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Article

Light Quality Affected the Growth and Root Organic Carbon and Autotoxin Secretions of Hydroponic Lettuce

by 1,2, 1,2, 1,2,*, 1,2, 1,2 and 1,2
1
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
2
Key Lab of Energy Conservation and Waste Management of Agricultural Structures, Ministry of Agriculture and Rural Affairs, Beijing 100081, China
*
Author to whom correspondence should be addressed.
Plants 2020, 9(11), 1542; https://doi.org/10.3390/plants9111542
Received: 6 October 2020 / Revised: 6 November 2020 / Accepted: 9 November 2020 / Published: 11 November 2020
Light is a crucial environmental signal and photosynthetic energy for plant growth, development, and primary and secondary metabolism. To explore the effects of light quality on the growth and root exudates of hydroponic lettuce (Lactuca sativa L.), white LED (W, control) and four the mixtures of red (R) and blue (B) LED with different R/B light intensity ratios (R/B = 2, 2R1B; R/B = 3, 3R1B; R/B = 4, 4R1B; and R/B = 8, 8R1B) were designed. The results showed that the biomass of lettuce under 8R1B and W treatments was higher than that under other light quality treatments. The photosynthetic rate (Pn) under red and blue light was significantly higher than that of white light. Total root length, root surface area, and root volume were the highest under 8R1B. 4R1B treatment significant increased root activity by 68.6% compared with W. In addition, total organic carbon (TOC) content, TOC content/shoot dry weight, TOC content/root dry weight, and TOC content/root surface area were the highest under 4R1B. Moreover, 8R1B treatment reduced the concentration of benzoic acid and salicylic acid, and the secretion ability of benzoic acid and salicylic acid by per unit root surface area and accumulation by per unit shoot dry weight. In addition, 2R1B and 3R1B reduced the secretion ability of gallic acid and tannic acid by per unit root surface area and accumulation by per unit shoot dry weight. In conclusion, this study showed that the secretion of autotoxins could be reduced through the mediation of red and blue light composition of LEDs in a plant factory. In terms of autotoxin secretion reduction efficiency and yield performance of lettuce, 8R1B light regime is recommended for practical use. View Full-Text
Keywords: botany; plant factory; LED; light quality; autotoxicity botany; plant factory; LED; light quality; autotoxicity
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MDPI and ACS Style

Zhou, C.; Zhang, Y.; Liu, W.; Zha, L.; Shao, M.; Li, B. Light Quality Affected the Growth and Root Organic Carbon and Autotoxin Secretions of Hydroponic Lettuce. Plants 2020, 9, 1542. https://doi.org/10.3390/plants9111542

AMA Style

Zhou C, Zhang Y, Liu W, Zha L, Shao M, Li B. Light Quality Affected the Growth and Root Organic Carbon and Autotoxin Secretions of Hydroponic Lettuce. Plants. 2020; 9(11):1542. https://doi.org/10.3390/plants9111542

Chicago/Turabian Style

Zhou, Chengbo, Yubin Zhang, Wenke Liu, Lingyan Zha, Mingjie Shao, and Baoshi Li. 2020. "Light Quality Affected the Growth and Root Organic Carbon and Autotoxin Secretions of Hydroponic Lettuce" Plants 9, no. 11: 1542. https://doi.org/10.3390/plants9111542

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