title: Effect of carbohydrates and night temperature on night respiration in rice.
abstract: Global warming causes night temperature (NT) to increase faster than day temperature in the tropics. According to crop growth models, respiration incurs a loss of 40-60% of photosynthate. The thermal sensitivity of night respiration (R(n)) will thus reduce biomass. Instantaneous and acclimated effects of NT on R(n) of leaves and seedlings of two rice cultivars having a variable level of carbohydrates, induced by exposure to different light intensity on the previous day, were investigated. Experiments were conducted in a greenhouse and growth chambers, with R(n) measured on the youngest fully expanded leaves or whole seedlings. Dry weight-based R(n) was 2.6-fold greater for seedlings than for leaves. Leaf R(n) was linearly related to starch (positive intercept) and soluble sugar concentration (zero intercept). Increased NT caused higher R(n) at a given carbohydrate concentration. The change of R(n) at NT increasing from 21 °C to 31 °C was 2.4-fold for the instantaneous response but 1.2- to 1.7-fold after acclimation. The maintenance component of R(n) (R(m)'), estimated by assimilate starvation, averaged 28% in seedlings and 34% in leaves, with no significant thermal effect on this ratio. The acclimated effect of increased NT on R(m)' across experiments was 1.5-fold for a 10 °C increase in NT. No cultivar differences were observed in R(n) or R(m)' responses. The results suggest that the commonly used Q10=2 rule overestimates thermal response of respiration, and R(n) largely depends on assimilate resources.
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Peraudeau
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Tanguy
authors.initials: T
authors.lastname: Lafarge
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Roques
authors.affiliation: International Rice Research Institute (IRRI), Crop and Environment Science Division (CESD), DAPO Box 7777 Metro Manila, Philippines.
authors.forename: Cherryl O
authors.initials: CO
authors.lastname: Quiñones
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Clement-Vidal
authors.affiliation: Bayer CropScience NV, Innovation Center, Technologie park 38, B-9052 Gent, Belgium.
authors.forename: Pieter B F
authors.initials: PB
authors.lastname: Ouwerkerk
authors.affiliation: Bayer CropScience NV, Innovation Center, Technologie park 38, B-9052 Gent, Belgium.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Van Rie
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Fabre
authors.affiliation: International Rice Research Institute (IRRI), Crop and Environment Science Division (CESD), DAPO Box 7777 Metro Manila, Philippines.
authors.forename: Krishna S V
authors.initials: KS
authors.lastname: Jagadish
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France International Rice Research Institute (IRRI), Crop and Environment Science Division (CESD), DAPO Box 7777 Metro Manila, Philippines m.dingkuhn@irri.org.
authors.forename: Michael
authors.initials: M
authors.lastname: Dingkuhn
mesh_terms: D002241:Carbohydrates / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects; D002980:Climate; D003624:Darkness; D005740:Gases / Q000378:metabolism; D008027:Light; D016014:Linear Models; D012275:Oryza / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D012995:Solubility; D013213:Starch / Q000378:metabolism; D013696:Temperature
chemical_list: D002241:Carbohydrates; D005740:Gases; D013213:Starch
keywords: Acclimation; Oryza sativa L.; Q10; maintenance and growth respiration; shading; soluble sugars; starch.