Title: Genotypic variation of photosystem II photoinhibition and energy partitioning in relation to photosynthetic adaptability to mild soil water deficiency of rice cultivation in northeast Thailand
Abstract: Mild intermittent drought is one of the major factors of yield reduction in rainfed rice. To minimize the yield reduction, the mechanisms that maintain photosynthetic activity play a crucial role for sufficient plant growth. The photoinhibition of photosystem II (PSII) depends on the balance between the rate of energy absorption and the rate of energy dissipation, including the energy flux for photosynthesis. Photoinhibition decreases the photosynthetic rate and restricts the primary production of the plant. In contrast, PSII photoinhibition can be regarded as a redox control mechanism that alleviates the excess light energy. In this study, the genotypic variation of photoinhibition in rice was examined in relation to the adaptability of photosynthesis to the fluctuating soil water conditions. 20 rice genotypes were grown under flooded and aerobic conditions, and the midday photoinhibition was evaluated by measuring the maximum quantum yield of PSII (Fv/Fm, a parameter of chlorophyll fluorescence). The larger decrease in Fv/Fm under aerobic condition than flooded condition was thought to be caused by the photosynthetic depletion derived from stomatal closure. The decrease of Fv/Fm occurred concomitantly with the increase of non-photochemical quenching (NPQ). Enhanced photoinhibition and NPQ might oxidize the redox state of the plastoquinone (PQ) pool under the aerobic condition to the same level as that under the flooded condition. The genotypic variation of the Fv/Fm and energy partitioning were affected little by the mild soil water deficiency of the aerobic condition. The genotypic variation of the midday Fv/Fm was dependent on the decreasing rate of Fv/Fm against an increase in midday light intensity. Some genotypes that showed more severe midday photoinhibition tended to have a lower rate of reduction of the shoot dry weight under the aerobic condition. These findings suggest that photoinhibition is a preferable trait for energy control in PSII and for photosynthesis under mild soil water deficiency.
Publication Year: 2013
Publication Date: 2013-02-28
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 3
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