Potential increase in photosynthetic response of taro (colocasia esculenta l.) to photon flux density and elevated c02

Abstract

Aim: The present study was undertaken tostudy the net photosynthetic rate (Pp), stomatal conductance (gj and intercellular C02 (C,) in five eddoe and four dasheeri type taro genotypes under ambient and elevated C02,and subjected to different photon fluxdensities. Methodology: The critical evaluation of P, was assessed at different photosynthetic photon flux densities (PPFDs) viz., 200, 400, 600. 800, 1000, 1200 and 1500 pmol m"2 hr"1 under ambient C02 (400 ppm) and at saturation PPFD (1500 pmol m'2 hr'1) at short-term (ten min) exposure of leaves to elevated C02 (eC02; 600. 800 and 1000 ppm) at 30°C using portable photosynthesis system LI-6400, LICOR. USAin a controlled -climate cuvette system. Results: The P. in the leaves of nine taro genotypes persistently augmented upon short-term (10 min) exposure to eC02 concentrations which ranged between 400 ppm and 1000 ppm. Taro genotypes exhibited 61.80 - 113.3% hike in Pp at eC02(1000 ppm) as compared to ambient C02 (400 ppm). However, the per cent increase in Pp at eC02 for every 200 ppm between 400 to1000 ppm significantly declined (4.4-18.4%) at 1000 ppm C02. The differences in g5 were statistically significant across taro genotypes (P>0.001) and C02 concentrations (P>0.001). Further, the Qwas also found to increase constantly at eC02 concentrations (400 ppm to 1000 ppm). However, there was significant reduction (16.2 - 31.3%) in C.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 toeC02 concentrations. Response mechanism to eC02 need to be elucidated.