Negative Effects of Residual Herbicides on Sensitive Crops: Impact of Rimsulfuron Herbicide Soil Residue on Sugar beet

This study was designed to assess the effect of rimsulfuron soil residues (۰, ۰.۱۱, ۰.۵۸, ۱.۱, ۲.۴, ۳.۶ and ۵.۸ μg a.i. kg−۱soil) on sugar beet (Beta vulgaris L.) plant with bioassay method. Plant response of roots and shoot dry weight per pot were described by A log-logistic model using R software as a function of rimsulfuron doses logarithm by non-linear regression and used to calculate the doses for ۱۰, ۵۰ and ۹۰% inhibition of plant root and shoot dry weight (ED۱۰, ED۵۰ and ED۹۰). Sugar beet was susceptible to rimsulfuron soil residues in all concentrations and biomass loses increased linearly as the concentration of rimsulfuron increased in the soil up to ۰.۱۱ µg/kg soil. The root biomass was more sensitive than shoot biomass where the ED۵۰ calculated for root and shoot biomass was ۰.۱۲۳ and ۰.۲۰۲ µg. kg-۱ soil, respectively. The same results were obtained for ED۱۰ and ED۹۰. From the results of the study, it is concluded that sugar beet is very sensitive and suitable species for using as a bio indicator in bioassay experiments for determine the side-effects of rimsulfuron at low concentration rates. By determining the concentration of rimsulfuron soil residues and the side-effect on sensitive crops, the agricultural managers could have some flexibility in crop rotations program if sensitive crop such as sugar beet is to be planted in the field that previously treated with sulfonylurea herbicides.

Keywords:

Inhibition , phytotoxic , rotation , Sensitivity , side-effect