Interaction between BSM-contaminated soils and Italian ryegrass

Abstract

The interaction among the bensulfuron-methyl, growth of Italian ryegrass, and soil chemical/biochemical/microbiological parameters was investigated in a microcosm experiment. The bensulfuron-methyl added to the soil can be rapidly degraded by certain fungi and actinomycetes present in the original paddy rice soil. The growth of Italian ryegrass significantly accelerated the in-soil degradation of bensulfuron-methyl in its rhizosphere. The uptake of bensulfuron-methyl by ryegrass increased with increasing dosage level of bensulfuron-methyl. However, the phytoextraction of bensulfuron-methyl by ryegrass contributed insignificantly to the total removal of the soil bensulfuron-methyl. Within the dosage range set in this study, the root development of ryegrass was not adversely affected by the presence of the soil bensulfuron-methyl although the fresh biomass of shoot was slightly reduced in the higher dosage treatments. This can be attributed to the adsorption of the added bensulfuron-methyl by soil colloids and consequently the reduction of bensulfuron-methyl level in the soil pore water to a concentration sufficiently lower than the toxic level. The growth of ryegrass significantly increased soil pH and the activities of phosphatase and peroxidase but reduced the EC and the activities of urease in the rhizospheric soil.

Keywords:

• Bensulfuron-methyl
• Italian ryegrass
• soil
• paddy rice
• degradation
• rhizosphere

Acknowledgments

The work related to this article was financially supported by the Major State Basic Research Development Program (973) of China (Project No. 2006CB100206) and the Natural Science Foundation of China (Project No. 30670380 and Project No. 30870413). The authors would like to thank Dr. Phillip Ford for reading the revised manuscript and making constructive comments that help us to improve the presentation of this article.