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[Display omitted] • Garlic Se absorption and transportation were largely affected by Se speciation. • Organic Se was superior to inorganic Se in enriching Se and antagonizing Cd. • Bulb Se content treated with organic Se was about twice (or more) than inorganic Se. • Organic Se was significantly more effective in reducing Cd content than inorganic Se. • Se was mainly enriched in bulb, Cd was enriched in root under organic Se application. Currently, planting selenium-rich crops using inorganic selenium such as selenate and selenite is used to address human selenium deficiency problems. In this paper, besides the above two traditional inorganic selenium speciation, we chose a new organic selenium speciation of potassium selenocyanoacetate to investigate the different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism via foliar application. Planting experiments showed that the selenium content of garlic bulbs treated with organic selenium was 1.8–3.9 times higher than that of inorganic selenium. Additionally, the absorption and transformation efficiency of organic selenium in garlic was also the highest, reaching over 95 %. Importantly, it was noteworthy that the cadmium content in bulbs treated with organic selenium was significantly lower than the Chinese food safety standard (0.2 mg/kg). Hence, this study provides an efficient organic selenium speciation which is beneficial to meet human selenium requirements and ensure safe utilization of cadmium-contaminated soils. [ABSTRACT FROM AUTHOR]