Mycorrhizae, Soil Amendments, Water Relations and Growth of Rosa multiflora under Reduced Irrigation Regimes

by F.T. Davies, Jr., Y. Castro-Jimenez and S.A. Duray

To determine the role of endomycorrhizae and selected soil amendment treatments on water relations and growth of Rosa multiflora, rooted cuttings were planted in a medium with either incorporated hydrogel (polyethylene oxide) or a synthetic mulch surface covering (wax-impregnated cardboard ) and either inoculated with vesicular-arbuscular mycorrhizal fungi (VAM) [ Glomus mosseae ( Nicol. And Gerd. ) and G. Fasciculatum (Thaxt. Sensu Gerd. ) Gerd and Trappe] or left as non-inoculated controls. Plants were initially irrigated daily, but then irrigation was reduced to three times weekly before water-stress cycles were initiated. Shoot and root dry weight and root:shoot ratio were higher when hydrogel was incorporated in the medium, regardless of VAM colonization treatments. Xylem water potential in shoots ( ) of roses with hydrogel-incorporated medium was lowest (more negative) and had the greatest changes regardless of mycorrhizal treatment. In general, mycorrhizal plants had lower transpirational rates and a higher diffusive resistance, either with or without hydrogel incorporation in medium.

Scientia Horticulturae, 33 (1987) 261-267.