Photosynthetic Efficiency and Anatomical Structure of Pepper Leaf (Capsicum annuum L.) Transplants Grown under High-Pressure Sodium (HPS) and Light-Emitting Diode (LED) Supplementary Lighting Systems

Abstract

The aim of this study was to evaluate the effects of various supplemental greenhouse lighting systems, i.e., high-pressure sodium lamps and mixtures of red and blue light-emitting diodes, on the photochemical efficiency, anatomical leaf structure, and growth of the two pepper cultivars. The intensity levels of the photosynthetically active radiation were the same for both light treatments. In this study, the relative chlorophyll content was measured. Additionally, certain parameters of chlorophyll a fluorescence were measured under ambient light or after dark adaptation. The obtained results showed that the application of light-emitting diodes (LEDs) as supplemental lighting positively affected the anatomical leaf characteristics and plant growth. The leaves of both pepper cultivars were thicker and had larger palisade parenchyma cells under LED supplemental lighting compared to leaves grown under high-pressure sodium (HPS) lamps. Moreover, the mesophyll cells of seedlings grown under LEDs contained more chloroplasts than those growing under HPS lighting. The chlorophyll a fluorescence measurements of pepper seedlings grown under LEDs showed significant increases in photosynthetic apparatus performance index (PI) values compared to plants grown under HPS lamps; however, the values for this index were higher in cv. ‘Aifos’ as compared to cv. ‘Palermo’. We recommend that supplemental lighting systems are applied with caution, as their performance appears to depend not only on the light spectrum but also on the cultivar.

Modulations in Chlorophyll a Fluorescence Based on Intensity and Spectral Variations of Light

“…The synthesis pathway for chlorophyll b is more IR-resistant, and Chl b predominates in PSII’s external antenna and light-recovery complex. In this case, IR mostly influences chlorophyll content by reducing the quantity and size of chloroplasts [ 84 , 85 ]. In addition, NPQ fluctuates in response to different IR dosages.…”

“…F V /F M , which indicates photosynthetic performance, is usually IR-resistant; however, it varies depending on the electron transport rate. F V /F M can drop or slightly rise during irradiation, depending on the dose and kind of IR [ 84 ].…”

Effect of Photoconversion Coatings for Greenhouses on Electrical Signal-Induced Resistance to Heat Stress of Tomato Plants

“…The coatings used in this work have photoluminescence maxima at 450 and nm, which quite well correspond to the absorption maxima of tomato plants, locate the region of 440 and 675 nm [29]. Stimulating photosynthesis by increasing the pro tion of light in the blue and red regions of the spectrum has been shown in a large num of works [1][2][3][4][5][6]10,11,14]. Such stimulation can be caused both by a direct increase in amount of energy available for photosynthesis and by the adjustment of physiolo processes due to signaling pathways starting from photoreceptors.…”

“…In temperate and polar latitudes, one of the most serious problems is insufficient illumination, in particular at wavelengths used in the course of photosynthetic reactions. This problem can be solved by active backlighting using LEDs or other light sources [1][2][3][4][5][6]. However, this approach requires high economic and energy costs, which leads to an increase in carbon footprint [7].…”

The Combinations of White, Blue, and UV-A Light Provided by Supplementary Light-Emitting Diodes Promoted the Quality of Greenhouse-Grown Cucumber Seedlings

“…Light quality also has significant impacts on the formation and composition of plant organic matter [14,15]. For instance, red light is efficient in driving plant photosynthesis compared with other wavelengths [16]; blue light promoted the synthesis of chlorophyll in cucumber, wheat, and spinach [17,18].…”