INFLUENCE OF ELEVATED CO2 ON THE GROWTH AND PHENOLIC CONSTITUENTS PRODUCTION IN HIBISCUS SABDARIFFA VAR. UKMR-2

The impact of global climate change on plants which has been widely reported can exhibit significant changes on the growth, yield and metabolite production. Studies on the impact of elevated carbon dioxide concentration, [CO 2 ] on plant growth and production of phenolic constituents in Hibiscus sabdariffa var. UKMR-2 has not been reported in any previous studies. This study investigated the growth quality and production of phenolic constituents of UKMR-2 under different [CO 2 ]. The cultivation was subjected to two atmospheric [CO 2 ]; ambient (400 µmol/mol), and elevated (800 µmol/mol). Selected parameters for growth performance were recorded throughout the plant development. UKMR-2 calyx extract was analysed for total phenolic, total anthocyanins, antioxidant activity, and evaluated based on HPLC-PDA method. The results revealed that UKMR-2 responded differently to the [CO 2 ] treatments. The results clearly showed that exposure to elevated [CO 2 ] increased calyx yields, production of phenolic constituents, and antioxidant activity. Furthermore, different [CO 2 ] had significant interaction on the production of phenolic constituents, and antioxidant activity (p < 0.05), except for plant growth. The HPLC-PDA showed the presence of delphinidin-3- O -sambubioside, cyanidin-3- O -sambubioside, ascorbic acid, caffeic acid, and chlorogenic acid. Therefore, increased [CO 2 ] may have significant effects on UKMR-2 to not only produce higher production yields, but also on the production of phenolic constituents with potential physiological impact to human health.