Genotype × environment interactions and genetic variation reveal stable, high-yielding, and organosulfur-rich garlic cultivars adapted to tropical conditions

Garlic is valued for its yield and sulfur-containing bioactive compounds, but the influence of genotype × environment (G × E) interactions on these traits remains poorly understood. This study evaluated seven garlic cultivars: Tawangmangu Baru (TB), Lumbu Kuning (LK), Sangga Sembalun (SS), Lumbu Putih (LP), Geol (G), Kusuma (K), and Lumbu Hijau (LH), across two agroclimatic regions in Mojokerto (cool) and Pasuruan (warm), Indonesia, during the 2022 and 2023 growing seasons. Key traits, including yield and organosulfur compounds (allicin, S-allyl cysteine [SAC], γ-glutamyl-S-allyl-L-cysteine [GSAC], alliin) were assessed. G × E interactions were analyzed using the Additive Main Effects and Multiplicative Interaction (AMMI) model. Single-nucleotide polymorphism (SNP) variation in the DELLA-like gene Asa4G02090.1 was also examined. Results revealed significant G × E effects on yield and compound synthesis, with TB best performed in cooler environments, whereas LP exhibited stable production across the studied environments. Genetic variation in DELLA-like gene Asa4G02090.1 was highest in high-yielding TB and LK (42.3%) and lowest in LP (26.9%), which corresponds with its phenotypic stability. This study emphasizes the significance of G × E interactions and genetic diversity in selecting high-quality cultivars, offering new insights for breeding programs to develop high-yielding, stable cultivars, particularly in tropical regions.