A Yield Stability Survey in Winter Type Canola Using Univariate Methods and Genotypic Distribution Pattern

To study the grain yield stability of winter type canola cultivars (Brassica napus L.) in multiple environments، 18 winter type canola cultivars were evaluated in a complete randomized block design with four replications. The study was conducted in two years and eight cold and temperate regions of Iran. Simple and combined analysis of variance revealed significant differences among genotypes. Moreover، combined analysis of variance displayed significant differences in genotype × location and location × year interactions. Four first interaction principle components (IPCs) were involved in genotype × environment variation (over 75% of G×E interaction). Mean grain yield comparison of genotypes showed that Ebonite، ARC-5 and Elite were the three high yielding varieties (3436، 3338 and 3244 kg ha-1، respectively); on the other hand Opera، Okapi and Licord produced 2698، 2816 and 2823 kg ha-1 grain yield، respectively and were classified as low ranking genotypes. Bi-plot graph of first principle component against grain yield showed that Geronimo، Modena and Sunday (having the lowest principle component) could be grouped as stable varieties. However، Ebonite and ARC-5 were recognized as the most unstable genotypes. Based on different stability analysis methods used in this study، Geronimo، Sunday and Modena with the best stability indices، and high mean grain yield can be introduced as the most stable varieties. Ebonite was recognised as an appropriate variety for specific regions.