Effects of seed priming on the germination traits, physiological characteristics and control of cotton Rhizoctonia disease

The effects of priming with different concentrations of indole-3-acetic acid (IAA) on physiological characteristics of three cotton cultivars (Sahel, Golestan and Varamin) as well as their effects on controlling of damping-off caused by Rhizoctonia solani were investigated in two separate experiments. To determine the effects of IAA on seed germination, IAA was used at 0, 0.1, 0.01 and 0.001 μM in plastic petri dishes. In the second experiment seeds treated with 0, 0.1, 0.01, and 0.001 μM IAA grown in infested soil with R. solani inoculum. Shoot and root growth and fresh weight were evaluated 28 days after sowing and the total phenolic content of the root extract was determined by the Folin–Ciocalteu method. The results showed that seed germination, growth of shoots, roots and fresh weight increased significantly by the application of a low concentration of IAA (0.01 and 0.001 μM). The application of 0.01 and 0.001 μM of IAA also reduced disease index caused by R. solani, 17% and 38% in Sahel and 1% and 33.5% in Golestan and Varamin, respectively. The concentrations enhanced total phenolic content in defence system. Primed seeds showed a significant effect on some physiological characteristics and disease index in three different cultivars.