Effect of elevated CO2 and temperature on oxidative stress and antioxidant enzymes activity in coconut (Cocosnucifera L.) seedlings
Increasing atmospheric CO2 concentration is one of the factors driving climate change. We have investigated the individual effect of elevated CO2 and temperature on oxidative stress and antioxidant enzymes activity in coconut (Cocosnucifera L.) seedlings. Three cultivars (WCT, LCT and COD) and two hybrids (WCT × COD and COD × WCT) were grown in six open top chambers (OTCs) and responses were analyzed after three years. In two OTCs the CO2 was set at 550 and 700 µmol mol−1 and control chamber had ambient level of 393 µmol mol1. In two separate OTCs, air temperature was elevated by 2 °C above the ambient control chamber. Remaining two chambers served as chamber control. Elevated CO2 and temperature increased the activities of superoxide dismutase and catalase , whereas it reduced polyphenol oxidase activity. On the other hand, peroxidase (POX) activity was decreased in elevated temperature, while it increased under elevated CO2 conditions. The POX activity and membrane stability index (MSI) were positively correlated. By virtue of greater MSI and lower MDA content, WCT and hybrid COD × WCT were observed to be tolerant to oxidative stress among the five cultivars under elevated CO2 and temperature conditions. These cultivars may adapt better to changing climates.