Diurnal flux in CO2 associated with Pongamia pinnata (L.) Pierre grown under controlled microclimatic conditions

Abstract

The present study is an attempt to assess the growth and biochemical responses of Pongamia pinnata grownunder elevated levels of CO2 supply. Saplings (18 months) maintained in the nursery were brought toexperimentation in two growth chambers having controlled supply of air and air- CO2 mixture, for a periodof 15 days. The control and treated chambers were retained at an average CO2 concentration of 505.28±17.39 ppm and 1053.85± 24.99 ppm respectively. Day and night fluxes of CO2 within the chambers wereanalysed daily, along with a periodic assessment of the growth and biochemical responses associated withthe plants. A standardization study, excluding plants, was also attempted to assess the resultantflux ofCO2 associated with the growth chambers. The day flux of CO2 in the control and treatedchambers wasdifferent from that of the night flux in both experimentation and standardization studies. Higher CO2assimilation by the plants in the CO2 enriched system during the day time has also resulted in increasedplant height, stem thickness, leaf area and also in the assimilation of carbohydrates, sodium and potassium.Increased Carotenoids and phenol are implications of the stress to which the plants are subjected to underelevated levels of CO2 supply. The present study confirms that, despite certain signs of stress, Pongamiapinnata can be an ideal candidate for carbon offset planting.