MULTIVARIATE ANALYSIS FOR ADAPTABILITY AND YIELD STABILITY OF RAPESEED (Brassica napus L.) STRAINS IN DIFFERENT AGRO-CLIMATIC ZONES

Plant breeders always look for high yielding genotypes based on both genotype and G x E (interaction of genotype with environment) for stability and adaptability in diversified environmental conditions. This present study consists of eight Brassica napus L. strains using RCBD design with three replications and conducted at eight locations in Punjab province, Pakistan to determine general and specific adaptability in 2014-2015. Additive main effects and multiplicative interactions (AMMI) study showed that the environments (86.65%) have more influence to treatment sum of squares as compare to the interaction of genotype with environment (9.4%) and genotypes (2.65%) respectively, indicating the presence of adequate genetic variation for useful selection to identify stable genotypes. G x E interaction was further partitioned by principal component analysis (PCA). The first four multiplicative axis terms (IPCA1, IPCA2, IPCA3 and IPCA4) give detailed 54.0%, 28.0%, 9.9% and 5.6% of GEI sum of squares (SS), respectively. The AMMI method was used to recognize suitable genotype / genotypes to specific locations / environments. The results showed that genotypes RBN-08004, RBN-04021 and 11-CBN 006 were more stable with the lowest interaction and have general adaptability with yield near about their mean yield. Genotype RBN-08004 has more than average yield, IPCA value closer to zero (1.8), genotype selection index (GSI) is 4 and least AMMI stability value (ASV) of 3.6 therefore considered the most stable. According to AMMI analysis, KN-253, KN-256 and RBN-08004 (adaptive group 1) exhibited specific adaptability for Bhakar and Khanpur with yield greater than mean and positive interaction. Genotype RBN-04047 (adaptive group 2) which has yield lesser than mean yield and positive interaction showed specific adaptability for Chakwal and Karore. It was observed that stability evaluation through AMMI analysis may be used for selection of genotypes from experiments performed under different environmental conditions.