The reaction of 109 rice lines to blast disease

Blast caused by Pyricularia oryzae is the most important fungal disease of rice in the world. The best method of disease management is to identify and cultivate resistant cultivars.

In this study, the response of 109 promising lines from the Iranian Rice Research Institute along with three control cultivars (susceptible and resistant) to blast disease was evaluated. Seeds of each line were sown in an upland nursery to assess leaf blast in early July. In order to inoculate the desired lines, leaves infected with the blast were collected from different areas of Guilan Province and placed on the surface of the rice blast nursery. In all stages, the necessary humidity to cause disease was provided by sprinkler irrigation. The severity of the disease was rated from zero to nine using the standard method of the International Rice Research Institute. Seedlings were grown in large pots in the greenhouse and inoculated by injection into the panicle neck to assess panicle burst.

Seven and 14 lines with grades 2 and 3 showed resistance to leaf blast. Other lines ranged from relatively susceptible to very susceptible to the disease. Three lines TH1, TH2, and TH3 with a degree of contamination of 5 were susceptible to panicle blast disease.

Twenty-one known blast-resistant lines can be used in the rice cultivars breeding program.