In my experiment, silicates, salts that contain silicon and oxygen, are used to potentially increase the drought tolerance of romaine lettuce and perennial ryegrass. Silicon has many known benefits in the growth of plants, such as enhanced uptake of major essential nutrients, like nitrogen, phosphorous, and potassium (Eneji, A. Egrinya, et al., 2008) and the ability to increase cell wall strength, disease and insect resistance, upright growth and rigidity, shoot and root density, yields (Scarbrough, 2007).

For each study, five groups of each plant were grown under simulated drought conditions (20% of water holding capacity) and five groups were grown under adequate watering conditions (60% of water holding capacity, with 5 replicates per group. I applied 200 mg/L, 400 mg/L, and 800 mg/L sodium metasilicate in drought and sufficient (control) watering. Two groups involved seeds that were primed with 800 mg/L sodium metasilicate in drought and adequate watering conditions. My controls were plants grown without any silicate applications in both watering conditions. Silicon uptake was estimated colorimetrically using the Autoclave Induced Digestion (AID) method (Elliot and Snyder, 1991). I hypothesized that as the amount of silicon solutions additions to Lactuca sativa and Lolium perenne in water deficit conditions increases, the plants' drought tolerances as well as silicon uptake will increase, as evaluated by the lettuce's biomass and the grass's biomass, dry weight, and height.

All statistical analysis was performed with unpaired t-tests and ANOVA with post-hoc Tukey HSD tests. In my lettuce study, groups that were treated with 400 mg/L and 800 mg/L sodium metasilicate in sufficient watering levels showed a statistically significant increase in biomass when compared to the control. In drought conditions, romaine lettuce grown with 400 mg/L silicate applications displayed the best growth, exhibiting a statistically significant increase. Primed groups as well as those watered with 800 mg/L sodium metasilicate showed statistically significant increases in comparison to the control. In my perennial ryegrass study, plants grown under drought stress generally had higher yields than those grown with sufficient water under the same sodium metasilicate treatment across all assays, with the exception of the seed primed groups. The group treated with 800 mg/L sodium metasilicate under drought conditions showed the highest biomass yield, height, and dry weight by statistically significant means. The methods of determining silicon concentration in plants was highly limited at the high school setting. The estimated silicon uptake did not correlate completely with results displayed by the other data assays: biomass, height and DW. However, all groups treated with sodium metasilicate displayed an uptake of silicon into their plant tissue; the groups whose seeds were primed before planting had the highest estimated silicon concentration.

The concentration of silicate needed to produce the best results may depend on the plant species, as I observed that the lettuce plants grew best with 400 mg/L and the grass grew best with 800 mg/L of sodium metasilicate, contrary to my hypothesis. Seed priming suggests to be a very cost-effective and efficient way to implement silicon into plants as silicates introduced in the seed stage are present still when the plants are mature. In an agricultural aspect, adding silicates to irrigation systems in agricultural fields, drought or not, is a cost-effective way to improve biomass yields of produce with the same amount of water used. In terms of landscape irrigation, silicate applications even at small concentrations do increase the drought tolerance of grass and would be extremely beneficial in reducing water used for landscaping while increasing cost-effectiveness.