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 f rom 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 n itric acids (2:1, v/v) Or 10% NaOH to distilled water. Three experimen ts were carried out: i) seedlings growing in calcareous forest soil; i i) 2-year-old naturally mycorrhizal seedlings, transplanted into vermi culite in order to differentiate old and new-formed roots; and iii) se edlings 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 treatmen t was noted. Enhancement of ectomycorrhizae formation was also recorde d in this treatment in the three experiments. In substrata of neutro-b asic pH, short-term exposures to acid rain positively affected ectomyc orrhizal fungi, in particular, Suillus species.