Abstract
Background: Intensive rice monoculture in Indonesia drives yield stagnation and progressive land degradation. This study evaluated newly developed breeding lines across contrasting crop rotation sequences to identify synergistic genotype-environment combinations that mitigate monoculture-induced degradation. Methods: The experiment was conducted at the Agrotechnology Innovation Center, Universitas Gadjah Mada, Yogyakarta, Indonesia. A factorial Randomized Complete Block Design (RCBD) evaluated two factors: 12 rice genotypes (10 promising breeding lines and two commercial controls) and three rotation environments, namely rice-rice-rice (R-R-R), maize-maize-rice (M-M-R) and vegetable-vegetable-rice (V-V-R). Result: ANOVA showed significant G x E interactions for grain number per panicle (p = 0.0038), harvest index (p less than 0.0001) and number of productive tillers (p = 0.0229). The M-M-R and V-V-R rotations significantly increased the harvest index to 0.34 and 0.35, respectively, compared with 0.22 under R-R-R monoculture (p less than 0.0001). Genotype GM 8 showed superior performance, achieving a maximum harvest index of 0.51 in V-V-R and 299.33 grains per panicle in M-M-R, whereas Inpari 30 Ciherang Sub 1 recorded the lowest efficiency (harvest index 0.17). Switching to maize- or vegetable-based rotations with suitable genotypes, such as GM 8, is therefore a viable approach to improving yield attributes.