Evaluation of Seed Yield Stability and Compatibility in Some Winter Rapeseed Genotypes

Brassica napus (L.) one of the most important oilseeds in temprate climates. In the most breeding programs, especially when comparing several genotypes in different environments, due to the interaction of genotype×environment, genotypes show different performances in different environments. Therefore, to accurately estimate grain yield, multi-environment tests should be performed by breeders.

In order to study the interaction between genotype × environment and identify stable genotypes, 16 rapeseed genotypes were tested in five regions of Karaj, Kermanshah, Isfahan, Mashhad and Hamedan in a randomized complete block design with three replications for two cropping years (2016-2017 and 2017-2018). In order to analyze the interactions of genotype with the environment, the model of additive main effects and multiplicative interactions (AMMI) and the GGE biplot model (genotype and genotype interaction in the environment) were used. AMMI stability value (ASV) was used to evaluate the stability of genotypes.

The Results of combined analysis of variance showed that 40.59, 26.01 and 33.39 percent of total variation were related to the effect of environment, genotype effect and genotype×environment interaction, respectively. The results showed that the first four main components of AMMI were significant and explained 85.5% of the total sum of squares of genotype×environment interaction. Stability assessment using ASV parameter showed that genotypes No. 7 and 2 had the highest stability, respectively. These genotypes with the lowest ASV rate and higher overall performance were known as genotypes with good general stability. The study of polygonal biplot of GGE recognized four superior genotypes and two mega-environments and the best genotypes within each environment were determined. The other five genotypes were located in sectors that no environment was present and these genotypes were weak in the most environments. Simultaneous study of the stability and yield of genotypes using average environment coordinate biplot showed that genotypes No. 13 and 15 were the most unstable genotype for grain yield. Genotype No. 9 was selected as highest grain yield and relative yield stability. The two genotypes No. 9 and 7 were the closest genotypes to the ideal genotype.

Analysis of AMMI and AMMI stability value (ASV) compared to GGE biplot showed that all of these indices had good potential for evaluating the stability of genotypes, but GGE biplot could be more widely used and more useful and can be applied extensively in the study of yield adaptability and stability of winter rapeseed genotypes in multi-envirnmental trials in breeding programs. Finally, genotypes No. 7 and 2 are recognized as most stable genotypes with the lowest interaction effect and mean yields higher than the mean average.