R. Dragov*, D. Dechev

Field Crops Institute, 6200 Chirpan, Bulgaria

Abstract. The yield is a key indicator in the plant breeding of crops. In recent years a number of new durum wheat varieties created in Field Crops Institute, Chirpan, Bulgaria, have been certified, which are prerequisites for the variety`s change in our country. The establishment of phenotypic stability of yield in the new varieties and advanced lines is of great importance if the interaction between genotype and environment has significant influence on the yield variation. This study includes 20 of our varieties and durum wheat lines to establish their phenotypic stability in yield. The experiment was conducted in the period 2011 – 2013, on the fields of Field Crops Institute, Chirpan based on the standard technology of growing crops. Genotypes were tested in randomized block design with four repetitions and size of harvested plot of 15 m2. For the valuation of phenotypic stability parameters of Shukla (1972) are used – σ 2 and s2 ecovalence, of Wricke (1962) – w2 and the parameter for the yield and stability of Kang (1993) YS . Also, PC – analysis and cluster analysis are used. The analysis of variance shows significant values to the variation of genotypes, environments and interaction between both factors, which allows us to identify the yield phenotypic stability of each participant in the experiment. The result of the study demonstrated significant interaction between genotypes and conditions of the year for yield. From the calculated parameters of stability the new lines D-7557, D-7877, M-6433, E-7724 and M-334 are the most promising for the breeding. They are characterized with high grain yield and good phenotypic stability. Our results reveal the opportunities to use some multivariate statistical methods (PC and cluster analysis) for assessment of yield stability.