Study of the effect of the bacteria "Azotobacter chroococcum" in protection of seeds and seedlings of sunflower (Helianthus annuus L.)

Abstract

This study was conducted during the 2012-2013 growing season, at the College of Agriculture-Kerbala University, to evaluate the efficiency of the chemofungicide "Beltanol" and the biological control bacteria "Azotobacter chroococcum" to control seed decay and seedling damping-off disease caused by Rhizoctonia solani and Fusarium solani in sunflower. Laboratory results showed that the R. solani fungus was more incident than Fusarium solani in the infected sunflower plant samples collected from the agricultural fields. It was noted that R. solani had the most impact in reducing seed germination percentage (%16.70) that was significantly differed from the control treatment.

Results also revealed that the Beltanol chemofungicide applied at a concentration of 1 ml/ 1 L PDA medium was highly effective in inhibiting the fungal growth. A. chroococcum was also efficient in reducing mean radial growth of R. solani that reached 2.40 cm. These results were significantly different from the results obtained from the control treatment containing R. solani alone.

From the plastic house experiment, it was found that treating with A. chroococcum   had an effective role in protecting seeds and seedlings from infection with R. solani that led to increase seeds germination to 63.30% and reduce the severity of infection as well as improve the mean of plant length (19.67%). This treatment was significantly different from the control treatment containing R. solani alone that led to an obvious reduction in seed germination percentage, infection severity and plant length that reached 33.30%, 93.00 and 8.67 cm, respectively.