Mineral nutrition of mycorrhized seedlings of a tropical gum tree in copper contaminated soil

Abstract

Extensive use of such fungicides leads to Cu diffusion in most soils and increases risk of Cu phytotoxicity for the tropical gum tree  (Sterculia setigera) grown in these soils. A pot experiment was set to examine the effect of Arbuscular Mycorrhizal Fungus (AMF),  Rhizophagus fasciculatus, and soil copper levels content on mineral status of the tropical gum tree Sterculia setigera. Plants were grown  in soil with different Cu levels (0, 200, 400, 600 and 800 mg.kg^-1 ). Control plants (C) were found to have survival rate were of 40% at 600  mg.kg-1 Cu. Inoculated plants (T) on their part had a survival rate of 100% on Cu contaminated soils up to 600 mg.kg^-1 Cu. However, at  800 mg.kg^-1 Cu level, 100% of the plants died. Root colonization rates (7.4%) were significantly lower at 600 mg.kg^-1 Cu. In contaminated  soil, higher mycorrhizal colonization was measured at 0, 200, and 400 mg.kg-1Cu addition levels. AMF-inoculated plants had higher K, P,  N, Ca, Mg and Cu concentrations than uninoculated plants. In mycorrhized plants, nutrient concentrations increased with the increasing  levels of soil Cu and were higher than those of the non-mycorrhized plants. Unlike Na, the uptake of K increased in shoot tissues of  mycorrhizal plants with the increasing levels of Cu. Results suggested that S. setigera associated with AM fungus Rhizophagus  fasciculatus had the potential to survive and to grow under moderately Cu contaminated soil system.