Document Type : Research Paper


1 Soil Science, College of Agriculture, Bu-Ali Sina University. Hamadan

2 Soil Science College of Agriculture, Bu-Ali Sina University. Hamadan


in the present study, the effect of various application methods of mostly applied antibiotics in agriculture (gentamicin, oxytetracycline, penicillin) at different concentration on root and shoot growth indices and number of rhizobial nodules of chickpea plant and the count of total bacteria, fungi and coliforms in soil around the plant root after a growth period of 60 days in greenhouse was evaluated as split-plot design. Application of antibiotics, even gentamicin, resulted to increase in plant shoot dry weight compared to control and the lowest weight by 0.98 g/pot observed in control treatment (without antibiotic). Root dry weight in penicillin applied treatments, specially at the higher concentration was the highest (1.1 g/pot) and was the lowest in gentamicin applied treatments, especially when applied as seed coating (0.48 g/pot). Totally, antibiotic application caused decrease in the root to shoot ratio compared to control. Application of all antibiotics increased soil bacterial count in the pots after 60 days in comparison with the control. Also, increasing the concentration of gentamicin and penicillin, decreased plant root nodule number by 78.8 and 59.7 percent, respectively. Application of antibiotics as seed coating had the highest negative impact on chickpea plant growth indices as well as rhizobial nodule numbers in plant root. Overall, the effect of antibiotics on soil microbial count and plant growth depends on antibiotic type and application method.