| Abstract: In order to explore the effects of exogenous selenium and fulvic acid potassium (FAK) on soil and onions cultivation in selenium-deficient areas, the effects of FAK combined with different concentrations of selenium (Se, 0.1%, 0.2%, 0.3%) on the translocation characteristics, yield and the influence of agronomic traits were studied by taking potted cultivation methods, using the black soil lacking selenium in the northeast as the test soil. The results showed that the content of Se in each part of onion increased with the amounts of application of sodium selenite. Compared with the optimized formula treatment, FAK application could increase the enrichment coefficient to Se of onion and increase the translocation coefficient from root to bulb. The selenium content in onion increased significantly with the increase of selenium concentration, the transfer coefficient from root to bulb was the largest, and the translocation coefficient from bulb to pseudostem and pseudostem to tubular leaf was the lowest when FAK and 0.1% sodium selenite was applied in combination. Treatment of FAK with optimized formula could increase the yield of onion. When FAK was combined with 0.1% sodium selenite, yield of onion was significantly higher than other treatments, and the plant height, pseudostem diameter, number of leaves and content of chlorophyll of onion were also better than other treatments. Under the pots experimental conditions, fertilization treatment of the "optimized formula+0.5% FAK+0.1% Se" had a good promotion effect on Se enrichment, the yield and agronomic traits of onion in selenium-deficient soil, which was the best fertilization formula. |