Phenotypic evaluation and plasticity analysis of drought resistance in 201 maize inbred lines

Drought is the primary constraint limiting maize yield improvement. Phenotypic plasticity describes how a given genotype responds to environmental variation; therefore, evaluating drought plasticity in maize inbred lines is essential. Using drought-resistance-related data for 201 inbred lines evaluated across five environments and two water regimes during 2019-2020, we assessed drought resistance using three approaches, including factor analysis, and classified the lines into four levels: highly resistant (HR), resistant (R), moderately resistant (MR), and weakly resistant (WR). Lines such as KA105, KB020, and Zong 31 showed strong drought resistance. Plasticity was then quantified using the Finlay-Wilkinson (FW) regression, and two drought plasticity patterns were defined: G×E positive plasticity (a genotype shows a significantly better positive response than its overall mean performance in specific environments) and no G×E positive plasticity (a genotype performs stably across environments and does not show a significantly better positive response relative to its overall mean in any environment). KA105 and M1801 were classified as the G×E positive plasticity type, whereas 09B-6-2 was classified as the no G×E positive plasticity type. Overall, KA105 combined strong drought resistance with G×E positive plasticity, indicating that it is a promising germplasm source for drought-resistance breeding with potential for broad application.