Abstract
As a promising environmental protection technology, the application of ultraviolet B irradiation in vegetable production has been widely considered. However, the effect of UVB irradiation varies with different plant varieties. In this study, we investigated the effects of two UVB intensities (0.7, 1.4 W m−2) on the accumulation of phenolics and flavonoids, and antioxidant activity of green-leaf and red-leaf lettuce (Lactuca sativa L.) 7 days prior to harvest. The results indicated that short-term (within 2 days) UVB treatment could promote the increase in total chlorophyll content of red-leaf lettuce and green-leaf lettuce, which increased by 49.8% and 20.6% compared with day zero, respectively, and was beneficial to the synthesis of carotenoids of red-leaf lettuce. Extending UVB exposure time significantly decreased chlorophyll a/b value of green-leaf lettuce from 0.92 to 0.63, and simultaneously increased the accumulation of antioxidant substances such as flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce, 84.1% and 110.9% of green-leaf lettuce. In contrast, red-leaf lettuce had a higher accumulation level of secondary metabolites, faster scavenging rate of free radicals, and stronger ability to resist UVB stress. Our results suggest that supplementation of low-dose UVB radiance prior to harvest can improve the secondary metabolite content and antioxidant activity of the two kinds of lettuce. This research provided a theoretical basis for improving lettuce quality by pre-harvest UVB treatment in controlled environmental agriculture.
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Claims 11
Claim · model-written summary
Short UVB treatment increased total chlorophyll in red-leaf lettuce by 49.8% from day zero.
- Taxon
- lettuce
Lactuca sativae0 - Material
- red-leaf lettucee0
- Treatment
- UVB treatmente0
- Outcome
- total chlorophyll contente0
- Direction
- increasede0
- Value
- 49.8%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“short-term (within 2 days) UVB treatment could promote the increase in total chlorophyll content of red-leaf lettuce and green-leaf lettuce, which increased by 49.8% and 20.6% compared with day zero”
Claim · model-written summary
Short UVB treatment increased total chlorophyll in green-leaf lettuce by 20.6% from day zero.
- Taxon
- lettuceLactuca sativae0
- Material
- green-leaf lettucee0
- Treatment
- UVB treatmente0
- Outcome
- total chlorophyll contente0
- Direction
- increasede0
- Value
- 20.6%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“short-term (within 2 days) UVB treatment could promote the increase in total chlorophyll content of red-leaf lettuce and green-leaf lettuce, which increased by 49.8% and 20.6% compared with day zero”
Claim · model-written summary
Short UVB treatment benefited carotenoid synthesis in red-leaf lettuce.
- Taxon
- lettuceLactuca sativae0
- Material
- red-leaf lettucee0
- Treatment
- UVB treatmente0
- Outcome
- synthesis of carotenoidse0
- Direction
- beneficiale0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UVB treatment could promote the increase in total chlorophyll content of red-leaf lettuce and green-leaf lettuce, which increased by 49.8% and 20.6% compared with day zero, respectively, and was beneficial to the synthesis of carotenoids of red-leaf lettuce”
Claim · model-written summary
Longer UVB exposure decreased the chlorophyll a/b value of green-leaf lettuce from 0.92 to 0.63.
- Taxon
- lettuceLactuca sativae0
- Material
- green-leaf lettucee0
- Treatment
- Extending UVB exposure timee0
- Outcome
- chlorophyll a/b valuee0
- Direction
- decreasede0
- Value
- 0.92 to 0.63e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Extending UVB exposure time significantly decreased chlorophyll a/b value of green-leaf lettuce from 0.92 to 0.63”
Claim · model-written summary
UVB-0.7 increased red-leaf lettuce flavonoids by 90.0% from day zero.
- Taxon
- lettuceLactuca sativae0
- Material
- red-leaf lettucee0
- Treatment
- UVB-0.7e0
- Outcome
- flavonoidse0
- Direction
- increasede0
- Value
- 90.0%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce”
Claim · model-written summary
UVB-1.4 increased red-leaf lettuce flavonoids by 183.4% from day zero.
- Taxon
- lettuceLactuca sativae0
- Material
- red-leaf lettucee0
- Treatment
- UVB-1.4e0
- Outcome
- flavonoidse0
- Direction
- increasede0
- Value
- 183.4%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce”
Claim · model-written summary
UVB-0.7 increased green-leaf lettuce flavonoids by 84.1% from day zero.
- Taxon
- lettuceLactuca sativae0
- Material
- green-leaf lettucee0
- Treatment
- UVB-0.7e0
- Outcome
- flavonoidse0
- Direction
- increasede0
- Value
- 84.1%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce, 84.1% and 110.9% of green-leaf lettuce”
Claim · model-written summary
UVB-1.4 increased green-leaf lettuce flavonoids by 110.9% from day zero.
- Taxon
- lettuceLactuca sativae0
- Material
- green-leaf lettucee0
- Treatment
- UVB-1.4e0
- Outcome
- flavonoidse0
- Direction
- increasede0
- Value
- 110.9%e0
- Comparator
- day zeroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce, 84.1% and 110.9% of green-leaf lettuce”
Claim · model-written summary
Red-leaf lettuce accumulated more secondary metabolites than green-leaf lettuce.
Verbatim
e0“red-leaf lettuce had a higher accumulation level of secondary metabolites”
Claim · model-written summary
Red-leaf lettuce scavenged free radicals faster than green-leaf lettuce.
Verbatim
e0“red-leaf lettuce had a higher accumulation level of secondary metabolites, faster scavenging rate of free radicals”
Claim · model-written summary
Red-leaf lettuce resisted UVB stress more strongly than green-leaf lettuce.
Verbatim
e0“red-leaf lettuce had a higher accumulation level of secondary metabolites, faster scavenging rate of free radicals, and stronger ability to resist UVB stress”
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