ABSTRACT
Aim: The present study was undertaken to study the net photosynthetic rate (Pn), stomatal conductance (gs) and intercellular CO2 (Ci) in five eddoe and four dasheen type taro genotypes under ambient and elevated CO2 , and subjected to different photon flux densities. Methodology: The critical evaluation of Pn was assessed at different photosynthetic photon flux densities (PPFDs) viz., 200, 400, 600, 800, 1000, 1200 and 1500 µmol m-2 hr-1 under ambient CO2 (400 ppm) and at saturation PPFD (1500 µmol m-2 hr-1) at short-term (ten min) exposure of leaves to elevated CO2 (eCO2; 600, 800 and 1000 ppm) at 30oC using portable photosynthesis system LI-6400, LICOR, USA in a controlled-climate cuvette system. Results: The Pn in the leaves of nine taro genotypes persistently augmented upon short-term (10 min) exposure to eCO2 concentrations which ranged between 400 ppm and 1000 ppm. Taro genotypes exhibited 61.80 – 113.3% hike in Pn at eCO2 (1000 ppm) as compared to ambient CO2 (400 ppm). However, the per cent increase in Pn at eCO2 for every 200 ppm between 400 to1000 ppm significantly declined (4.4-18.4%) at 1000 ppm CO2. The differences in gs were statistically significant across taro genotypes (P>0.001) and CO2 concentrations (P>0.001). Further, the Ci was also found to increase constantly at eCO2 concentrations (400 ppm to 1000 ppm). However, there was significant reduction (16.2 - 31.3%) in Ci for every 200 ppm between 400-1000 ppm. Interpretation: Results of the study revealed that the genotypes Muktakeshi, Sree Pallavi and Telia are promising in the context of climate change as they significantly responded to eCO2 concentrations. Response mechanism to eCO2 need to be elucidated.