title: Diurnal and developmental changes in energy allocation of absorbed light at PSII in field-grown rice.
abstract: The allocation of absorbed light energy in PSII to electron transport and heat dissipation processes in rice grown under waterlogged conditions was estimated with the lake model of energy transfer. With regard to diurnal changes in energy allocation, the peak of the energy flux to electron transport, J(PSII), occurred in the morning and the peak of the energy flux to heat dissipation associated with non-photochemical quenching of Chl fluorescence, J(NPQ), occurred in the afternoon. With regard to seasonal changes in energy allocation, J(PSII) in the rapidly growing phase was greater than that in the ripening phase, even though the leaves of rice receive less light in the growing phase than in the ripening period in Japan. This seasonal decrease in J(PSII) was accompanied by an increase in J(NPQ). One of the reasons for the lower J(PSII) in the ripening phase might be a more sever afternoon suppression of J(PSII). To estimate energy dissipation due to photoinhibition of PSII, J(NPQ) was divided into J(fast), which is associated with fast-recovering NPQ mainly due to qE, and J(slow), which is mainly due to photoinhibition. The integrated daily energy loss by photoinhibiton was calculated to be about 3-8% of light energy absorption in PSII. Strategies for the utilization of light energy adopted by rice are discussed. For example, very efficient photosynthesis under non-saturating light in the rapidly growing phase is proposed.
authors.affiliation: Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502 Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishida
authors.forename: Nozomu
authors.initials: N
authors.lastname: Uebayashi
authors.forename: Youshi
authors.initials: Y
authors.lastname: Tazoe
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ikeuchi
authors.forename: Koki
authors.initials: K
authors.lastname: Homma
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Endo
mesh_terms: D000042:Absorption; D002940:Circadian Rhythm / Q000528:radiation effects*; D003624:Darkness; D004579:Electron Transport / Q000528:radiation effects; D004734:Energy Metabolism / Q000528:radiation effects*; D008027:Light; D008954:Models, Biological; D012275:Oryza / Q000254:growth & development* / Q000502:physiology* / Q000528:radiation effects; D055668:Photochemical Processes / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D011789:Quantum Theory; D012621:Seasons
chemical_list: D045332:Photosystem II Protein Complex
keywords: Chl fluorescence; Diurnal changes; Energy allocation in PSII; Non-photochemical quenching; Photoinhibition; Rice (Oryza sativa)