Silicon addition to soybean (Glycine max L.) plants alleviate zinc deficiency

• Silicon effect in zinc deficiency symptoms alleviation and Zn distribution in soybean plants has been studied.
• Initial or continuous Si supplies (0.5 or 1.0 mM) at the nutrient solution were tested.
• Si 0.5 mM initial application increased Zn content in root apoplast, which will be remove to leaves at Zn deficiency.
• A continuous or a greater supply (1.0 mM) of Si would not be more beneficial.

It is well established the beneficial role of silicon (Si) in alleviating abiotic stress. However, it remains poorly understood the mechanisms of the Si-mediated protection against metal deficiency, especially the zinc (Zn) one. Recently, it has been proposed that Si may act by an interaction with this biometal in the root apoplast contributing to its movement through the plant, as in the case of Fe deficiency. In the present work, the effect of initial or continuous Si doses in soybean Zn deficient plants has been studied. For that purpose, plants grown in hydroponic culture were treated with different Si doses (0.0, 0.5 and 1.0 mM) under Zn limiting conditions. SPAD index in leaves, several growth parameters, mineral content in the whole plant and the formation of Zn pools in roots were determined. An initial addition of 0.5 mM of Si to the nutrient solution led to an enhancement of plants growth, Zn and Si content in leaves, and a higher storage of Zn in the root apoplast. The results suggest that this treatment enhanced Zn accumulation on roots and its movement to shoots when needed, mitigating Zn deficiency symptoms.