Systemic decoupling of trait coordination: network-based identification of multi-stress resilient maize ideotypes
The agricultural sector faces significant challenges in maintaining crop productivity under environmental stressors such as drought and low nitrogen (LN) availability. Maize (Zea mays L.), a globally important cereal crop, is particularly vulnerable to these adverse conditions. We evaluated morphological data of 21 maize varieties under drought and low nitrogen. Results showed that vegetative traits showed moderate plasticity, while reproductive synchrony was the primary driver of yield stability. Drought stress led to a ~4-fold expansion of the Anthesis-Silking Interval (ASI), increasing from 0.14 to 0.55 days, which contributed to a 27% reduction in grain yield per plant (GYP). The network analysis showed that under drought, traits became fundamentally decoupled. In well-watered conditions, growth and yield formed a highly coordinated hub, but under water deficit the network fragmented — with tip blanking (r = –0.44) and empty kernel rate (r = –0.37) emerging as the key negative regulators. Conversely, the germplasm showed resilience to low nitrogen, with grain yield per plant (GYP) showing no significant difference from control (215 ± 19.3 g vs. 218 ± 21.5 g; P > 0.05). Under low nitrogen, kernel length (−2.1%, P < 0.05) and hundred-kernel weight (−3.2%, P < 0.05) decreased significantly, but total kernels per ear increased by 7.1% (P < 0.05), fully buffering yield through a sink-protected compensation strategy. Utilizing the Stress Tolerance Index (STI), we identified Xinyu 108, Ruipu 909, and Weike 702 as elite, multi-stress resilient varieties, highlighting their potential for cultivation in resource-limited environments. This research offers valuable insights for breeding programs focused on developing resilient maize varieties.