Characterizing the photosynthetic ability of the submergence-tolerant rice variety of Inpari30 via maximum quantum yield performance during transient flooding stress and recovery

Abstract

Submergence is an environmental challenge for crop cultivation which causes physiological perturbation and yield loss. Tolerant genotypes are characterized by the ability to maintain physiological processes, especially photosynthesis, minimizing the negative effects of flooding stress. This experiment was aimed to examine the photosynthetic ability during submergence and a recovery period in rice variety of Inpari30 (carrying gene Sub1) compared to IR72442 (an elongation type) under control and submergence treatment. A randomized complete block design was employed in this experiment with three replications. The first factor was the environmental condition consisting of control and submergence. The second factor was rice varieties consisting of Inpari30 and IR72442. Fourteen-day-old seedlings were submerged under 35 cm of water depth for 6 days and re-aerated by lowering the water level up to the stem base for 6 days of recovery. Measurement of plant height, SPAD, Fv/Fm and photosynthetic rate were taken continuously from the same plant sample following the experimental stage. The results showed that shoot length increased significantly more in IR72442 than in the quiescent Inpari30. The noticeable decline was observed in the photosynthetic rate of both varieties during submergence with chlorophyll content and chlorophyll fluorescence (Fv/Fm) decreased more severely in IR72442 than in Inpari30. After flooding, Inpari30 adapted quickly to the aerobic environment, as shown by a recovery in Fv/Fm and accumulated dry weight more quickly than IR72442. We concluded that the Sub1 genotype of Inpari30 confers the ability to maintain maximum quantum yield of PSII under conditions of limiting gas exchange for photosynthesis for adapting post submergence