Abstract
The aim of the present study was to evaluate the effects of alternating red (660 nm) and blue (460 nm) light on the growth and nutritional quality of two-leaf-color pak choi ( Brassica campestris L. ssp. chinensis var. communis ). Four light treatments (supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours, with a monochromatic light intensity of 100 μmol·m −2 ·s −1 and a cumulative lighting time of 16 hours per day) were conducted in a greenhouse under identical ambient light conditions (90 to 120 μmol·m −2 ·s −1 at 12:00 am ) for 10 days before green- and red-leaf pak choi were harvested. The results showed that the two-leaf-color pak choi receiving alternating red and blue light exhibited more compact canopies and wider leaves than those under the control treatment, which was attributed to the shade avoidance syndrome of plants. The present study indicated that the biomass of green-leaf pak choi was much higher than that of red-leaf pak choi, but the nutritional quality of green-leaf pak choi was lower than that of red-leaf pak choi, and seemingly indicating that the regulation of metabolism for pak choi was species specific under light exposure. The trends of both biomass and the soluble sugar content were highest under the 1-hour treatment. The contents of chlorophyll a and total chlorophyll in both cultivars (green- and red-leaf pak choi) were significantly increased compared with control, without significant differences among the 1-, 2-, and 4-hour treatments, whereas chlorophyll b exhibited no significant difference in any treatment. Alternating red- and blue-light treatment significantly affected the carotenoid content, but different trends in green- and red-leaf pak choi were observed, with the highest contents being detected under the 1-hour and 4-hour treatments, respectively. With increasing time intervals, the highest soluble protein contents in two-leaf-color pak choi were observed in the 4-hour treatment, whereas nitrate contents were significantly decreased in the 4-hour treatment. Compared with 0 hours, the contents of vitamin C, phenolic compounds, flavonoids, and anthocyanins in two-leaf-color pak choi were significantly increased, but no significant differences were observed in vitamin C, phenolic compounds, and flavonoids among the 1-, 2-, and 4-hour treatments, similar to what was found for the anthocyanin content of green-leaf pak choi. However, the content of anthocyanins in red-leaf pak choi gradually increased with increasing time intervals, with the highest content being found in the 4-hour treatment. Supplemental alternating red and blue light slightly increased the antioxidant capacity [1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate and antioxidant power], but no significant differences were observed after 1, 2, and 4 hours of treatment. Taken together, treatment with an interval of 1 hour was the most effective for increasing the biomass of pak choi in this study, but treatment with a 4-hour interval should be considered to enhance the accumulation of health-promoting compounds.
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Claims 18
Claim · model-written summary
Alternating red and blue light gave pak choi more compact canopies and wider leaves than the control.
Verbatim
e1“the two-leaf-color pak choi receiving alternating red and blue light exhibited more compact canopies and wider leaves than those under the control treatment”
e2“supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Green-leaf pak choi had much higher biomass than red-leaf pak choi.
Verbatim
e3“the biomass of green-leaf pak choi was much higher than that of red-leaf pak choi”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Green-leaf pak choi had lower nutritional quality than red-leaf pak choi.
Verbatim
e4“the nutritional quality of green-leaf pak choi was lower than that of red-leaf pak choi”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Biomass and soluble sugar content were highest under the 1-hour light interval treatment.
Verbatim
e5“The trends of both biomass and the soluble sugar content were highest under the 1-hour treatment”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Chlorophyll a and total chlorophyll contents were significantly increased compared with control.
Verbatim
e6“The contents of chlorophyll a and total chlorophyll in both cultivars (green- and red-leaf pak choi) were significantly increased compared with control”
e2“supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Chlorophyll b showed no significant difference under any light treatment.
- Taxon
- pak choit0
- Treatment
- alternating red and blue lighte2
- Outcome
- chlorophyll be7
- Direction
- no significant differencee7
Not reportedComparator
Verbatim
e7“chlorophyll b exhibited no significant difference in any treatment”
e2“supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Carotenoid content was highest under the 1-hour treatment in green-leaf pak choi.
Verbatim
e2“Alternating red- and blue-light treatment significantly affected the carotenoid content, but different trends in green- and red-leaf pak choi were observed”
e3“with the highest contents being detected under the 1-hour and 4-hour treatments, respectively”
Claim · model-written summary
Carotenoid content was highest under the 4-hour treatment in red-leaf pak choi.
Verbatim
e2“Alternating red- and blue-light treatment significantly affected the carotenoid content, but different trends in green- and red-leaf pak choi were observed”
e3“with the highest contents being detected under the 1-hour and 4-hour treatments, respectively”
Claim · model-written summary
Soluble protein content was highest in the 4-hour treatment.
Verbatim
e4“the highest soluble protein contents in two-leaf-color pak choi were observed in the 4-hour treatment”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Nitrate content was significantly decreased in the 4-hour treatment.
Verbatim
e5“in two-leaf-color pak choi were observed in the 4-hour treatment, whereas nitrate contents were significantly decreased in the 4-hour treatment”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Vitamin C, phenolic compounds and flavonoid contents were significantly increased compared with 0 hours.
Verbatim
e6“Compared with 0 hours, the contents of vitamin C, phenolic compounds, flavonoids, and anthocyanins in two-leaf-color pak choi were significantly increased”
e2“supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Anthocyanin content was significantly increased compared with 0 hours.
Verbatim
e6“Compared with 0 hours, the contents of vitamin C, phenolic compounds, flavonoids, and anthocyanins in two-leaf-color pak choi were significantly increased”
e2“supplemental alternating red and blue light with intervals of 0, 1, 2, and 4 hours”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Vitamin C, phenolic compounds and flavonoids showed no significant differences among the 1-, 2- and 4-hour treatments.
Verbatim
e7“no significant differences were observed in vitamin C, phenolic compounds, and flavonoids among the 1-, 2-, and 4-hour treatments”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Anthocyanin content in red-leaf pak choi gradually increased with longer light intervals, highest in the 4-hour treatment.
Verbatim
e0“the content of anthocyanins in red-leaf pak choi gradually increased with increasing time intervals, with the highest content being found in the 4-hour treatment”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Supplemental alternating red and blue light slightly increased antioxidant capacity.
Verbatim
e1“Supplemental alternating red and blue light slightly increased the antioxidant capacity”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Antioxidant capacity showed no significant differences after 1, 2 and 4 hours of treatment.
Verbatim
e2“no significant differences were observed after 1, 2, and 4 hours of treatment”
e1“Supplemental alternating red and blue light slightly increased the antioxidant capacity”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
The more compact canopies and wider leaves under light treatment are attributed to shade avoidance syndrome.
Verbatim
e3“exhibited more compact canopies and wider leaves than those under the control treatment, which was attributed to the shade avoidance syndrome of plants”
t0“Two-leaf-color Pak Choi”
Claim · model-written summary
Treatment with a 4-hour interval should be considered to enhance accumulation of health-promoting compounds in pak choi.
Verbatim
e4“treatment with a 4-hour interval should be considered to enhance the accumulation of health-promoting compounds”
t0“Two-leaf-color Pak Choi”
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