Date of Award:

5-1988

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

Edith B. Allen

Committee

Edith B. Allen

Committee

M. F. Allen

Committee

N. E. West

Abstract

Physiological and morphological responses of six Agropyron cultivars to vesicular arbuscular mycorrhizal (VAM) inoculation were measured in the greenhouse. These included diploid, tetraploid, and hexaploid cultivars. Plants had up to 94% infection after three months. The two diploid cultivars (A. cristatum (Fairway) and A. puberulum) had the fastest rate of infection. With VAM infection the two diploid cultivars were significantly reduced in rood biomass and had lower water use efficiency than without infection. Phosphorus concentration of mycorrhizal plants was significantly higher in shoots of four or the six cultivars. Carbon dioxide gas exchange rate, transpiration rate, stomatal resistance and N concentration were the same for the two treatments for all six cultivars. One cultivar (A. cristatum from U.S.S.R., a hexaploid cultivar) produced a significantly higher number of tillers with VAM. Agropyron desertorum (Nordan, tetraploid) was the only cultivar showing an increased leaf width, combined with a decrease in tiller number with VAM inoculation. The hybrid A. cristatum X desertorum (Hycrest, tetraploid) and the two hexaploid cultivars had the most positive response to VAM infection among the six cultivars. The two diploid cultivars (Fairway and A. puberulum) had the most negative response to VAM infection.

Mycorrhizal spore counts and percent root infection of dominant species were assessed in different vegetation types and different disturbances in Curlew Valley. Both were very low during fall 1986 and summer 1987, so no conclusions can be made about the effects of vegetation and management on mycorrhizal abundance at this site. However, the Agropyron cultivars had 25-38% infection at Evan's Farm, so mycorrhizae are hypothesized to be important for their growth in the field at some sites and during some years. The combined field and greenhouse data suggest that plant breeders need to take mycorrhizae into consideration in their selection programs.

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