RESPONSE OF BREAD WHEAT (Triticum aestivum L.) GENOTYPES TO YELLOW RUST (Puccinia striiformis f. sp. tritici) AT SEEDLING AND ADULT PLANT STAGES IN BALE HIGHLANDS, SOUTHEASTERN ETHIOPIA

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.