The investigation of genotoxic, physiological and anatomical effects of paraquat herbicide on Allium cepa L. (onion)

The aim of this study was to investigate the toxic effects of different doses of Paraquat treatment on Allium cepa L. Germination percentage (GP), root length (RL), weight gain (WG), micronucleus (MN) frequency, chromosomal aberrations (CAs) and changes of root anatomy (RA) were used as indicators of toxicity, and these data were correlated with statistical parameters. The seeds were divided into four (4) groups; one (1) as control and three (3) as Paraquat treatment groups. Treatment groups were treated with 10, 50 and 100 ppm doses of Paraquat during 72 hours. The results indicated that there was an alteration in the germination percentage (GP), root length (RL), weight gain (WG), chromosomal aberrations (CAs), micronucleus (MN) frequency and changes of root anatomy (RA) depending on the treatment dose in the seeds exposed to Paraquat when compared with the controls. Increasing dose of Paraquat significantly reduced the germination percentage (GP), root length (RL) and weight gain (WG) in seeds of all the treatment groups. The highest germination percentage (GP), root length (RL) and weight gain (WG) were observed in seeds of the control group. Besides, Paraquat caused a dose-dependent increase in the frequency of MN and chromosomal aberrations (CAs). In treatment groups, the highest frequency of MN and chromosomal aberrations (CAs) was observed at 100 ppm dose of Paraquat and the lowest frequency of MN and chromosomal aberrations (CAs) was observed at 10 ppm dose of Paraquat. Paraquat treatment caused anatomical alterations on root tips when compared with the controls and rate of anatomical alterations increased with increasing dose of Paraquat. The results of the present study indicate that Paraquat herbicide has toxic effects on Allium cepa L. root tip cells, and the selected parameters such as the Germination percentage (GP), root length (RL), weight gain (WG), micronucleus (MN) frequency, chromosomal aberrations (CAs) and changes of root anatomy (RA) are very sensitive and useful biomarkers for biomonitoring these effects.