Lu Tao, Song Yangfan, Yu Hongjun, Li Qiang, Xu Jingcheng, Qin Yong, Zhang Guanhua, Liu Yuhong, Jiang Weijie
Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
College of Horticulture, Xinjiang Agricultural University, Ürümqi, China.
Front Plant Sci. 2022 Apr 12;13:831314. doi: 10.3389/fpls.2022.831314. eCollection 2022.
Adverse environmental conditions, such as low temperature (LT), greatly limit the growth and production of tomato. Recently, light-emitting diodes (LEDs) with specific spectra have been increasingly used in horticultural production facilities. The chosen spectrum can affect plant growth, development, and resistance, but the physiological regulatory mechanisms are largely unknown. In this study, we investigated the effects of LED light supplementation (W:B = 2:1, light intensity of 100 μmol⋅m⋅s, for 4 h/day from 9:00 to 13:00) from above and below the canopy on tomato resistance under sub-LT stress (15/8°C). The results showed that supplemental lighting from underneath the canopy (USL) promoted the growth of tomato seedlings, as the plant height, stem diameter, root activity, and plant biomass were significantly higher than those under LT. The activity of the photochemical reaction center was enhanced because of the increase in the maximal photochemical efficiency (F /F ) and photochemical quenching (qP), which distributed more photosynthetic energy to the photochemical reactions and promoted photosynthetic performance [the maximum net photosynthetic rate () was improved]. USL also advanced the degree of stomatal opening, thus facilitating carbon assimilation under LT. Additionally, the relative conductivity (RC) and malondialdehyde (MDA) content were decreased, while the soluble protein content and superoxide dismutase (SOD) activity were increased with the application of USL under LT, thereby causing a reduction in membrane lipid peroxidation and alleviation of stress damage. These results suggest that light supplementation from underneath the canopy improves the cold resistance of tomato seedlings mainly by alleviating the degree of photoinhibition on photosystems, improving the activity of the photochemical reaction center, and enhancing the activities of antioxidant enzymes, thereby promoting the growth and stress resistance of tomato plants.
不利的环境条件，如低温（LT），极大地限制了番茄的生长和产量。近年来，具有特定光谱的发光二极管（LED）在园艺生产设施中得到了越来越广泛的应用。所选光谱会影响植物的生长、发育和抗性，但其生理调节机制在很大程度上尚不清楚。在本研究中，我们调查了在亚低温胁迫（15/8°C）下，从冠层上方和下方进行LED补光（光质比W:B = 2:1，光强为100 μmol⋅m⋅s，每天9:00至13:00补光4小时）对番茄抗性的影响。结果表明，冠层下方补光（USL）促进了番茄幼苗的生长，其株高、茎粗、根系活力和植株生物量均显著高于低温处理下的植株。由于最大光化学效率（F /F ）和光化学猝灭（qP）的增加，光化学反应中心的活性增强，这将更多的光合能量分配到光化学反应中，促进了光合性能[最大净光合速率（）提高]。USL还提高了气孔开放程度，从而促进了低温下的碳同化。此外，在低温处理下，施加USL可降低相对电导率（RC）和丙二醛（MDA）含量，同时增加可溶性蛋白含量和超氧化物歧化酶（SOD）活性，从而减少膜脂过氧化并减轻胁迫损伤。这些结果表明，冠层下方补光主要通过减轻光系统的光抑制程度、提高光化学反应中心的活性以及增强抗氧化酶的活性来提高番茄幼苗的抗冷性，从而促进番茄植株的生长和抗逆性。
