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Aim: The present study was undertaken to study the net photosynthetic rate (P-n), stomatal conductance (g(s)) and intercellular CO2 (C-1) 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 P, was assessed at different photosynthetic photon flux densities (PPFDs) viz., 200. 400, 600, 800, 1000, 1200 and 1500 mu mol m(-2) hr(-1) under ambient CO2 (400 ppm) and at saturation PPFD (1500 pmol m(2) hr(-1)) at short-term (ten min) exposure of leaves to elevated CO2 (eCO(2); 600, 800 and 1000 ppm) at 30 degrees C using portable photosynthesis system LI-6400, LICOR, USAin a controlled-climate cuvette system.

Results: The P-n in the leaves of nine taro genotypes persistently augmented upon short-term (10 min) exposure to eCO(2) concentrations which ranged between 400 ppm and 1000 ppm. Taro genotypes exhibited 61.80 +/- 113.3% hike in P-0 at eCO(2) (1000 ppm) as compared to ambient CO2 (400 ppm). However, the per cent increase in P at eCO(2) for every 200 ppm between 400 to1000 ppm significantly declined (4.4-18.4%) at 1000 ppm CO2. The differences in g were statistically significant across taro genotypes (P>0.001) and CO2 concentrations (P>0.001). Further, the C. was also found to increase constantly at eCO(2) concentrations (400 ppm to 1000 ppm). However, there was significant reduction (16.2 - 31.3%) in Cifor 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 eCO(2) concentrations. Response mechanism to eCO(2) need to be elucidated.