EVALUATION OF SOME SELECTED RICE CULTIVARS AGAINST THEIR MAJOR DISEASES UNDER NATURAL FIELD CONDITION

Abstract

A field experiment was carried out to evaluate some selected rice varieties against their major diseases under natural field condition in the field of Plant Pathology Department, Hajee Mohammad Danesh Science and Technology University, Dinajpur during the aman season of 2022-2023. Five rice varieties namely BR-34, Paijam, Malshira, Badshahbhog and Philippinekatari were evaluated regarding disease incidence and severity and the effect of diseases on yield and yield contributing characters. Five diseases namely brown spot (Bipolaris oryzae), sheath blight (Rhizoctonia solani), leaf blast (Pyricularia oryzae), bacterial leaf blight (BLB) (Xanthomonas oryzae), and sheath rot (Sarocladium oryzae) were recorded and pathogens identified. The disease incidence and severity of brown spot were recorded from 0.42% to 10.22% and 0.04% to 3.29% (0-9 scale), respectively where Philippinekatari showed the highest incidence (10.22%) and severity (3.29%), and Malshira showed the lowest incidence (0.42%) and severity (0.04%). In case of sheath blight, the disease incidence and severity ranged from 0.66% to 9.76% and 0.09% to 1.19% (0-9 scale), respectively where Badshahbhog showed the highest disease incidence (9.76%) and severity (1.19%) and Badshahbhog and Malshira showed better result against the disease. Disease incidence and severity of leaf blast varied from 0.13% to 1.62% and no disease was obtained in Badshahbhog and Paijam (0.00%) at 30 DAT (0-9 scale), respectively where Philippinekatari showed the highest incidence (1.62%) and severity (0.23%), and Badshahbhog and Paijam showed better result against the disease. In case of bacterial leaf blight, the disease incidence and severity ranged from 0.12% to 3.96% and 0.04% to 1.65% (0-9 scale), where BR-34 showed the highest incidence (3.96%) and Paijam showed the highest severity (1.65%) and Paijam and Badshahbhog showed the better result against the disease. The disease incidence and severity of sheath rot varied from 0.49% to 6.02% and 0.03% to 1.24% (0-9 scale), where BR-34 showed the highest incidence (6.02%) and severity (1.24%) and the lowest incidence (0.49%) and severity (0.03%) observed on Paijam. The highest growth and yield contributing characters recorded on Badshahbhog, Paijam and Malshira considering plant height, number of tillers, number of leases, and panicle length. The highest grain yield (4.05 t/ha) found in Paijam and the lowest grain yield was observed in Philippinekatari (2.14 t/ha) and Badshahbhog (2.87 t/ha). It was observed that disease incidence and severity was gradually increased wit