Growth and Energy Use Efficiency of Grafted Tomato Transplants as Affected by LED Light Quality and Photon Flux Density

Jianfeng Zheng, Peidian Gan, Fang Ji, Dongxian He and Po Yang
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Jianfeng Zheng: Key Laboratory of Agricultural Engineering in Structure and Environment, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100083, China
Peidian Gan: Key Laboratory of Agricultural Engineering in Structure and Environment, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100083, China
Fang Ji: Key Laboratory of Agricultural Engineering in Structure and Environment, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100083, China
Dongxian He: Key Laboratory of Agricultural Engineering in Structure and Environment, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing 100083, China
Po Yang: Beijing Lighting Valley Technology Company, Beijing 100083, China

Agriculture, 2021, vol. 11, issue 9, 1-14

Abstract: This study was conducted to compare the effects of broad spectrum during the whole seedling period and photon flux density (PFD) in the healing stage on the growth and energy use efficiency of grafted tomato ( Lycopersicon esculentum Mill.) transplants in a plant factory. Fluorescent lights, white LED lights, and white plus red LED lights were applied at the growth processes of grafted tomato transplants from germination of rootstock and scion to post-grafting. Three levels of PFD (50, 100, 150 μmol m −2 s −1 ) were set in the healing stage under each kind of light quality. The results indicated that the growth and quality of grafted tomato transplants under different broad spectrums were influenced by the ratio of red to blue light (R/B ratio) and the ratio of red to far-red light (R/FR ratio). A higher R/B ratio was beneficial to total dry matter accumulation, but excessive red light had a negative effect on the root to shoot ratio and the seedling quality index. The higher blue light and R/FR ratio suppressed stem extension synergistically. The LED lights had good abilities to promote plant compactness and leaf thickness in comparison with fluorescent lights. The plant compactness and leaf thickness increased with the increase in daily light integral in the healing stage within a range from 2.5 to 7.5 mol m −2 d −1 (PFD, 50 to 150 μmol m −2 s −1 ). Compared to fluorescent lights, the LED lights showed more than 110% electrical energy saving for lighting during the whole seedling period. Higher PFD in the healing stage did not significantly increase the consumption of electric power for lighting. White plus red LED lights with an R/B ratio of 1.2 and R/FR ratio of 16 were suggested to replace fluorescent lights for grafted tomato transplants production considering the high quality of transplants and electrical energy saving, and PFD in the healing stage was recommended to be set to 150 μmol m −2 s −1 .

Keywords: broad spectrum; white plus red LED; red to blue ratio; daily light integral; photosynthetic capacity; seedling quality (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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