll and α-terpineol”
Claim · model-written summary
As sunburn damage increased, photosynthetic pigments were destroyed in grape berries.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e3“As damage increased, destruction of photosynthetic pigments, increase in polyphenols and loss of aroma compounds were evidenced”
Claim · model-written summary
As sunburn damage increased, polyphenols increased in grape berries.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e3“As damage increased, destruction of photosynthetic pigments, increase in polyphenols and loss of aroma compounds were evidenced”
Claim · model-written summary
As sunburn damage increased, aroma compounds were lost in grape berries.
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e3“As damage increased, destruction of photosynthetic pigments, increase in polyphenols and loss of aroma compounds were evidenced”
Claim · model-written summary
Temperature and developmental stage had a significant effect on grape composition.
Not reportedDirection
Verbatim
t0“Protect Grapes from Excessive Light and Sunburn Damage”
e4“A significant effect of temperature and developmental stage on grape composition was also observed”
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