Effect of CO2 elevation and UV-A radiation on growth responses of Zinnia, Petunia, Coxcomb, and Marigold

In order to evaluate the effect of CO 2 elevation and UV radiation on growth responses of zinnia, petunia, coxcomb, and marigold, a study was conducted in 2015 at Arsanjan Islamic Azad University, Iran. The experimental design was factorial arranged in completely randomized design with three replications. Treatments were included four ornamental species (zinnia, petunia, coxcomb, and marigold), CO 2 concentration at two levels (350 and 700 ppm), and UV radiation at two levels (with and without UV radiation). Results showed that elevating of CO 2 concentration from 350 ppm to 700 ppm increased morphological and physiological characters of C 3 plants, especially marigold. Meanwhile, increasing CO 2 concentration from 350 ppm to 700 ppm, decreased effects of UV damage on plants’ morphological and physiological characters. The highest leaf number, shoot dry mass, plant height and water use efficiency of C 4 plant (coxcomb flower) were observed at 350 ppm of CO 2 concentration without UV radiation while, the highest leaf number, shoot dry mass and leaf pigments of C 3 plants (zinnia, petunia, and marigold flower) were obtained at 700 ppm of CO 2 concentration without UV radiation. The results showed that the activity of catalase and peroxidase enzymes under UV radiation was increased in all of plants. Overall, it is concluded that, the recognition of plants resistant to UV radiation and high levels of CO 2 concentration in the future may be better for environmental production and distribution as ornamental plants in town landscapes, where ecophysiological traits should be considered.