Effect of UV-B radiation on anatomical structure of Pelargonium graveolens L. Her

Pelargonium graveolens L′Her is an aromatic and medicinal plant that is widely used in pharmaceutical, perfumery and food industry. Ultraviolet radiation has many effects on plants and can cause many morphological and physiological changes that often decreased plant growth. In this study to investigate the effect of ultraviolet radiation on the anatomical structure of different organs of P.graveolens, the plant cuttings were exposed to different intensities of ultraviolet radiation -B (0, 0.12, 0.26 , 0.38 W/m2). The structure of leaves, stem, petiole and root of the plants were studied by light microscope. The results indicated that with increasing UV radiation, leaf thickness decreased and the size petiole thickness increased. Maximum level of the central vascular bundle diameter of petiole and stem were seen in high UV-B intensity treatment. Also results showed in petiole and stem of treated plants, parenchyma thickness decreased and the area of the stele increased by enhancing UV radiation intensity. However, in all treatments, the root structure was not affected. Considering alteration in results, it seems that shoots anatomy were affected by UV-B radiation especially in higher dose, but this radiation had no effect on root structure.