ALLELOPATHIC EFFECTS OF FESCUE ON THE GROWTH OF SWEETGUM

The height growth of field-planted sweetgum (Liquidambar styraciflua L.) seedlings was reduced where residual rescue (Festuea arundinacea Shreb. Vat. Ky. 31) from previous agricultural experimentation was present. Interference (competition+allelopathy) effects of fescue on the growth of sweetgum were tested in the greenhouse. Fescue seeded into pots containing sweetgum seedlings resulted in dry weight reduction of sweetgum from 29 to 95%. Elimination of the competitive effect through the use of a stairstep apparatus implicated an allelopathic mechanism in the interference of sweetgum growth by fescue. Leachates from the rhizosphere of live rescue, dead rescue roots, and dead fescue leaves resulted in reduction up to 60% in dry matter production of sweetgum seedlings. Chemical analysis of sweetgum seedlings from the stairstep experiment suggested impaired adsorption of phosphorus and nitrogen by seedlings treated with fescue leachates.