PHYSIOLOGICAL-RESPONSES OF 6 WHEATGRASS CULTIVARS TO MYCORRHIZAE

The physiological and morphological responses of 6 wheatgrass (Agropyron) cultivars to vesicular-arbuscular mycorrhizal inoculation were measured in the greenhouse. These included diploid, tetraploid, and hexaploid cultivars. Plants had up to 94% infection after 4 months. The 2 diploid cultivars (A. cristatum cv. 'Fairway' and A. cristatum ssp. puberulum) formed infection most rapidly, and they also had significantly reduced root biomass and higher water use efficiency with infection. A hexaploid cultivar (A. cristatum from U.S.S.R.) produced significantly more tillers with inoculation, while the tetraploid A. desertorum cv. 'Nordan' had fewer tillers and wider leaves. Inoculation increased leaf phosphorus concentration in 4 of the 6 cultivars. Carbon dioxide gas exchange rate, transpiration rate, stomatal resistance, and N concentration were not significantly affected by mycorrhizal inoculation for any of the cultivars. The cultivar Nordan had the greatest number of physiological and morphological increases in response to mycorrhizal infection, while A. cristatum from Iran (hexaploid) performed most poorly in that it had reduced WUE and no apparent beneficial responses to infection. There was no relationship between ploidy level and mychorrhizal response.