Tropospheric ozone is a phytotoxic gaseous pollutant with global warming potential that disrupts the plants growth and development directly or through climate change. Ozone enters into a plants body through stomatal pores and develops oxidative stress, which results in injury to foliage and modifies leaf micro-morphology and anatomy. A field study was conducted to assess the morphological, micro-morphological, and anatomical response of groundnut cultivars (Arachis hypogaea L.) to enhance the level of ozone. This study observed ozone-like visible injury symptoms on all groundnut cultivars. Visible injury was maximum in cultivar Dh-86 and minimum in cultivar TPG-41. Micro-morphological characteristics, such as increase in stomata, epidermal cells number, and its index, were also increased under enhanced ozone-exposed plants. The highest stomatal index was found in cultivar TPG-41 and lowest were noted in cultivar GG-20. Cultivars TAG-24 > TG-37A > and Dh-86 show moderate modification in the morphological and micro-morphological characteristics of plants. Elevated ozone also affected the stomatal movement and leaf internal tissue. Most of the stomata of all the groundnut cultivars were observed as closed during the enhanced ozone exposure, suggesting a protective mechanism from ozone stress. The study concluded that the micro-morphological and anatomical characteristics are important aspects to determine the effect of ozone on plants and to influence plants sensitivity to ozone. On the basis of these characteristics, cultivar TPG-41 was found to be less sensitivity, while cultivar Dh-86 was found to be highly sensitive to ozone pollution.
Key words: Arachis hypogaea, Tropospheric Ozone, OTC, Visible Injury, Micromorphology, Anatomy, Ozone resistant and sensitive variety