The Morphological characteristics of Pterocarpus indicus induced by Elevated Ozone under Well-watered and Drought conditions

Abstract

The present study was conducted to examine the response of Pterocarpus indicus to elevated ozone by comparing the effects between well-watered and soil drought treatments. The ozone concentration was 200 ppb and the exposure was conducted for a month with well-watered and soil drought treatments in chamber environmental conditions. Elevated ozone-induced visible injuries to P. indicus varied among the well-watered environmental conditions, with the appearance of light green chlorosis in the SWO seedlings over time. However, in the SDO seedlings, no difference was visible between drought and drought with ozone treatment. Shriveled leaves were evident because of the water deficiency. Moreover, elevated ozone induced leaf stomata injury and a harsh abaxial surface, whereas drought stress induced less injured stomata because of stomata closing. In addition, the palisade tissues exhibited smaller chloroplasts, damaged thylakoid, increased plastoglobuli, decreased starch grain and thinner cell walls on the upper leaf surface. Thus, the SDO seedlings were less influenced by elevated ozone stress than SWO seedlings due to the reduced ozone absorption which caused by stomata closing to prevent water loss.