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The Apache Point Observatory Galactic Evolution Experiment (APOGEE) hasobserved $\sim$600 transiting exoplanets and exoplanet candidates from\textit{Kepler} (Kepler Objects of Interest, KOIs), most with $\geq$18 epochs.The combined multi-epoch spectra are of high signal-to-noise (typically$\geq$100) and yield precise stellar parameters and chemical abundances. Wefirst confirm the ability of the APOGEE abundance pipeline, ASPCAP, to derivereliable [Fe/H] and effective temperatures for FGK dwarf stars -- the primary\textit{Kepler} host stellar type -- by comparing the ASPCAP-derived stellarparameters to those from independent high-resolution spectroscopiccharacterizations for 221 dwarf stars in the literature. With a sample of 282close-in ($P<100$ days) KOIs observed in the APOGEE KOI goal program, we find acorrelation between orbital period and host star [Fe/H] characterized by acritical period, $P_\mathrm{crit}$= $8.3^{+0.1}_{-4.1}$ days, below which smallexoplanets orbit statistically more metal-enriched host stars. This effect maytrace a metallicity dependence of the protoplanetary disk inner-radius at thetime of planet formation or may be a result of rocky planet ingestion driven byinward planetary migration. We also consider that this may trace a metallicitydependence of the dust sublimation radius, but find no statisticallysignificant correlation with host $T_\mathrm{eff}$ and orbital period tosupport such a claim.

Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances