Foliar application of 2-amino-3-methylhexanoic acid enhances low temperature tolerance in five key horticultural crops

Low temperature (LT) stress is a major factor limiting crop productivity in temperate and subtropical regions. 2-Amino-3-methylhexanoic acid (AMHA), a novel natural plant resistance inducer (PRI), demonstrates significant potential for mitigating LT-induced physiological damage. This study assessed the efficacy of AMHA in enhancing cold tolerance across five key horticultural crops―pepper, tomato, strawberry, cabbage, and tea―under field conditions. Comparative trials with conventional PRIs, brassinosteroid (BR) and alginate oligosaccharides (AOS) revealed that AMHA, even at low doses (8.7−65.3 mg ha−1), significantly enhanced seedling vigor by stimulating root and shoot growth. This improvement not only increased LT tolerance but also promoted vegetative growth, reproductive potential, and ultimately overall yield and fruit quality. Notably, AMHA consistently exceeded BR and AOS in promoting cold tolerance, exhibiting high efficacy across these taxonomically diverse crops. Toxicological evaluations confirmed its excellent safety profile, with minimal non-target toxicity and no observable irritation or sensitization in animal models, and non-mutagenic properties. These findings highlight AMHA as a promising PRI with broad-spectrum efficacy, rapid action, high potency, and environmental compatibility.