Dual effects of slightly acidic electrolyzed water on rice seed germination: insights from water dynamics via low-field NMR

To investigate the effects of slightly acidic electrolyzed water (SAEW) treatment on rice seed germination, rice seeds were soaked with SAEW at different available chlorine concentrations (ACC) of 10, 20, 30, 40, 50, and 60 mg/L. A standard seed germination test was conducted to summarize the influence of SAEW with varying ACC on rice seed germination. Meanwhile, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) technologies were employed to reveal the underlying mechanisms by studying the internal moisture changes, water migration patterns, and water distribution characteristics. The results demonstrated a hormetic effect of SAEW on rice seed germination, characterized by significant promotion at lower ACCs (10–40 mg/L) and inhibition at higher ACCs (50–60 mg/L). The most pronounced promotive effect was observed at an ACC of 30 mg/L. Low ACC SAEW accelerated the water storage rate within the rice seeds, facilitated the conversion and accumulation of free water, thereby providing favorable moisture conditions for seed germination and subsequently promoting rice growth. In contrast, high ACC SAEW damaged the rice cell walls under osmotic stress, leading to a reduced water absorption rate and consequently inhibiting rice growth. This study, starting from the pre-treatment of rice seeds, investigated the entire process, providing theoretical support and data reference for rice production and processing.