title: Growing wheat in Biosphere 2 under elevated CO2: observations and modeling.
abstract: Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.
authors.affiliation: Columbia University, NASA-Goddard Institute for Space Studies, New York 10025, USA.
authors.forename: F N
authors.initials: FN
authors.lastname: Tubiello
authors.forename: T
authors.initials: T
authors.lastname: Mahato
authors.forename: T
authors.initials: T
authors.lastname: Morton
authors.forename: J W
authors.initials: JW
authors.lastname: Druitt
authors.forename: T
authors.initials: T
authors.lastname: Volk
authors.forename: B D
authors.initials: BD
authors.lastname: Marino
mesh_terms: D000383:Agriculture; D018533:Biomass; D002245:Carbon Dioxide / Q000494:pharmacology*; D003198:Computer Simulation; D018504:Ecological Systems, Closed; D004780:Environment, Controlled; D008021:Life Support Systems; D008027:Light; D008954:Models, Biological; D011237:Predictive Value of Tests; D013696:Temperature; D014908:Triticum / Q000187:drug effects / Q000254:growth & development*
chemical_list: D002245:Carbon Dioxide