Changes of root length and fresh weight in <i>Arabidopsis thaliana</i> exposed to α-, β-, γ- and δ-HCH for four weeks.

#<p>mean value ± standard deviation;</p>*<p>or ** indicate the values were significantly different as compared with controls (<i>p</i><0.05 or <i>p</i><0.01, respectively); Different letters show significant differences between values of the four HCH isomers (<i>p</i> = 0.05).