Exogenous ascorbic acid scarcely ameliorates inhibition of photosynthesis in rice leaves by O₃
2017
Kobayakawa, Hiroki | Imai, Katsu
The role of ascorbic acid on acute O₃-induced inhibition of photosynthesis in solution-cultured paddy rice was evaluated. As pre-treatment, ascorbic acid (0, 5, and 10 mM) was added to the culture solution for 5 d before 5 h of O₃ exposure (0, .1, and .3 cm³ m⁻³ O₃) during daytime. O₃ decreased photosynthesis-related parameters, total ascorbic acid content, and the redox state (RDS) of ascorbic acid. Ascorbic acid treatment enhanced the total ascorbic acid contents and its RDS level of rice leaves, but scarcely ameliorated O₃-induced inhibition of photosynthesis-related parameters. Inhibition of net photosynthetic rate (PN) by O₃ was slightly ameliorated by exogenous ascorbic acid only at 1 d after O₃ exposure. These results indicate that ascorbic acid is a component of protection from O₃ injury but has a marginal role in the acute inhibition of PN by O₃ in rice leaves.
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