Muhammad Nauman* Department of Plant Breeding and Genetics, Faculty of Plant Production Sciences, The University of Agriculture, Peshawar, 25130, Pakistan *Corresponding author’s email: nauman_279@yahoo.com Received: 17 January 2026 / Revised: 14 March 2026 / Accepted: 26 March 2026 / Published Online: 04 April 2026 Abstract Brassica juncea is one of the major oilseed crops in the subcontinent and worldwide, with its performance affected by environmental conditions; therefore, understanding the genotype × environment interaction (GEI) is essential for identifying high-yielding and stable genotypes. Forty-five B. juncea genotypes were evaluated across four diverse locations in Khyber Pakhtunkhwa over two years to assess stability and high yield. For this purpose, additive main effects and multiplicative interaction (AMMI) analysis was applied to seed yield and oil content, following a significant GEI. Significant (P≤0.01) GEI was observed for the studied traits, indicating substantial differences among genotypes across tested environments. Overall, higher seed yield was recorded for genotypes AUP-619 and AUP-641, and elevated oil content was found for AUP-1800, as compared to the check cultivars. The AMMI-1 biplot analysis identified relatively stable and high-yielding genotypes for seed yield and oil content. The biplot also revealed that the Kohat and Bannu environments showed limited discriminatory ability for both traits among genotypes, likely due to uniform environmental stress and restricted genetic variation for both traits. Additionally, the AMMI-2 biplot assessment detected two possible mega-environments for seed yield and oil content, along with their associated genotypes, highlighting the significance of environment-specific allocation of genotypes. Moreover, the genotype selection index identified comparatively stable and high-yielding genotypes, such as AUP-618 for seed yield and AUP-625 for oil content. These findings demonstrate the effectiveness of AMMI-based approaches in identifying relatively stable and specifically adapted B. juncea genotypes for diverse agro-climatic conditions. Keywords: Genotype × Environment interaction (GEI), Stability analysis, AMMI analysis, AMMI stability value (ASV), Genotype selection index (GSI) | 
