Brassica juncea L. is one of the major oilseed crops in Pakistan and globally, with productivity sensitive to environmental variation. Forty-five B. juncea genotypes, evaluated across four locations over two years in Khyber Pakhtunkhwa, Pakistan, used a randomized complete block design with two replications. Significant (p ≤ 0.01) genotype and genotype × environment interaction (GEI) differences for seed yield and oil content led to genotype plus genotype × environment (GGE) biplot analysis to identify high-performing and stable genotypes across test environments. The GGE biplot view for mean vs. stability identified AUP-618, AUP-619, and AUP-623 for seed yield and AUP-625, AUP-626, and AUP-653 for oil content as high-yielding and stable genotypes. The polygon view revealed two mega-environments per trait, indicating crossover GEI. For seed yield, Peshawar and Mardan (2017-18) formed one possible mega-environment with AUP-600 and AUP-619 as winning genotypes, while Kohat (2016–17) and Bannu (2017–18) constituted the second with AUP-645. For oil content, Peshawar and Bannu comprised one potential mega-environment with AUP-645, whereas Mardan created the second with AUP-632. Furthermore, Mardan (2016–17) for seed yield and Peshawar (2017–18) for oil content emerged as the tentative ideal environments. GGE biplot analysis effectively identified high-yielding and relatively stable B. juncea genotypes for diverse Khyber Pakhtunkhwa environments.
B. juncea, genotype-by-environment interaction (GEI), stability analysis, GGE biplot, seed yield, oil content
The B. juncea genotypes AUP-618, AUP-619, and AUP-623 for seed yield and AUP-625, AUP-626, and AUP-653 for oil content succeeded in their identification as high-yielding and relatively stable genotypes. Two possible mega-environments, detected for both traits, indicated crossover GEI, with Mardan (2016–17) and Peshawar (2017–18) identified as the ideal environments for seed yield and oil content, respectively.