Effect of Exudates from Ryegrass Roots on Organochlorine Degradation by Rhizospheric Microbes

Pot experiments were conducted to investigate effect of the exudates from roots of ryegrass (Lolium multiforum) on microbial degradation of organochlorine pesticide(OCP) residues in rhizospheric soil. The results showed that, within the tested concentrations of 0-343.61 mg·kg^-1, the exudates exhibited a significant enhancement on OCPs degradation in the soil. And, the highest OCPs removal rate at 77.57% was achieved when the root exudates were added in the presence of rhizospheric microbes; whereas, without the exudates, the removal rate was merely 33.49%, and it was 58.16% in the soil spiked with 0.05% NaN₃ to suppress the microbial effect.Furthermore, under a same level of the pesticide stress, the microflora population increased with increasing exudates concentration in the soil suggesting that phytoremediation of the ryegrass under stress might also encourage the growth and metabolism of the rhizospheric microbes leading to the improved OCPs degradation.