Evaluation of soybean genotypes for Asian soybean rust (Phakopsora pachyrhizi) and common bacterial blight (Pseudomonas syringae pv. glycinea) at different phenological stages in Southwestern Ethiopia

Abstract

Asian soybean rust caused by Phakopsora pachyrhizi and bacterial blight caused by Pseudomonas syringae pv. glycinea diseases are the two most limiting factors in soybean production. The use of resistant or tolerant varieties is one of the most suitable management options to control Asian soybean rust and bacterial blight. This study was carried out to evaluate the performance of soybean genotypes and to see the progress of the Asian soybean rust and bacterial blight disease over different Phenological stages of the crop. Thirty-six soybean genotypes were tested in triple lattice design. The result indicates that there was a significant (P < 0.05) difference in AUDPC value for Asian soybean rust among genotypes and genotypes by environment interaction. Mean soybean rust severity had progressively increased from 3.3% at 42 Days after sowing to 47.7% at 96 Days after sowing, while, bacterial blight severity increased progressively from seedling stage 3.4% at 29 Days after sowing to flowering stage 15.7%at 70 Days after sowing, and decreased after flowering 3.6 % at 96 Days after sowing. In this study, a total of 32 soybean genotypes showed TAN reaction while only four, genotypes showed Reddish Brown (RB) lesions. This study shows different performance of soybean genotypes against soybean rust and bacterial blight, but none of them shows immune in the future, it is recommended to evaluate large number of soybean genotypes and identifying the types of rust race is one of the key stages.