Screening of rice (Oryza sativa L.) cultivars for resistance against the grain discolouration disease complex

Abstract

Grain discolouration is an emerging complex fungal disease of rice affecting the rice glume and kernel. Recently, it has become a severe menace throughout India, affecting the grain quality and yield. Hence, there is an urgent need to identify the resistance source and devise standard integrated management practices. Given this scenario, a pot culture experiment was conducted in a glasshouse to screen Kerala Agricultural University (KAU) released seventeen rice varieties, namely, Bhadra, Asha, Karthika, Aruna, Makom, Pavithra, Panchami, Uma, Karishma, Krishnanjana, Gouri, Prathyasa, Shreyas, Pournami, Athira, Matta Triveni and Annapoorna for resistance against grain discolouration disease of rice. The statistical design followed was a completely randomised design (CRD) with seventeen treatments (varieties) and three replications. Artificial inoculation was done at the booting stage of the crop using the spore suspension injection method. Resistance levels among the varieties were evaluated based on the estimated disease parameters such as percent panicle infection (disease incidence), spikelet infection, grain discolouration and percent disease index (disease severity). Among the assessed disease parameters, the highest grain discolouration (59.39 %) and disease severity (56.39 %) were observed in the case of the susceptible check, Uma. The lowest grain discolouration (17.18 %) and disease severity (25.69 %) were observed in the case of the moderately susceptible variety, Shreyas (MO 22). None of the varieties came out to be immune or resistant. The entire study revealed that varieties, MO 22 (Shreyas) and MO 21 (Prathyasa), were moderately susceptible and the rest were susceptible or highly susceptible.