Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Committee Chair(s)

Bruce Bugbee


Bruce Bugbee


Jennifer Boldt


Youping Sun


Silicon (Si) is not considered an essential element for plants to complete their lifecycle, but is known to be beneficial for plants under environmental stress such as drought. Unlike natural soils, Si is minimally bioavailable in soilless media. With indoor agriculture and greenhouse production increasing, the benefits of Si have been seen and Si should be supplemented. This work aimed to characterize and quantify the dissolution of Si from media substrates and additives to achieve a steady-state release of Si in soilless media. Typical media components such as coconut coir, peat moss, perlite, rock wool, sand, and vermiculite minimally released Si and depleted within 60 days. Wollastonite, a calcium silicate mineral, and rice hulls steadily released Si in water. The dissolution of wollastonite rapidly released bioavailable Si in peat-based media, but decreased over 120 days while rice hulls gradually released. Both amendments increased coconut coir and peat-based media pH. Either would provide bioavailable Si over the lifecycle of many crop species. To test the dissolution of Si, wollastonite was used to amend peat-based media to grow Cannabis sativa L. under precision drought stress. Precision drought stress can be a useful method for growers to maintain plant size and photosynthetic rates, but it is a sensitive system to balance. We hypothesized that Si would increase the resiliency of Cannabis in this system under drought stress. Although Si supplementation did not increase tolerance of Cannabis to drought stress, Si supplementation inhibited powdery mildew (Golovinomyces sp.), a common fungal disease in outdoor and indoor production, in all three trials compared to Si non-supplemented treatments. Silicon is a beneficial nutrient for crops that should be supplemented in soilless media to increase tolerance to environmental stress such as drought stress and biotic stress such as fungal disease, but requires further study.