Abstract: A simulation test was conducted to study the biodegradation of aromati c hydrocarbons (phenanthrene and anthracene) and aliphatic hydrocarbon (n-hexad ecane) by indigenous microorganisms when the test hydrocarbons were existed indi vidually or in coexistence in soil. The results indicated that the biodegradatio n of test hydrocarbons followed first-order kinetics. The biodegradation rate c onstant of phenanthrene, anthracene, and n-hexadecane existed individually in s oil was 00283, 00226 and 00096 d-1, respectively. When co-existed with phenanthrene, n-hexadecane could serve as a co-metabolic substrate and pr omote the biodegradation of phenanthrene, making the half life of phenanthrene r educed by 44%, comparing with that when phenanthrene existed individually. In th e meanwhile, n-hexadecane oxygenase was induced by phenanthrene. The increase o f the induced oxygenase activity promoted the degradation of n-hexadecane, and reduced the half life of n-hexadecane by 49%, comparing with that when n-hexad ecane existed individually. Contrarily, the coexistence of phenanthrene and anth racene promoted the biodegradation of phenanthrene but inhibited that of anthrac ene.

Key words: Allelopathy, Root exudates, Eggplant, Graft, Autotoxicity