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SELECTION OF STABLE RAPESEED (BRASSICA NAPUS L.) GENOTYPES THROUGH REGRESSION ANALYSIS

NAAZAR ALI, FARZAD JAVIDFAR* AND M. Y. MIRZA

Abstract: Twenty-five elite genotypes of winter rapeseed were evaluated through regression analysis for their phenotypic stability in seven cold and six mild cold regions of Iran. Sufficient GE interaction was exhibited by the genotypes for seed yield which is pre-requisite to regression and stability analysis Across the 13 environments, Alice and Olera genotypes were at par and produced 3.40 t/ha. Thirteen genotypes showed above average mean performance. Erumia (cold) and Islamabad (mild cold) regions with yield of 4.35 t/ha were found suitable for this germplasm. Both linear as well non-linear components of GE interaction were significant and reflected the differential response of the tested genotypes to different environmental changes. Regression coefficients ranged from 0.29 to 1.35 in Syn-1 and DP-94-8 respectively. Four genotypes (Symbol, Fornax, Parade and Okapi) had b-values close to unity with average performance and low deviation from regression (S2d), and were suitable for wider range of environments. Orient, Cocktail, Alice, Olera, Reg x Cob and SML-046 were found suitable for favourable environments due to their regression coefficients greater than unity, above average performance and low S²d. Due to below average response (b<1) and least S²d, Eurol, Hansen, Colvert, Mohican, Orkan and VDH-8003 were suitable for poor environments. The performance of GWC, Licord and Consul was unpredictable because of their significant S²d.
 

Oilseed Research Program, National Agricultural Research Centre, Islamabad, Pakistan.
Oilseed Research Departmenrt, Seed and Plant Improvement Institute, Karaj, Iran.