Impact of Stem and Yellow Rusts on Grain Yield of Bread Wheat (Triticum Aestivum L) Genotypes Under Rainfed Conditions of Ethiopia

Abstract

Plant diseases are among the major factors affecting the yield of wheat, especially rust diseases have historically been one of principal biotic production constraints in the world. Among the three main rusts affecting wheat, yellow rust, caused by Puccinia striiformis f. sp. tritici, and Stem rust caused by Puccinia graminis f. sp tritici are the most important disease in most wheat growing areas of Ethiopia. There are a limited number of resistant varieties available and new pathotypes that overcome the most widely deployed genes have arisen. The development of improved varieties of bread wheat (Triticum aestivum L.) has always remained a focal point for wheat breeders. Therefore, the purpose of this study was to select genotypes with good agronomic performance that have high grain yield and yield component with better rust resistance especially for stripe and stem rusts which are the major diseases in Ethiopia and to recommend the best genotypes to be released as new varieties and as an initial material in breeding. Twenty-Eight genotypes with two checks were evaluated in consecutive two years. From the twenty-eight tested genotypes almost all genotypes except one (ETBW9589) showed higher grain yield than the two standard checks (Kingbird and Ogolcho). But for the case of both rust diseases as AUDPC and CI showed that tested genotypes were exhibited different reaction responses, if we see one genotypes as an example ETBW9578 had the highest grain yield and good for yellow rust but as AUDPC showed it is very susceptible reaction response for stem rust. Generally phenotypic variation was observed for infection types, level of severity and reaction response for both diseases of the 28 tested elite bread wheat genotypes and the two standard checks. Reaction response for stem rust exhibited from susceptible (S) to Moderately resistance-moderately susceptible (M) and from immunity (0) to moderately resistance (MR) for the yellow rust. Around nine genotypes had good performance for all parameters; for grain yield and yield components and also for both rust diseases. The results of current study indicated that the genotypes had diversity regarding resistance reaction, ranging from complete resistance to susceptible. Most of the evaluated genotypes exhibited moderate resistance (MR) to moderately susceptible (MS) reactions under high disease pressure.