Abstract:
Wheat is one of the most important strategic crops in the world. However, its
production and productivity is constrained by both biotic and abiotic factors. Of the
biotic factors, wheat yellow rust is the most devastating disease of wheat. Hence,
seeking new sources of resistance is prominent to manage the disease for sustaining
wheat production. The current study was conducted to determined the response, the
sources of resistance of bread wheat genotypes against yellow rust at seedling and
adult plant stages and to evaluate the direct and indirect effects of yield components on
grain yield at Sinana and Agarfa research sites in Bale highlands for field and at
Kulumsa Agricultural Research Center for greenhouse experiment. A total of 64 bread
wheat genotypes including three checks (Boru ,Hachalu and Maddawalabu) were laid
out in a simple alpha design for field experiment. The same genotypes in the field and
universal susceptible variety (Morocco) were used in the greenhouse. The seedlings
were inoculated with five different isolates received from KARC following the standard
procedures to evaluate the tested genotypes. The analysis of variances showed highly
significant differences (P<0.001) for all traits among tested genotypes. In general, the
value of phenotypic coefficient of variation was higher than genotypic coefficient of
variation for all studied traits indicating that the higher variability existing among
wheat genotypes. Correlation analysis also showed significant associations among
tested traits at both genotypic and phenotypic level. Biomass yield and thousand
kernels weight at genotypic, and biomass yield and plant height at phenotypic level
were exerted the highest direct effect on the grain yield. There were highly significant
differences (P<0.001) among tested bread wheat genotypes for disease parameters
(final rust severity, head infection, area under disease progress curve, relative area
under disease progress curve and coefficient of infection ) at both locations. The
identified resistant genotypes at adult plant and seedling stages can be used as
resistance sources and exploited in breeding program for wheat yield improvement.
