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Authors
Info
V. Ravi1*,
S.J. More1, R. Saravanan2,
G. Byju1,
M. Nedunchezhiyan4,
A.A. Devi3
and K.P. Nair1Â
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1Division of Crop
Production,
ICAR –Central Tuber Crops Research
Institute, Thiruvananthapuram-695 017, India
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2Division of Crop
Utilization,
ICAR – Central Tuber Crops Research
Institute, Thiruvananthapuram-695 017, India
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3Division of Crop
Improvement, ICAR–Central Tuber Crops Research Institute,
Thiruvananthapuram–695 017, India
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4ICAR- Regional
Centre of Central Tuber Crops Research Institute, Bhubaneswar-751 019, IndiaÂ
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*Corresponding Author Email :
veluravi03@yahoo.co.in
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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. Â
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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. Â Â Â Â Â
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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.Â
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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.
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Key
words:
Colocasia esculenta, Climate change, Elevated CO2, Net
photosynthesis, Stomatal conductance
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