Influences of Nitrogen Supply and Elevated CO2 on Nitrogen Consumption, Nitrogen Loss, Tissue Nitrogen Concentration, and Yield of Hydroponic Wheat

Author

Karl B. Ritchie, Utah State University

Date of Award:

5-1994

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plants, Soils, and Biometeorology

Committee Chair(s)

Bruce Bugbee

Committee

Bruce Bugbee

Committee

Jennifer MacAdam

Committee

Jenny Norton

Committee

John Stark

Abstract

Wheat was grown hydroponically for 23 days (early boot stage) in a controlled environment at NO₃^- concentrations of 100 and 1000 μmol and CO₂ levels of 360 and 1200 μmol mo1^-1. Nitrogen consumption and transpiration were measured daily. Tissue nitrogen concentration, total biomass, and percent root mass were measured at harvest. Nitrogen recovery and nitrogen use efficiency were calculated. Elevated CO₂ increased nitrogen consumption of the 100 μmol NO₃^- treatment by 13.6% and the 1000 μmol NO₃^- treatment by 21.3%. These increases were particularly evident during tillering and early grain fill. Whole plant nitrogen, shoot NO₃^-, and root NO₃^- concentrations were increased by elevated CO². High CO₂increased biomass by 15% and increased percent root mass by 11 %. Nitrogen recovery and nitrogen use efficiency were similar at both CO₂ concentrations. Transpiration (L m^-2_ground d^-1) decreased by 40% in elevated CO². The 1000 μmol NO₃^- treatment consumed more NO₃^- than did the 100 μmol NO₃^- treatment (8.1% in ambient CO₂, 15.5% in elevated CO₂); this effect was most pronounced during the last 5 days of the experiment (flag leaf emergence and early grain fill). Percent root mass increased as N concentration decreased from 1000 to 100 μmol. Nitrogen levels did not significantly affect tissue N concentration or biomass. Nitrogen losses increased as N supply increased; an average of 16% of the nitrogen added to the 100 μmol NO₃^- treatment was lost, while the 1000 μmol NO₃^- treatment lost 21%. Nitrogen use efficiency and transpiration were similar in both nitrogen treatments.

Checksum

ed14ae1b17f4fd75e91987347a59ea81

Recommended Citation

Ritchie, Karl B., "Influences of Nitrogen Supply and Elevated CO2 on Nitrogen Consumption, Nitrogen Loss, Tissue Nitrogen Concentration, and Yield of Hydroponic Wheat" (1994). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 6746.
https://digitalcommons.usu.edu/etd/6746