Controlling seed rot and seedling damping-off in vicia faba caused by Rhizoctonia solani using resistant cultivars and biological agents in Iraq

Abstract

The study aimed to implement one of the integrated management strategies in controlling the seed rot and seedling damping-off disease of faba bean caused by the fungus Rizoctonia solani, using plant cultivars and some environmentally friendly agents. The isolation and identification results showed that 12 fungal isolates associated with the seedling damping-off disease belong to the genus       Rhizoctonia spp., eight isolates of the fungus F. solani, six isolates of the fungus F. oxysporum, and six isolates of the fungus Macrophomina spp., and others. The pathogenicity test results showed that all fungal isolates were pathogenic. However, the percentage of seed germination inhibition, seedling death, and symptoms appeared varied. The isolate K.h.R1 of the fungus Rizoctonia sp. was outperformed in its virulence, as its infection Percentage to100%. This was molecularly identified as R.solani under the deposit number PV939284.1 in NCBI.Meanwhile, the results of the field experiment showed that all treatments used to control the disease caused by the pathogenic fungus R. solani were effective in controlling the disease; the integrated treatment of factors (Azotobacter chrocoocum, salicylic acid, and Zinc) was significantly outperformed in reducing the infection percentage and severity of 41.66% and 18.11%, respectively, compared to the pathogen-only treatment of 96.67% and 85.86%,   respectively. By increasing the activity of the enzymes peroxidase and polyphenol oxidase and raising the total phenolic content, the integrated treatment (SA + Zn + Azo) also clearly contributed to the development of systemic resistance in the plant against the pathogenic agent. Furthermore, the plant cultivar response results revealed that the Cypriot cultivar performed significantly better than the others in terms of disease resistance, registering the lowest levels of infection and severity with mean values of 49.33% and 39.09%, respectively, in contrast to the Syrian cultivar, which recorded 66.66% and 56.15%, respectively.