Physiological and Morphological Responses to Ozone Exposure of Coleus (Solenostemon scutellarioides (L.) Codd)

Abstract

The tropospheric ozone has been projected to increase and it could harm humans, animals, and vegetation. The objectives of this study were to investigate morphological changes in coleus leaves, to assess the change of pigment composition (chlorophyll, carotenoid, and anthocyanin), and to understand color dynamics due to ozone fumigation. Coleus Kong Green (fully green/FG), Coleus Kong Scarlet (green and purple/GP), Coleus Wizard Pastel (yellow and purple/YP), and Coleus Wizard Scarlet (reddish/RD) had been selected and tested into three different ozone concentrations which were CF (≤ 10 ppb ozone), CF+40 ppb ozone, and CF+150 ppb ozone for 8 hours/day for 30 days. Chlorosis in FG and curling leaf in RD were observed as the symptoms while other cultivars showed different appearances such as expanded purple area (GP and YP) and curl margin (RD). Chlorophyll and carotenoid content significantly decreased in all cultivars while anthocyanin was found increasing except in RD. The color change tended to redder and brighter in all cultivars except RD which was stable and purple area in GP which was darker. Therefore, different coleus cultivars show different responses and it can be used as ozone-plant model to investigate pigment composition under ozone exposure.