Effect of Si on the distribution of Na (salt) in Barley

California State University, Fresno

This laboratory investigation with barley was conducted to determine the mechanism of salt toxicity. For the determination of monosilicic, polysilicic acids and Na in apoplast and symplast of roots, stems and leaves, we used a specifically elaborated methodology. The obtained result has shown that there are several mechanisms available to strengthen plants against Na toxicity through improving Si plant nutrition. Soluble Si compounds can block or delay Na transport in apoplast. Monosilicic acid protects chlorophyll molecules against the effect of Na demolition. Soluble Si reduces the active transport of Na into root apoplast. The cells in symplast of barley roots and stems have strong mechanisms for blocking of Na thus preventing sodium toxicity. On the other hand the optimization of Si plant nutrition can also initiate additional penetration of Na into root symplast. The obtained data also demonstrated that the  main reserve of active Si, is locates in barleys leaves. When plants feel stress, this Si- reserve can be rapidly transported to problematic areas. This new methodology gives us the possibility to direct our investigation of plant physiological processes to a new level of knowledge.