Date of Award:

5-1983

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

Martyn M. Caldwell

Committee

Martyn M. Caldwell

Committee

Douglas Johnson

Committee

Ivan Palmblad

Abstract

The effect of ultraviolet-B radiation enhancement upon the competitive interactions of two species pairs was studied in the field. Wheat (Triticum aestivum L. 'Bannock') was paired with wild oat (Avena fatua L.) and jointed goatgrass (Aegilops cylindrica Host) to represent competition between species pairs in agricultural situations. Specially modulated ultraviolet lamp systems provided either low ultraviolet-B enhancement (simulation of a 16 % ozone layer reduction based upon the generalized plant action spectrum), high ultraviolet-B enhancement (40 % ozone reduction) or control (ambient solar ultraviolet-B) irradiance.

Ultraviolet-B radiation enhancement significantly altered the competitive interactions of the species pairs. However, ultraviolet-B enhancement did not affect total shoot biomass production in the mixtures or shoot biomass production of the species in monoculture. The direction in which competitive interactions were altered appeared to be dependent upon the time at which the seeds were planted. Also, water stress affected some aspects of the interaction between ultraviolet-B enhancement and plant competition but the manner of this effect was inconsistent. Reproductive effort of the species was generally not affected by ultraviolet-B enhancement, except in wild oat plants under interspecific competition.

Checksum

77dbe8831ab0cd746f579f9c8414f0d7

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .