LAUSR

Abstract Cadmium (Cd) stress restricts maize growth and productivity severely. We aimed to investigate the effects of Hemin on the metabolism of sucrose and nitrogen and endogenous hormones in maize under cadmium stress. Maize varieties ‘Tiannong 9’ (cadmium tolerant) and ‘Fenghe 6’ (cadmium sensitive) were grown in nutrient solutions to study the effects of Hemin on maize physiological and ecological mechanisms under cadmium stress. The results showed that Hemin mediated the increase of sucrose content and the activities of key enzymes sucrose phosphate synthase (SPS) and sucrose synthase (SS) in maize leaves under cadmium stress. Soluble acid invertase (SAInv) and basic/neutral invertase (A/N-Inv) enzyme activities in leaves were decreased significantly, and sucrose accumulation in leaves was increased. Hemin also mediated the increase of NO3 − content in leaves, the decrease of NH4 + content and the increase of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase activity (GOGAT) and glutamate dehydrogenase (GDH) enzyme activities under cadmium stress. The contents of IAA, ZR, and GA in leaves and roots increased, ABA, MeJA, and SA decreased, and IAA/ABA, ZR/ABA, and GA/ABA increased under cadmium stress. Our study showed Hemin can alleviate cadmium stress in maize by enhancing sucrose and nitrogen metabolism and regulating endogenous hormones. NOVELTY STATEMENT This work further investigates the effects of Hemin on the metabolism of sucrose and nitrogen and endogenous hormones in maize under cadmium stress, which, hopefully, is to guide Hemin application to maize field resilience production. It also explains that Hemin is beneficial for dry matter accumulation and transport, alleviated ammonia toxicity and nitrogen metabolism disorder, and induced the changes of endogenous hormone content and the adaptive hormone ratio balance under cadmium stress.