Selenium stimulates soybean sprout growth, research indicates

Moderate concentrations of sodium selenite stimulated the growth of soybean sprouts and increased the antioxidant capacity of the plants. The best performance occurred with 5,0 and 7,5 micromol/L of Na2SeO3, after 72 hours of dark cultivation. At these doses, the sprouts showed greater hypocotyl elongation, greater biomass accumulation, and better mobilization of cotyledon reserves. This information comes from a study by Chinese researchers.

The study evaluated the Bayan cultivar under five selenite concentrations: 0, 2,5, 5,0, 7,5, and 10 micromol/L. Germinated seeds were kept in culture boxes at 30°C in the dark. The solutions were changed every 24 hours. At the end of the period, researchers measured length, fresh mass, selenium content, and physiological indicators in the radicle, hypocotyl, and cotyledon.

The concentration of 7,5 micromol/L generated the greatest growth gains. The radicle grew 26,0% compared to the control. The fresh mass of the radicle increased by 40,7%. The hypocotyl showed a 19,0% increase in length and fresh mass. The dose of 5,0 micromol/L also promoted relevant gains, with a 19,6% increase in radicle length and a 10,2% increase in hypocotyl length.

Distinct accumulation

Selenium accumulated differently in the tissues. The highest concentration occurred in the radicle, followed by the hypocotyl. The cotyledon showed the lowest values. This pattern indicates absorption by the radicle and limited translocation during germination in the dark.

Moderate doses also activated the antioxidant system. At 5,0 and 7,5 micromol/L, there was an increase in the activities of superoxide dismutase, peroxidase, and ascorbate peroxidase. These enzymes act in the removal of reactive oxygen species. The treatment also elevated reduced glutathione, ascorbic acid, and free proline in different tissues.

This response reduced oxidative stress. Superoxide anion and hydrogen peroxide concentrations decreased in moderate treatments. Malondialdehyde, an indicator of lipid peroxidation, also decreased. At a dose of 7,5 micromol/L, MDA decreased by 20,9% in the radicle, 22,7% in the hypocotyl, and 31,8% in the cotyledon.

Mobilization of reserves

The study also showed an effect on the mobilization of reserves. Selenite increased the activity of amylases and proteases in the cotyledons. α-amylase increased by 106,4% at 7,5 micromol/L. Alpha + berta-amylase activity rose by 64,8% at the same dose. Protease increased by approximately 50% at 5,0 and 7,5 micromol/L.

This process favored the conversion of reserves into soluble sugars, soluble proteins, and free amino acids, the researchers point out. In the hypocotyl, the content of soluble sugars increased by 36,8% with 5,0 micromol/L and by 65,4% with 7,5 micromol/L. Free amino acids increased 4,50 times with 5,0 micromol/L and 4,43 times with 7,5 micromol/L. These compounds supported elongation and mass gain.

The 10 micromol/L dose had the opposite effect. The treatment suppressed antioxidant activity, elevated reactive oxygen species, and increased MDA. Growth lost the stimulus observed at moderate doses. The authors relate this effect to excess selenium, which can disrupt redox balance and impair the mobilization of reserves.

The results indicate potential for biofortification of soybean sprouts with selenium. According to the researchers, the application of selenite between 5,0 and 7,5 micromol/L strengthened antioxidant defense, reduced oxidative damage, and favored the transport of reserves to the hypocotyl. The work points to a physiological basis for protocols for the production of sprouts enriched with selenium.

Further information can be found at doi.org/10.17221/72/2026-PSE