Temporal Progress of Sheath Blight in Irrigated Rice Genotypes as Indicative of Disease Resistance

Abstract

Rice is a major global cereal crop, which is mostly produced through irrigation systems. Fungal diseases are a threat to its production, with one of the most devastating being sheath blight, which is caused by Rhizoctonia solani. Since very few studies were conducted on the temporal dynamics of this disease in controlled irrigated rice conditions, this research was meant to determine the resistance of 18 genotypes of irrigated rice to sheath blight. The experiment was in a greenhouse on a completely randomized four-replication design. The area under the Disease Progress Curve (AUDPC) was used to assess resistance, and temporal disease progress was modeled. These genotypes showed the highest level of resistance, as indicated by the lowest AUDPC values: AB171292, AB171294, and AB171275. AB171292 was the most resistant of these, with a maximum disease severity of 9.25%. BRS Catiana, BRS A702 CL, AB171266, and AB171267 were the most susceptible genotypes, causing 75% plant death severity. The Gompertz model was most appropriate to describe the temporal disease progression of the susceptible genotypes, which follows the rapid epidemic, whereas the resistant genotypes followed the Monomolecular model, which marked the slow and restricted increase of the disease. Also, genotypes AB171307 and AB171294 possessed the highest fresh mass, which is indicative of their tolerance. The current research has determined resistant genotypes that are promising to be used in breeding programs and has also explained the epidemiology of sheath blight to manage the disease better.