Elevated Silicon Ameloriates Drought Stress.

Here we report the effect of supplemental silicic acid on the drought tolerance of four crop plants (corn, wheat, soybean, and rice).  In one series of studies, plants were cultivated in hydroponic solution and subjected to salt stress.  In a second series of studies, plants were grown in 16 weighing lysimeters in a greenhouse and subjected to both acute and chronic drought stress.  Supplemental silicon increased corn dry mass by up to 20% (p<0.05) in three out of ten trials, and increased water use efficiency by up to 36% (p<0.05) in one out of four trials.  In contrast to some other studies, the effect of silicon on the uptake of other nutrients was not physiologically significant.  Silicon in plant leaves increased from zero to 5% as Si increased from zero to 0.8 mM in the root-zone solution. Collectively, these results indicate an effect of silicon in drought and salinity stress tolerance, but additional studies are needed to determine interacting factors and better understand the inconsistent results.