Dynamic characteristics of leaf intracellular water, nutrients, metabolic energy, and photosynthetic responses to drought stress in maize

Drought stress poses a major challenge to global agriculture, significantly impacting crop growth, photosynthesis, and metabolic processes.This study introduces an innovative electrophysiological approach to assess 'Xinnuo 628' sweet glutinous maize (Zea mays L. var.ceratina) responses to drought stress by integrating intracellular water, nutrient transport, and energy dynamics.The experiment was conducted in a controlled greenhouse environment with three water regimes: Control (CK, 75% field capacity), moderate drought (T1, 55%), and severe drought (T2, 35%) over 18 d.The results highlight a critical physiological inflection point on day 9 in T1, suggesting that timely irrigation at this stage could prevent irreversible damage.Under severe drought (T2), the net photosynthetic rate (PN) dropped to 3.8 0.9 molms, and stomatal conductance (gs) decreased to 0.09 0.02 mmolms.In contrast, T1 plants maintained a higher leaf intracellular waterholding capacity (LIWHC: 2701.34 122.69) and metabolic energy reserves (GB: 356.73 40.28 at day 18), enabling prolonged physiological activity despite water limitations.Electrophysiological parameters proved to be more sensitive and representative than traditional photosynthetic indicators.While LIWHC and intracellular water-use efficiency declined more gradually in T1 than in T2, photosynthetic parameters fluctuated inconsistently, especially in T2, where PN unexpectedly increased on day 18.These findings demonstrate that electrophysiology provides a real-time, non-invasive tool to detect early stress signals and enable precise irrigation adjustments before irreversible damage occurs.By identifying the critical transition phase in T1, this study lays the basis for optimizing water use efficiency and improving maize resilience under drought conditions, contributing to the advancement of precision agriculture.