Systemic decoupling of trait coordination: network-based identification of multi-stress resilient maize ideotypes

Area of Science:

• Agricultural Science
• Plant Physiology
• Genetics

Background:

• Maize (Zea mays L.) productivity is threatened by environmental stressors like drought and low nitrogen.
• Understanding maize's response to these stresses is crucial for ensuring global food security.

Purpose of the Study:

• To evaluate the impact of drought and low nitrogen stress on maize morphological traits and yield.
• To identify key traits and genetic factors contributing to yield stability under stress.
• To identify resilient maize varieties for cultivation in resource-limited environments.

Main Methods:

• Morphological data collection from 21 maize varieties under controlled drought and low nitrogen conditions.
• Analysis of vegetative and reproductive traits, including the Anthesis-Silking Interval (ASI).
• Network analysis to understand trait interdependencies under different stress conditions.
• Calculation of the Stress Tolerance Index (STI) to identify resilient varieties.

Main Results:

• Drought significantly increased the Anthesis-Silking Interval (ASI) by ~4-fold, reducing grain yield per plant (GYP) by 27% and decoupling traits.
• Under drought, tip blanking and empty kernel rate became key negative regulators of yield.
• Maize exhibited resilience to low nitrogen, with GYP unaffected due to increased total kernels per ear, a sink-protected compensation strategy.
• Kernel length and hundred-kernel weight decreased under low nitrogen, but yield was buffered.

Conclusions:

• Reproductive synchrony, particularly the Anthesis-Silking Interval (ASI), is critical for maize yield stability under drought.
• Maize employs effective compensatory mechanisms to maintain grain yield per plant (GYP) under low nitrogen conditions.
• Xinyu 108, Ruipu 909, and Weike 702 demonstrated multi-stress resilience, offering potential for breeding programs targeting resource-limited environments.