Partitioning of genotype & environment interactions to change in rankand change in value parts in oat (Avena sativa L.) genotypes

This research was conducted to evaluate genotype × environment interaction effects for grain yield of four Canadian cultivars and five Turkish breeding lines of oats، and to determine yield stability and partitioning of genotype × environment interaction to change in rank and change in value parts. Evaluating environments consisted of 3 planting dates of 12 Oct.، 31 Oct. and 21 Nov. and 3 sowing densities of 300، 375، 450 seed / m2. The experiment was conducted in Experimental Field of Isfahan University of Technology at 2000-2001through a randomized complete block design with 3 replications each environment. Combined analysis of variance for yield showed highly significant (P<0. 01) differences among genotypes. Significant (P<0. 05) differences were observed among environments for grain yield. Genotype responded differently to environmental conditions and therefore significant genotype × environment interaction was detected. The ratio of genotype × environment interaction sum of square to total sum of square for grain yield (22. 37%) was higher than other traits. Wrick equivalence and Shukla stability variance revealed the same grouping of genotypes، and introduced Boyer cultivars and line No. 28 as the most stable genotypes. It was not possible to distinguish high yielding and stable genotype based on environmental variance. Based on the results obtained، 90. 87% of interaction sum of square was composed of change in rank sum of square and sum of square due to incomplete correlation between genotype ranking in environments which represents the two first types of Lin and Binns stability concepts. Boyer cultivar was the most stable and high yielding genotype. The method of partitioning the genotype  environment interaction to change in rank and Chang in value was found to be the most efficient one amongst the univariate methods for detecting stability.