Photosynthetic Responses of Mangrove Plant (Rhizophora apiculata) to Elevated Atmospheric CO2 Concentration

In order to choose tree species that are climate change-adaptive, this study looked into the photosynthetic characteristics of the mangrove plant R. apiculata in response to increased atmospheric CO2 concentration. The seedlings were cultivated for nearly three months in environment-controlled growth chambers with two CO2 concentration combinations: (i) 28oC + CO2 420±20 ppm (control) and (ii) 28oC + CO2 650±20 ppm (elevated). Reduced tree height and physiological characteristics, such as protein and nitrogen levels and chlorophyll, were seen in the seedlings under the increased treatment. Specifically, a significant decrease in chlorophyll that is directly linked to the carbon dioxide fixative reaction system was the outcome of the increased treatment. Under the increased treatment, varying degrees of loss in photosynthetic characteristics were observed. Furthermore, at higher CO2, there was a noticeable decrease in the characteristics of the CO2 fixative reaction system, including the triose phosphate utilization (TPU) limitation (33%) lower rate, the ribulose-1,5-bisphosphate (RuBP) regeneration rate (35%), and the Rubisco activity rate (33%). These findings imply that the reduced CO2 fixative reaction system, rather than the photochemical reaction system, may be responsible for the low level of photosynthetic capability. Keywords: Mangrove, Photosynthetic rates, Rubisco, Elevated CO 2