Document Type : Research Article
Authors
1 Postdoc researcher of Department of Horticultural Sciences and Landscape Designing, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
2 Professor of Department of Horticultural Sciences and Landscape Designing, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
3 Associate professor of Department of Horticultural Sciences and Landscape Designing, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
Abstract
1. Title: The improvement of germination, growth, and biochemical indices of Echium amoenum Fisch & Mey. under different light qualities
2. Introduction: Medicinal plants, as a valuable source of herbal medicines and bioactive compounds, are rapidly declining due to uncontrolled collection from nature. Echium amoenum Fisch & Mey. belongs to the Boraginaceae family and has a special place in Iranian traditional medicine. This plant is native to Iran and has been used to treat many infectious and inflammatory diseases, as well as modern diseases related to stress and anxiety, for many years. However, low germination percentage and uneven germination are some of the obstacles to the growth and propagation of this valuable medicinal plant. Recently, it has been reported that LED light sources have significantly increased the germination of some medicinal species. The response of plants to light spectra depends on the plant species. However, blue and red light are more useful because green plant tissues more readily absorb them. Considering the medicinal importance of E. amoenum, the present study was conducted to improve the germination and growth characteristics under LED treatments.
3. Materials and methods: This study was conducted at the University of Mohaghegh Ardabili in 2024. E. amoenum seeds were purchased from Pakan Bazr Company. After surface disinfection, the seeds were placed in Petri dishes containing wet filter paper and transferred to light chambers. Germination indices (germination percentage, speed of germination, mean daily germination, germination energy, seed efficiency, seedling efficiency, seedling vigor index, coefficient of velocity of germination, daily germination speed) were recorded for up to 21 days. Morphological indices (fresh weight of seedling, dry weight of seedling, shoot length, root length, percentage of root dry weight, percentage of shoot dry weight) were measured in 7-day-old seedlings. Then seedlings were transferred to the growing medium (peat moss and perlite), and the pots were placed in the same light chambers. After 4 weeks, biochemical indices (photosynthetic pigment content, total carbohydrate content, total protein content, and total phenol content) were evaluated. The experiment was conducted based on a completely randomized design with 4 treatments and 4 replications. The 4 light treatments included 100% white LED light (W), 100% blue LED light (B), 100% red LED light (R), and a combination of blue and red LED light (50:50, BR). The data were analyzed using SPSS Inc. version 16. Means were compared using Duncan's multiple range test at a 5% probability level. Graphs were drawn using Excel software.
4. Results and Discussion: The results of the present study revealed that red light (R) treatment significantly improved germination percentage, germination speed, mean daily germination, germination energy, seed efficiency, seedling efficiency, seedling vigor index, coefficient of velocity of germination, and blue light (B) application reduced the germination of E. amoenum seeds. Similarly, E. amoenum growth characteristics, including fresh weight, dry weight, seedling length, root length, percentage of root dry weight, and percentage of shoot dry weight, increased under the positive effect of red LED light (R). Also, the blue light (B) application did not indicate any positive effect on growth indices. In biochemical indices, the application of a combination of blue and red light (BR) resulted in a significant increase in the content of photosynthetic pigments, total carbohydrate content, total protein content, and total phenol content. In addition, blue LED light (B) had a negative effect on biochemical indices compared to other treatments. In general, light quality changes can affect photosynthesis and energy production efficiency. Blue and red light are known to be the most effective wavelengths for plants, and their absorption peaks correspond to the absorption peaks of photosynthetic pigments. Therefore, their application alone and in combination can effectively increase the efficiency of photosynthesis, the synthesis of photosynthetic pigments, and the biosynthesis of macromolecules including carbohydrates and proteins. In addition, applying blue and red light increases phenolic compounds by increasing the production of enzymes related to plant secondary metabolism.
5. Conclusion: The observations of the present study showed that the seeds of E. amoenum are considered in the group of plant species that require light or are photoblastic positive. Hence, the application of red LED (R) can be considered an effective treatment to improve and increase the germination and growth characteristics of E. amoenum plant at the seedling stage. In the later stages of plant growth, the response of E. amoenum to light qualities was different. The combination of blue and red light (BR) was considered an effective treatment to increase the content of photosynthetic pigments, total carbohydrates, total proteins, and total phenols.
6. Acknowledgement: We would like to thank the University of Mohaghegh Ardabili for financial support.
7. Keywords: Chlorophyll, Germination percentage, Morphological, Phenol, Protein
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