Differential sensitivity of barley (Hordeum vulgare L.) to chlorpyrifos and propiconazole: Morphology, cytogenetic assay and photosynthetic pigments

The present investigation was performed to evaluate the effects of an insecticide and fungicide, namely, chlorpyrifos (CP) and propiconazole (PZ) on barley (Hordeum vulgare L. variety Karan-16). The seeds were treated with three concentrations of CP and PZ, i.e., 0.05%, 0.1% and 0.5% for 6 hours after different pre-soaking durations of 7, 17 and 27 hours. Different pre-soaking durations (7, 17 and 27 h) represent three phases of the cell cycle i.e., G₁, S and G₂, respectively. Double distilled water and ethyl methane sulfonate were used as negative and positive controls, respectively. As compared to their respective controls, treated root tip meristematic cells of barley showed significant reductions in the germination percentage, seedling height, mitotic index and comparative increase in chromosomal aberrations against both the pesticides, and the magnitude was higher in CP. After treatment with the pesticides, chlorophyll and carotenoid contents increased up to 0.1% but reduced at 0.5% and the decrease was more prominent in CP as compared to PZ. In treated cells, fragmentation, stickiness, bridges, multipolar anaphase and diagonal anaphase were observed as aberrations. As compared to control, chromosomal aberrations were higher in CP as compared to PZ. The results of the present study concluded that CP induced chromosomal aberrations were more frequent than PZ; hence it has higher probability to cause genotoxicity in barley.