ICOM1 Abstract

Diaz, Gisela1 & Mario Honrubia1. Departamento de Biologia Vegetal (Botanica). Facultad de Biologia. Universidad de Murcia. Campus de Espinardo 30100, Murcia. Spain.- Effect of simulated acid rain on mycorrhizae of Aleppo pine (Pinus halepensis Miller ) in calcareous soil Mycorrhiza formation and plant growth, in particular root development, of Pinus halepensis were studied in relation to the influence of pH from simulated rain in pot cultures. Four treatments of water (7.5, 6.0, 4.5 and 3.0) were established by adding a mixture of sulphuric and nitric acids (2:1, v/v) or 10% NaOH to distilled water. Three experiments, that differed in the inoculation treatment, type of substrate and age of seedlings, were carried out: 1) Three-month-old seedlings growing in untreated calcareous forest soil; 2) two-year-old naturally mycorhizal seedlings, transplanted into vermiculite in order to differentiate old and new-formed roots; and 3) seedlings growing in peat-vermiculite, inoculated with mycelial inoculum of Suillus collinitus. Although no visible effects on the aerial part were observed, a reduction of root length in the most acidic treatment was noted.The dominant morphotype observed in experiments 1 and 2 was of the Suillus kind. Enhancement of ectomycorrhizae formation was also recorded in this treatment in the three experiments. In conclusion, in substrata of neutro-basic pH, short-term exposures to acid rain positively affected ectomycorrhizal fungi, in particular, Suillus species.