Field and greenhouse inoculation methods for assessment of sheath blight resistance in rice

Abstract

Field and greenhouse inoculation methods were compared to determine the genetic variation for resistance to Rhizoctonia solani in 38 somaclones of rice cultivar Metica-1. Rice plants in pots were inoculated with isolate 4F1 at the age of sixty four days, with 2.0 g of the fungal culture, multiplied on rice grain and hull medium and placed on the soil surface around the plant. The differences among somaclones in relation to lesion height were significant and varied from 6.5 to 15.5 cm. In the field trial of artificial inoculation with fungal culture, 52 days after planting, the lesion height varied from 6.2 to 17.7 cm. The correlation between disease severity in the greenhouse and the field was positive and highly significant (r=0.44; P< 0.01), indicating the greenhouse inoculation as a safe method for screening germplasm for sheath blight resistance.