Screening of rice varieties for Bacterial Leaf Blight under different inoculum concentrations

Abstract

Bacterial Leaf Blight (BLB) is one of the most devastating diseases in rice caused by Xanthomonas oryzae pv. oryzae. This is a growing and challenging concern in South Asian countries including Sri Lanka. BLB reduces grain production to a greater extent, by affecting panicle formation and grain filling thus resulting in a huge yield loss. The present study was carried out to screen 14 rice varieties for Bacterial Leaf Blight. Thirteen varieties received from International Rice Research Institute and one local variety; Bg94/1 were sown in 3m x 3m plots in a Randomized Complete Block Design with two replicates at Rice Research Station, Labuduwa, Galle. Rice plants at maximum tillering stage were inoculated using clipping method of artificial inoculation using 3 concentrations [undiluted and diluted; (1:1 and 1:2)] of inoculums and distilled water as a control. After 21 days, disease length of cut leaves and full length of respective healthy leaves were recorded and infection percentage was calculated. A two way ANOVA test was used to observe whether there is a significant effect of the concentration of the inoculum and the type of rice variety on the infection percentage. Out of the 14 varieties tested IR018, was graded as resistant; IR308, IR310, IR318, IR322, IR324 were found moderately resistant, while, IR043, IR050, IR306, IR316, IR319, IR321 were graded as susceptible. Further, IR301 and Bg94/1 were graded as highly susceptible at the highest inoculum concentration. Importantly, the results showed that the concentration of inoculum has significant effect (p ≤ 0.05) on diseases development. Therefore the results of the study provide useful information for breeders to develop BLB resistant varieties.