title: Diurnal Solar Energy Conversion and Photoprotection in Rice Canopies.
abstract: Genetic improvement of photosynthetic performance of cereal crops and increasing the efficiency with which solar radiation is converted into biomass has recently become a major focus for crop physiologists and breeders. The pulse amplitude modulated chlorophyll fluorescence technique (PAM) allows quantitative leaf level monitoring of the utilization of energy for photochemical light conversion and photoprotection in natural environments, potentially over the entire crop lifecycle. Here, the diurnal relationship between electron transport rate (ETR) and irradiance was measured in five cultivars of rice (Oryza sativa) in canopy conditions with PAM fluorescence under natural solar radiation. This relationship differed substantially from that observed for conventional short term light response curves measured under controlled actinic light with the same leaves. This difference was characterized by a reduced curvature factor when curve fitting was used to model this diurnal response. The engagement of photoprotective processes in chloroplast electron transport in leaves under canopy solar radiation was shown to be a major contributor to this difference. Genotypic variation in the irradiance at which energy flux into photoprotective dissipation became greater than ETR was observed. Cultivars capable of higher ETR at midrange light intensities were shown to produce greater leaf area over time, estimated by noninvasive imaging.
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., S.v.C., R.F.).|High Resolution Plant Phenomics Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., R.F.).|International Rice Research Institute, Los Baños, 4031 Laguna, Philippines (W.P.Q.); and.|University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom (W.P.Q.).
authors.forename: Katherine
authors.identifier: 0000-0003-1198-5389
authors.initials: K
authors.lastname: Meacham
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., S.v.C., R.F.).|High Resolution Plant Phenomics Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., R.F.).|International Rice Research Institute, Los Baños, 4031 Laguna, Philippines (W.P.Q.); and.|University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom (W.P.Q.).
authors.forename: Xavier
authors.identifier: 0000-0002-4873-1844
authors.initials: X
authors.lastname: Sirault
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., S.v.C., R.F.).|High Resolution Plant Phenomics Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., R.F.).|International Rice Research Institute, Los Baños, 4031 Laguna, Philippines (W.P.Q.); and.|University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom (W.P.Q.).
authors.forename: W Paul
authors.initials: WP
authors.lastname: Quick
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., S.v.C., R.F.).|High Resolution Plant Phenomics Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., R.F.).|International Rice Research Institute, Los Baños, 4031 Laguna, Philippines (W.P.Q.); and.|University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom (W.P.Q.).
authors.forename: Susanne
authors.initials: S
authors.lastname: von Caemmerer
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., S.v.C., R.F.); robert.furbank@anu.edu.au.|High Resolution Plant Phenomics Centre, Commonwealth Scientific and Industrial Research Organization (CSIRO), CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia (K.M., X.S., R.F.); robert.furbank@anu.edu.au.|International Rice Research Institute, Los Baños, 4031 Laguna, Philippines (W.P.Q.); and robert.furbank@anu.edu.au.|University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom (W.P.Q.) robert.furbank@anu.edu.au.
authors.forename: Robert
authors.initials: R
authors.lastname: Furbank
mesh_terms: D018533:Biomass; D002940:Circadian Rhythm; D004579:Electron Transport / Q000502:physiology; D005453:Fluorescence; D012275:Oryza / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology*; D012993:Solar Energy; D013472:Sunlight