Asian Journal of Biology

The increasing use of Di-Ammonium Phosphate (DAP) fertilizer is mainly due to its high nitrogen and phosphorus content, which promotes plant growth and agricultural productivity. However, excessive and prolonged use of DAP may adversely affect soil fertility and induce cytotoxic effects in living organisms. Therefore, the present study was conducted to evaluate the cytotoxic effects of DAP on Allium cepa (onion) root tip cells. Three concentrations of DAP, namely 0.4 g/L, 0.8 g/L, and 2.0 g/L, were used for treatment, while untreated roots served as the control group. The root tip cells were exposed to the treatments for 96 hours. The mitotic index decreased from 15.21 ± 0.77 in the control group to 13.63 ± 1.38, 9.60 ± 0.70, and 4.80 ± 0.40 with increasing concentrations of DAP, indicating a concentration-dependent inhibition of cell division. The frequency of chromosomal abnormalities also increased with increasing DAP concentration. The most common abnormalities observed were multipolar spindle formation, laggard chromosomes, anaphase bridges, and polyploidy. The findings indicate that prolonged exposure to higher concentrations of DAP induces significant cytotoxic effects in Allium cepa root meristem cells and may interfere with normal mitotic activity and chromosomal behavior.