Pathogenicity and yield loss assessment caused byMagnaporthe oryzaeisolates in cultivated and wild relatives of finger millet (Eleusine coracana)

Abstract

Magnaporthe oryzae, a fungal pathogen that attacks more than 50 gramineous species, causes severe yield losses particularly on rice and finger millet. A study was conducted at Bako Agricultural Research Center in Ethiopia during the 2012 cropping season to evaluate the pathogenicity of four different finger millet blast isolates on 12 cultivated finger millet accessions and 4 of its wild relatives (Eleusine coracana subsp. africana). A split plot design, replicated three times, was used. Test accessions showed significant difference (Pd”0.01) but the isolates and genotype by isolate interaction showed no significant differences for grain yield. Pathogenicity tests revealed that isolates Pg. 11 and Pg. 22, isolated from neck and head of finger millet, respectively, were most virulent in infecting all plant tissues. The isolate from neck of the wild type (Pg. 41), infected both the cultivated and its wild types, confirming that wild types or weeds can act as hosts or reservoirs of the pathogen and source of inoculum. The mean grain yield per plant was lower for isolate Pg.22 (2.8g) and Pg.11 (2.9g) but relatively better for Pg.41 (3.6g) and Pg.26 (3.1g), indicating the inverse correlation between infection severity and grain yield. Finger millet accessions such as Acc. 214995 and PW-001-022 recorded lower blast infection consistently during 2011 and 2012 and are thus potential candidates for further evaluation in variety development activities. Among the wild accessions, AAU-ELU-15 showed the least blast infection. Mean yield loss assessment results from 2011 and 2012 field experiments calculated using Relative Area Under Progress Curve (RAUDPC) and multiple point models, respectively, revealed an average of 42% grain yield lost due to blast disease.