Effect of Red and Blue LED Lights on Morphological and Physiological Characteristics of Hyssop (Hyssopus officinalis L.)

Document Type : Research Article

Authors

F. Esmaeili ¹

H. Bayat ¹

H. Nastari Nasrabadi ²

M.H. Aminifard ¹

¹ Department of Horticulture Science and Engineering, College of Agriculture, University of Birjand, Birjand, Iran

² Department of Horticulture Science and Engineering, Respectively, Faculty of Agriculture and Animal Science, University of Torbat-e Jam, Torbat- e Jam, Khorasan Razavi, Iran.

https://doi.org/10.22067/jhs.2025.90559.1387

Abstract

Light plays a fundamental role in plant growth and development, significantly influencing photosynthesis and overall plant yield. Various light characteristics, including intensity, quality, and duration, have critical effects on plant biological processes. The light spectrum can significantly impact plant metabolism throughout the growth period. The use of LED light not only provides the necessary wavelengths but also reduces energy loss and allows precise control over the photosynthetic photon flux. LED lighting can be utilized to optimize plant growth and yield in greenhouse and growth chamber environments. Blue and red light are the primary wavelengths involved in carbon dioxide fixation and photosynthesis, exerting a significant influence on plant growth (Cosgrove, 1981; Kasajima et al., 2008.( Hyssopus officinalis, a perennial plant belonging to the Lamiaceae family, is well known for its antimicrobial, antioxidant, and anti-inflammatory properties. This study evaluates LED light as an alternative to natural sunlight in controlled environments. Previous research has shown that changes in light quality can significantly affect growth parameters such as plant height, stem length, leaf length and width, leaf area, and fresh and dry biomass. Optimizing light conditions can enhance plant production in closed environments, offering economic and scientific potential for the cultivation of medicinal plants. The objective of this research was to investigate the effects of different LED light spectra on the growth, physiological, and morphological characteristics of Hyssopus officinalis.
 
Materials and Methods
To investigate the growth and physiological characteristics of Hyssopus officinalis, an experiment was conducted using a completely randomized design with three replications and six LED light treatments. The seeds were sourced from Glass Garden Company. The growing medium consisted of a mixture of 40% cocopeat, 40% perlite, and 20% vermiculite to provide optimal conditions for plant growth.  In the growth chamber, the light treatments included white (control), 100% red, 100% blue, red:blue (70:30), red:blue (30:70), and red:blue (50:50). White light served as the control treatment. The LED lamps used in this experiment were 24-watt wall washers with different light spectra, covering wavelengths from 400 to 700 nm. The light intensity was set at 250 ± 10 μmol photons.m⁻².s⁻¹. The photoperiod was maintained at 16 hours of light and 8 hours of darkness, with day and night temperatures of 25°C and 20°C, respectively. Following germination, the plants were irrigated daily with a half-strength Hoagland nutrient solution. Once the plants reached the four-leaf stage, they were supplied with a full-strength Hoagland solution every other day (20 g in 10 liters of distilled water) at a rate of 100 cc per pot .After five months, morphological and physiological parameters were evaluated. Measurements included stem, root, and leaf length; leaf width; leaf area; root volume; internode length; number of lateral branches; fresh and dry weight of roots, stems, and leaves; total plant fresh and dry weight; and chlorophyll a, chlorophyll b, total chlorophyll, and essential oil yield. Data analysis was performed using SAS statistical software, and mean comparisons were conducted using the LSD test at a significance level of p ≤ 0.05.
 
Results and Discussion
The results showed that different light spectra had a significant effect on the growth and physiological characteristics of the hyssop plant at the 5% and 1% probability levels. The highest fresh and dry weight of shoot, root, and total plant was recorded under red light. The highest amounts of chlorophyll a (1.11 mg.g^-1 fresh weight) and chlorophyll b (1.89 mg.g^-1 fresh weight) were observed in plants grown under red: blue (70:30) and red: blue (30:70) light combinations, respectively. The highest (1.10 mg.g^-1 fresh weight) and lowest (1.01 mg.g^-1 fresh weight) of carotenoid content were found under the red: blue (70:30) and the red: blue (30:70) light combinations, respectively. The maximum essential oil (1.71%) recorded under red: blue (30:70) combination. The highest and the lowest antioxidant activity levels were recorded in the red: blue (50:50) and control light treatments, respectively.
 
Conclusion
The results showed that different light spectra significantly influenced the morphological and physiological characteristics of Hyssopus officinalis. Red light increased morphological and growth characteristics properties. These findings suggested that optimizing light spectra can significantly affected the growth and development of Hyssopus officinalis, and further studies could explore these mechanisms. The results of this study showed that use of modern agricultural methods with artificial lighting systems improved the growth and physiological indices of Hyssop (Hyssopus officinalis). The application of 100% red light and 30:70 red-blue light combinations is recommended.

Keywords

Growth

Leaf area

Light quality

Total chlorophyll

Subjects

• Medicinal Plants

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Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)

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