title: Environmental modification of yield and nutrient composition of 'Waldmann's Green' leaf lettuce.
abstract: Leaf number, dry weight, and nutrient composition of Lactuca sativa L. cv. Waldmann's Green leaves were compared following 9 days of treatment in a controlled environment room under various combinations of photosynthetic photon flux (PPF:350 vs 800 micromoles m-2 s-1), atmospheric CO2 level (ambient vs 1500 micromoles mol-1), and single-strength (1X:15 mM) vs double-strength (2X:30 mM) nitrogen (N) as NO3- alone or as NH4(+) + NO3- (1:5 molar ratio). CO2 enrichment greatly enhanced leaf number under all PPF and N conditions, but increased leaf dry weight only at high PPF. Conditions favoring high photosynthesis enhanced leaf starch content 3-fold, and protein content increased as much as 64% with 2X NH4(+)+NO3-. Free sugar content was 6 to 9% of leaf dry weight for all treatment combinations, while fat was 1.5 to 3.5%. Ash content varied from 15 to 20% of leaf dry weight. Modified controlled environments can be used to enhance the nutritional content as well as the yield of crops to be used for life support in space-deployed, self-sustaining human habitats. Leaf lettuce is a useful model crop for demonstrating the potential of nutritional value added by environmental manipulation.
authors.affiliation: Department of Horticulture, NASA Specialized Center of Research and Training in Bioregenerative Life Support, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Mitchell
authors.forename: C
authors.initials: C
authors.lastname: Chun
authors.forename: W E
authors.initials: WE
authors.lastname: Brandt
authors.forename: S S
authors.initials: SS
authors.lastname: Nielsen
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004780:Environment, Controlled; D018545:Lactuca / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D009566:Nitrates / Q000494:pharmacology; D009584:Nitrogen / Q000494:pharmacology*; D009753:Nutritive Value; D017785:Photons; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology
chemical_list: D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D002245:Carbon Dioxide; D009584:Nitrogen