Arbuscular Mycorrhizal Fungi Enhance Tolerance of<i>Rosa multiflora</i>cv. Burr to Bicarbonate in Irrigation Water

Abstract

ABSTRACT 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 (B)], 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.