Booth Id:
PLNT058
Category:
Plant Sciences
Year:
2024
Finalist Names:
Walsh, Ella (School: University High School)
Abstract:
The unique carbon fixation and CAM photosynthesis process of Tucson, Arizona’s Opuntia
engelmannii (Texas prickly pear) offers reduction to the ever-rising carbon dioxide atmospheric
levels; however, the variability among prickly pears’ CO2 fixation capabilities remains unknown.
Since the oxalate (C2O42-) reserves in Opuntia engelmannii are directly converted from CO2
extracted from the atmosphere, the goal of this research was to construct a reproducible assay to
quantify the amount of oxalate in prickly pear paddles (cladodes) and by extension quantify the
level of carbon fixation within each cladode. As a result of intense experimentation and
optimization to the overall assay and individual steps within it, an assay with 8 core steps —
including manual extraction of calcium oxalate from cladodes, chemical isolation of oxalic acid,
and an oxalic acid-sodium hydroxide titration — was developed from scratch. The effectiveness
of the assay was confirmed by the results of Sample 2, Sample 1’, and Sample 2’: 0.106%,
0.102%, and 0.132% respectively. Although all 3 samples measured similar percentages, the data
set was too small to draw conclusions about true oxalate variability, so the real significance of
these results were reflected by their completion and dual-equivalence titration curves which
served as a proof of concept. In conclusion, this assay provides a great foundation for future
investigation of a possible correlation between environmental conditions and oxalate
concentrations in texas prickly pear. Certain environmental conditions can then be fostered by
individuals to allow prickly pear to maximize oxalate concentrations and by extension maximize
CO2 fixation.