Seven day-old non-AM-infected trifoliate orange [Poncirus trifoliata (L.) Raf.] seedlings were used in this study. Six seedlings were grown in a plastic pot (15 × 20 cm) containing 3.37 kg of autoclaved growth substrate (soil:vermiculite:sphagnum, 5:2:1, v/v/v). The substrate had a pH of 5.9, 1.3% organic matter, 30 mg/kg available phosphorus, 147 mg/kg alkali hydrolysable nitrogen, and 141 mg/kg available potassium. Half of the pots received Glomus versiforme (Karsten) Berch (30 g of inoculum placed 5 cm deep) at transplanting. This inoculum contained approximately 2,233 spores and was provided by the Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences. Control treatment received no AMF inoculum (30 g of autoclaved growth substrate). The AM and non-AM seedlings were placed in a greenhouse without temperature control from March to September 2004.All seedlings were watered daily until differential water treatments were initiated 97 days after transplanting. Pots with WW and DS seedlings were maintained everyday at 75% (corresponding to -0.09 MPa) or 55% (corresponding to -0.40 MPa) relative soil-water content by gravimetry, respectively.The experiment was laid out in randomized complete blocks with two water treatment (WW and DS) and two mycorrhizal treatment (G. versiforme and non-AMF). Each of the four treatments had six replicates.

AMF colonization enhances osmotic solute accumulation of trifoliate orange seedlings, thus providing better osmotic adjustment in AMF seedlings, which did not correlate with proline but with K^{+, Ca2+, Mg2+, glucose, fructose and sucrose accumulation.}