Arbuscular mycorrhizal fungi enhance tolerance of Rosa multiflora cv. burr to bicarbonate in irrigation water

High bicarbonate (HCO3-) of irrigation water can be detrimental to plant growth in sustainable horticultural production systems. The ability of arbuscular mycorrhizal fungi (AMF), ZAC-19, (composed of Glomus albidum, Glomus claroideum, and Glomus diaphanum) to enhance tolerance to HCO3- was tested on Rosa multiflora cv. Burr. Arbuscular mycorrhizal colonized and non-inoculated (non-AMF) plants were treated with 0, 2.5, 5, and 10 mM HCO3-. Increasing HCO3- concentration and associated high pH and electrical conductivity (EC) - reduced plant growth, nutrient uptake, and acid phosphatase activity, while increasing alkaline phosphatase activity (ALP). Inoculation with AMF enhanced plant tolerance to HCO3-, as indicated by greater growth (leaf, stem, and total plant dry weight, leaf area and leaf area ratio), leaf elemental concentration [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), iron (Fe), zinc (Zn), aluminum (Al), boron (13)], leaf chlorophyll concentration, higher mycorrhizal inoculation effect, lower root Fe reductase activity, and generally lower soluble ALP activity. While AMF colonization was reduced by increasing HCO3- concentration, colonization still occurred at high HCO3- concentration. At 2.5 mM HCO3-, AMF plant growth was comparable to plants at 0 mM HCO3-, further indicating the beneficial effect of AMF for alleviation of HCO3- plant stress.