چكيده انگليسي :
The plant Zinnia elegans, commonly known as Zinnia, is an important and widely used plant in the floriculture industry. Zinnia is one of the plants that is tolerant to drought and high light intensity, and it can continue to grow and bloom even under stressful and harsh conditions. The presence of supplementary LED lights as an energy source alongside sunlight is one of the factors that, after selecting the appropriate genotype, is crucial for increasing the productivity and efficiency of plant production. This study was conducted in two experiments in a completely randomized factorial design containing by two factors: genotype and LED light. In the first study, the genotype treatment included three colors: orange, pink, and yellow flower, and the light treatment included five spectra: red, blue, white, red-blue, and natural sunlight as the control light. These treatments were applied to mature Zinnia plants in such a way that the plants were exposed to 12 hours of LED light and 12 hours of natural light for 30 days after seed planting and transfer to the greenhouse, and then treated with LED lights continuously for 15 days. The effects of these two treatments on the morphological traits of Zinnia showed that the red-blue light spectrum significantly affected many traits such as days to flowering, leaf indices, central disc diameter, and inflorescence diameter. The red light spectrum increased the height and number of lateral branches in mature plants. Traits such as the pattern of radial floret rotation and stem diameter did not show significant differences with the control under light treatments. Concerning genotype evaluation, it was observed that the orange genotype increased traits such as height, leaf indices, inflorescence diameter, disc diameter, and number of inflorescences. The second study was conducted on Zinnia seedlings with two genotype treatments in four colors: pink, fiery red, white, and yellow, and light treatments in five spectra similar to the first study. In this research, morphological and physiological traits were measured in the seedlings. Based on these results, the red light spectrum increased traits such as the number of leaves, stem diameter, leaf indices, root density, fresh and dry weight of aerial parts, and fresh and dry weight of the stem. In the physiological traits section, the red light spectrum increased the concentration of carotenoid pigments, chlorophyll a, b, and total chlorophyll. The red-blue light spectrum increased morphological traits such as fresh leaf weight, dry root weight, fresh root weight, and root volume. The blue light spectrum was effective in increasing root length and could also increase plant height compared to the control. On the other hand, the red-blue light spectrum reduced the concentration of catalase and peroxidase in the plant, which may indicate reduced environmental stress on the plant under LED light conditions.
