GROWTH, MINERAL ACQUISITION, AND WATER-USE BY MYCORRHIZAL WHEAT GROWNUNDER WATER-STRESS

Plants colonized with arbuscular mycorrhizal (AM) fungi generally have greater growth and acquisition of mineral nutrients, and often have g reater ability to withstand drought compared to nonmycorrhizal (nonAM) plants. This study determined effects of water stress (WS) versus no WS (nonWS) and the AM fungus Glomus monosporum (AM vs nonAM) on growth , acquisition of phosphorus (P), zinc (Zn), copper (Cu), manganese (Mn ), and iron (Fe), and water use in two durum wheat (Triticum durum Des f.) cultivars exhibiting differences in resistance to WS. Plants were grown on soil [low P silty clay (Typic Xerochrept, pH=8.1)] and sand m ixtures in a greenhouse. Shoot and root dry matter (DM), total root le ngth (RL), and root colonization with AM for plants grown under nonWS were higher than for plants grown under WS. Much of the reduction in D M was overcome by AM plants grown under WS. The 'drought-resistant' wh eat cultivar CR057 had higher AM root colonization than the 'drought-s ensitive' cultivar CR006 when grown with and without WS. Concentration s of P were lower and Zn, Cu, Mn, and Fe were higher in shoots of plan ts grown under WS compared to nonWS. Nutrient contents were greater in AM than in nonAM plants, and these differences were greater under WS than under nonWS conditions. The AM plants had higher water use effici ency (WUE, g DM kg(-1) water evapotranspired) values than nonAM plants when grown under WS. The cultivar CR057 generally had higher WUE-valu es than CR006. The results of this study indicated that AM plants had greater tolerance to drought stress than nonAM plants.