Studies on Gracilaria salicornia: Zinc Oxide (ZnO) Sunscreen Exposure and Use as Agricultural Fertilizer

Overview

Limu (seaweed) is critical to Native Hawaiian ecosystems and culture. With limited prior research, the first part of this study examined the effects of ZnO mineral sunscreens on endemic Hawaiian Gracilaria coronopifolia (Limu Manauea) and invasive Gracilaria salicornia (Gorilla Ogo). For three months, samples were measured twice weekly for length and apical tip counts. ZnO had a more negative effect on the percent change in length and apical tip count of the endemic G. coronopifolia than the invasive G. salicornia. Due to the invasive G. salicornia being so abundant in Hawaiian ecosystems, for the second part of the study, four fertilizers were developed: two created from fermented G. salicornia: 10% and 25% concentrations, two from desiccated G. salicornia:1.0% and 2.5% concentrations. Corn, green bean, and romaine lettuce seeds were treated and observed (number germinated and radicle length of germinated seeds). The 10% liquid fertilizer was found to significantly increase the radicle length of all tested seeds, while the 2.5% dry fertilizer had detrimental effects. In the final experiment, where broccoli plants were used rather than plant seeds, two additional fertilizers (1.0% GF and 2.0% GF) were composed of desiccated G. salicornia as an improvement to the dry fertilizers. The 10% liquid fertilizer again increased growth of the broccoli plants when compared to the control. Future research is necessary to determine the biochemical basis for the contrast in outcomes between the liquid vs. dried/gel fertilizers, which could provide new insights into fertilizer development.

Competition history

JSHS 2023 Category not listed

Resources

National JSHS abstract book

Related projects

ISEF · 2023