Yield Stability Assessment of Winter Oilseed Rape Lines in Cold Regions of Iran Using AMMI Model

Rapeseed (Brassica napus L.; AACC, 2n = 38) is the most important edible oilseed crop in the world . In most breeding programs specially when comparing several varieties in different environments, because of line×environment interaction, lines in different environments show variable performances. For this reason, it is difficult to recommend and introduce superior cultivars in vast environments. Genotype×environment interaction can be estimated using diffrerent statistical procedures.This study was performed for determination of yield stability for 25 winter lines. Breeding to increase yield per surface unit is associated with the production of varieties that are able to properly utilize environmental conditions. therefore it is necessary to review and evaluate the compatibility of different cultivars in the target environments.

This study was conducted to evaluate compatibility and yield comparisons in cold and temperate cold conditions of the country. In which 20 winter rapeseed lines with two promising lines and three cultivars namely Okapi, Ahmadi and Modena in a Randomized Complete Block Design (RCBD) with three replications were planted and compared. This experiment conducted in five place (Karaj, Hamedan, Kermanshah, Tabriz and Arak) during two years of cultivation (2009-10, 2010-11). In this experiment, the AMMI (additive main effects and multiplicative interaction) method was used to investigate the effects of multiplicity (genotype × environment interaction) and reaction analysis of the lines studied. In this research, SAS (Statistical Analysis System) software was used for analyzing AMMI method and Sigmaplot software was used for drawing plots.

Simple effects of location, genotype and genotype×environment interaction were significant. Analysis of AMMI method showed environmental portion of line×environment interaction had highest effect in seed yield. Based on this analysis, the first three principle components were significant at 1% probability level and the fourth principle component was significant at 5% probability levels and accounted for 26.8%, 21.23%, 13.58% and 10.99% of interaction sum of squares respectively. HW112 and L120 lines showed lower ASV after SW101, but the L120 line was found to have lower yields than the total average as high yield stable lines.

Sustainability evaluation using ASV index showed that SW101 line has the highest stability. This line was considered as a genotype with good general stability by having the lowest ASV and higher performance than the total average. Finally, SW101was introduced as a genotype with good general stability due to the lowest interaction effect and the mean yield higher than the mean average.