Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges &
Opportunities during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
temperature in pearl millet. Our results indicate that Oxygen Evolution Complex (OEC)
damage is the primary effect of heat stress and is not seen in the elevated CO 2 conditions. Low
exciton absorption flux in heat stress caused an electron transport traffic jam in the donor side
of PSII. Our results indicate that the functional state of photosystem II has differentially
sensitivity to heat and elevated CO 2. Maximum quantum yield of Photosystem II
photochemistry reduced in G2 and G3 gradient chambers in both elevated temperature and
elevated CO 2. C 4 plants have a higher temperature optimum for photosynthesis. The driving
force for higher dry matter production under eCO 2 in combination with temperature is more
due to an optimum temperature rather than elevated CO2. Elevated CO2 mitigated the adverse
effect of G1(Ambient + 1.5 ± 0.5℃) on photosystem II electron transport.
We bring out the mechanism by which maximum quantum yield of Photosystem II
photochemistry reduced in G2 and G3 gradient chambers in both elevated temperature and
elevated CO 2. It was shown that OEC was affected in the plants reflecting in low
photosynthetic efficacy in the higher gradients of temperature and was not affected by elevated
CO 2. The possible reason for this was seen as C4 plants have a higher temperature optimum
for photosynthesis. A model (Fig.) was developed to show how photosystem II was affected
by eCO2 and high temperature.
Electron transport model of PSII under eCO2 and G1 and G2 gradients of high temperature
387 | Page Managing genetic resources for enhanced stress tolerance