Assessment of Visible Injury Impact due to Tropospheric Ozone(O₃) on Shola Forest Seedlings, Grassland Species and Tea Ecosystem with Silver Oak Tree System at Western Ghats of Nilgiris by a Tool of Ozone Injury Index (OII)

A powerful oxidant, tropospheric ozone (O₃) has the potential to harm natural, agricultural, and horticultural plant species. Research into the effects of ozone has been extensive, but despite this effort, there is still a great deal of uncertainty regarding the levels of ozone that are harmful to plant species. Much of the scientific research effort focused on the impact of tropospheric ozone(O₃) on shola forest seedlings, grasses, tea and silver oak plant species at high altitude region of Nilgiris (2520 m a.m.s.l) and it was assessed by continuous examination at different elevated levels(50, 100 &200ppb) of tropospheric ozone (O₃) on these plant species and it was compared with control plant species of the specified ecosystem in Open Top Chamber (OTC) through identified symptoms and its severity of injury by visual scoring method of Ozone Injury Index (OII). Based on the OII in percentage, the shola species namely Ligustrum perrottetii(8.33, 9.09, &10.86) and grass sepecies viz., Poa annua (25, 36.36&38.46), Pennisetum clandestinum(20, 20&16.66), Ergrostis unioloides (30, 37.5&40), Ergrostis spp (25, 13.33, &30.43) and Vetiveria zizanioides(16.66, 16.66 &16.16) showed moderately tolerant OII at 50, 100 & 200ppb levels of tropospheric ozone (O₃) compared to control plants and the other species were showed the OII of moderately severe, severe and very sever. The study concluded that the species in high altitude region of the specified ecosystem act as bioindicators for tropospheric ozone(O₃₎ at elevated levels and there is a need for a more detailed study with the focus on plant physiological and biochemical parameters of these species of a specified ecosystem.