Abstract:

This study investigated the carbohydrates and their metabolic enzymes to research the effects of acid precipitation (pH 6.0、4.0、3.0、2.0) and Al (theoretical concentrations were 75, 150 μmol·L^-1) on the sugar accumulation and transportation in Pinus massoniana with and without inoculating mycorrhizal fungus Pisolithus tinctorius. The results revealed that the acid precipitation and Al inhibited the chlorophyll and dry weights, between whom the great positive correlation (r=0.949) existed. The contents of soluble sugars decreased in leaves; the light acid precipitation induced sugar accumulation in the roots and stems, but the strong acid precipitation inhibited it; the acid precipitation and Al prevented the sugars transporting down to the roots. The trehalose accumulation was inhibited by the acid precipitation in mycorrhizal roots under the low Al stress, but it was induced under the high Al stress, which showed negative correlation with the activities of trehalase (r=-0.857). The light acid precipitation induced glucose accumulation in the roots, stems and leaves, but the strong acid precipitation inhibited it. The activities of glucose-6-phosphate dehydrogenase and trehalase were induced by the low Al stress, but they were obviously inhibited by the high Al stress. Inoculating mycorrhizal fungus at the roots induced the dry weights, prevented the sugars transforming into glucoses.

Key words: acid precipitation, Al, Pinus massoniana, Pisolithus tinctorius, carbon metabolism