Formal Degrees and Parabolic Induction: the Maximal Generic Case

We study the compatibility of the formal degree conjecture and the parabolic induction process in the simplest nontrivial case for quasi-split $p$-adic groups. For a generic discrete series $\pi$ induced from an irreducible supercuspidal $\sigma$ of a maximal Levi subgroup, we compute the quotient $d(\pi )\mathrm{/}d(\sigma )$ of formal degrees under some assumptions. As an application, we verify the conjecture for discrete series of split ${\mathrm{G}}_2$ supported on maximal Levi subgroups.