Evaluating phenotypic plasticity of reproductive traits among Korean rice cultivars under diverse climatic conditions

Developing climate-resilient cultivars is crucial for maintaining global rice production amid increasing climatic uncertainty. Harnessing phenotypic plasticity provides a promising pathway to enhance crop adaptability; however, a comprehensive understanding of how environmental factors shape phenotypic responses remains limited. In this study, we rigorously assessed the phenotypic plasticity of key reproductive traits in 100 Korean rice cultivars representing three distinct maturity groups. We constructed a comprehensive dataset by combining measurements from a precision-controlled plant phenotypic-measuring automated greenhouse (PMAG) with two field environments with contrasting climatic conditions: a dry year (2018) and a wet year (2020). Using Z-score standardization and kernel density estimation (KDE), we analyzed trait distributions and their environmental shifts to reveal plasticity patterns across conditions. Panicle length and total seed number exhibited pronounced variability, with medium-late-maturing cultivars generally showing higher mean and median values, suggesting greater potential for enhanced panicle development and yield. Specifically, the mean panicle length increased from a minimum of 17.99 cm in the early-maturing group under 2018 field conditions to a maximum of 22.10 cm in the medium-late group under the 2023 PMAG environment. The number of seeds per panicle also showed an upward trend, reflecting improved reproductive output under the controlled PMAG conditions. Overall, climatic variability, particularly rainfall patterns and controlled environment factors, strongly influenced the manifestation of reproductive traits. This environmental influence was clear in the significant shifts in trait expression observed across the three maturity groups. These results establish a robust multi-environment analytical framework that disentangles environmental-phenotypic relationships in rice. Climatic factors were shown to differentially regulate reproductive development through maturity-dependent plasticity. Early-maturing genotypes exhibited higher environmental sensitivity, whereas medium- and late-maturing groups displayed greater buffering capacity. This provides a predictive basis and a practical breeding strategy for developing climate-resilient rice cultivars suited to future agroecosystems.