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Variations of fundamental physical constants have been sought for many years using various astronomical objects because their discovery can be key to developing beyond-standard physics. In particular, nuclear reaction rates are sensitive to fundamental constants, so nucleosynthetic processes can be used as a probe. We calculate the evolution and nucleosynthesis of massive Population III stars with the time-dependent nucleon&ndash, nucleon interaction &delta, NN , which may have left traces in elemental abundances in extremely metal-poor stars. The results are compared with the abundances in the most iron-poor star that has ever been discovered, namely, SMSS J031300.36-670839.3. It is found that calcium production in Population III stars is very sensitive to variations of the triple- &alpha, reaction rate and hence &delta, NN . We conclude that variations of the nucleon&ndash, nucleon interaction are constrained as - 0 . 002 &lt, &delta, NN &lt, 0 . 002 at the redshift z &sim, 20 , assuming that calcium in SMSS J031300.36-670839.3 originates from hydrogen burning in a massive Population III star.