EFFECTS OF SIMULATED ACID-RAIN ON POLLEN PHYSIOLOGY AND ULTRASTRUCTURE IN THE APPLE

Viability, germination and tube length were investigated in pollen gra ins of field-grown 'Summerred' apple trees (Malus domestica Borkh) exp osed to deionized water, rainfall or simulated acid rain at pH 5.6, 4. 0 and 3.0. Fallen viability and germination significantly decreased wi th lower values of pH and with increasing number of treatments. The ef fects of pH 5.6 and natural rainfall were not significant. Electron mi croscope investigation of vegetative pollen cells of plants exposed to acid rain at pH 4.0 and 3.0 showed modified features in mitochondria, plastids and endoplasmic reticulum. (C) 1997 Elsevier Science Ltd.