Partial Resistance Components and Morphological Traits Aid Selection of Resistant Wheat Genotypes against Spot Blotch

Abstract

Spot blotch caused by Bipolaris sorokiniana results substantial yield losses (15-80%) in an Indian subcontinent. Wheat varietal improvement through breeding followed by evaluation of elite germplasms against a particular disease is crucial method to manage diseases. Fifty diverse wheat genotypes and two susceptible checks viz., Sonalika and Nepal 297 were evaluated under artificial epiphytotic condition against spot blotch at NWRP, Bhairahawa, Nepal in 2017-18 and 2018-19. Evaluation was based on partial resistance components viz., lesion sizes, lesion types (chlorotic/ necrotic), lesion characteristics (sporulating/ non-sporulating) and area under disease progress curve (AUDPC) and morphological traits viz. lesion mimic, leaf angle, leaf tip necrosis and plant height. Statistical analysis revealed that genotypes with smaller lesion size (<1 cm), small dark brown to black lesions with or without chlorosis/ necrosis and non sporulating lesions had lower AUDPC (<225). Similarly genotypes with erect to semi erect leaf (leaf angle 1-2), medium to high leaf tip necrosis (2-4), low percentage of lesion mimic (0-22.5%) were found resistant (AUDPC<225) to moderately resistant (AUDPC value 226-315). Moreover AUDPC showed strong and positive correlation with lesion sizes (0.76), lesion types (0.84) and lesion characteristics (0.54). Twenty genotypes were found resistant (AUDPC<225), could be used as new resistance sources in breeding program. However genotypes viz., KACHU/BECARD//WBLL1*2/BRAMBLING/3/ATTILA*2/PBW65//MURGA, FRET2*2/SHAMA//TNMU/3/FRET2*2/SHAMA/4/UP2338*2/KKTS*2//YANAC/5/FRET2*2/SHAMA//PARUS/3/FRET2*2/KUKUNA, KACHU#1//PI610750/SASIA/3/KACHU/4/MUU#1//PBW343*2/KUKUNA/3/MUU/5/KACHU#1//PI610750/SASIA/3/KACHU, BORL14//KFA/2*KACHU and KFA/2*KACHU//QUELEA were found excellent based on partial resistance components and morphological traits. These genotypes could be further evaluated for yield potential in multi environment and better performing genotypes could be released as resistant varieties for spot blotch.