Evaluation of cytogenetic effect of pesticides in onion root meristem

Farmers use chemical insecticides, fungicides and herbicides to control insect pests, diseases and weeds. Extensive use of chemical pesticides is becoming hazardous to the environment and human and animal health. Biopesticides have been used as a safer alternative. Cytogenetic analysis is needed to determine the effects of chemical and biopesticides in plants if these are used frequently in an improper concentration. This investigation assessed the effects of a chemical systemic insecticide ‘Actara 25WG’ and a bioinsecticide ‘Bio Sona’ for seed germination and on root mitosis of five onion varieties. Three concentrations of Actara 25WG were used as seed treatment, viz., 25 g, 50g (recommended) and 75 g/kg seed. Similarly, Bio Sona was applied @ 2 %, 5 % (recommended) and 8 % concentrations. Depressing effects of the two pesticides were recorded in seed germination percentage except for Bio Sona 2% in variety Bhima Shakti. Actara 25WG and Bio Sona showed either mitoenhancing or cytotoxic effects depending on dose and variety. These pesticides also induced genotoxicity at recommended and higher doses on root tip cells as indicated by the frequency of total chromosomal aberrations like binucleate cells, clumps, stickiness, disturbed stage, laggards, bridges and fragments. Bio Sona at higher concentrations showed more aberrations than Actara 25WG. There were differential responses of the varieties to the pesticide treatment. More research must be done on the effects of chemicals and biopesticides in plants to assess their cytogenotoxicity.