Chen Lingyan, Tarin Muhammad Waqqas Khan, Huo Heqiang, Zheng Yushan, Chen Jianjun
College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
Mid-Florida Research Education Center and Environmental Horticulture Department, Institute of Food and Agricultural Sciences, University of Florida, Apopka, FL 32703, USA.
Plants (Basel). 2021 Apr 23;10(5):857. doi: 10.3390/plants10050857.
Light is an essential energy source for plant photosynthesis, although it can also be a stress-causing element. Therefore, the current research was aimed to compare photosynthetic responses of × 'Red' leaves at different positions (bottom old leaf, 1; center mature leaf, 2; top expanded leaf, 3) established under three photosynthetic photon flux densities (PPFDs): 550 μmol·m·s as high (H), 350 μmol·m·s as medium (M), and 255 μmol·m·s as low (L). After six months, all the replicates were relocated to interior rooms with a PPFD of 30 μmol·m·s. There were no significant differences in chlorophyll concentration of the old leaf among treatments, before (Day 0) and after shifting the plants to interior rooms (Day 30). The total chlorophyll concentrations of the mature and top leaves increased significantly. In greenhouse conditions, H and M treatments did not show any significant change for net photosynthetic rate (n) at various leaf positions. However, M2 exhibited an improved n in the interior conditions. Plants grown under M treatment were greener and had bigger leaves compared to other treatments. Our study reveals that × 'Red' photosynthesis responses to different light conditions varied distinctly. However, M treatment can keep the plants looking green by accumulating enough energy for indoor conditions, and middle and lower leaves may be triggered to restore photosynthetic activity under low light or indoor conditions.
光对于植物光合作用而言是必不可少的能量来源，尽管它也可能成为一种造成胁迫的因素。因此，当前的研究旨在比较‘Red’杂交种不同位置叶片（底部老叶，1；中部成熟叶，2；顶部展开叶，3）在三种光合光子通量密度（PPFD）条件下的光合响应：550 μmol·m·s为高光强（H）、350 μmol·m·s为中光强（M）、255 μmol·m·s为低光强（L）。六个月后，所有重复样本被转移至光合光子通量密度为30 μmol·m·s的室内环境。在将植株转移至室内环境之前（第0天）以及转移之后（第30天），各处理下老叶的叶绿素浓度均无显著差异。成熟叶和顶部叶片的总叶绿素浓度显著增加。在温室条件下，H处理和M处理在不同叶位的净光合速率（n）均未表现出任何显著变化。然而，在室内环境下，M2处理的净光合速率有所提高。与其他处理相比，M处理下生长的植株更绿且叶片更大。我们的研究表明，‘Red’杂交种对不同光照条件的光合响应差异显著。然而，M处理能够通过积累足够的能量以适应室内条件，从而使植株保持绿色外观，并且在弱光或室内条件下，中下部叶片可能会被激发恢复光合活性。
