Structural and functional alteration of photosynthetic apparatus in rice under submergence
Debabrata Panda | R. K. Sarkar
Submergence induced alteration of photo-system II (PS II) structure and function was probed using fast O-J-I-P chlorophyll a fluorescence transient and CO2 photo-assimilation rate. Submergence resulted in an inhibition of CO2 photo-assimilation rate and reduction in leaf chlorophyll content in rice but the decrease was more in submergence susceptible (IR 42) and avoiding type (Sabita) cultivars compared to the tolerant (FR 13A) one. Quantification of the chlorophyll a fluorescence transients (JIP-test) revealed large cultivar differences in the response of PS II to submergence. The kinetics of chlorophyll a fluorescence transient showed complex changes in the magnitude and rise of O-J, J-I and I-P phases of fluorescence rise. Due to submergence both donor and acceptor sides of PS II were damaged and electron transport perturbed, which resulted in the fall of CO2 photo-assimilation rate. Submergence also affected overall grouping probability (PG) or energetic connectivity between PS II antennae. The fall of PG was greater in submergence susceptible and avoiding types of cultivar compared to the tolerant one. These indicate that chlorophyll fluorescence can be used to know the sensitivity of rice to submergence stress.
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