Catalyzes the oxidation of cytokinins, a family of N(6)-substituted adenine derivatives that are plant hormones, where the substituent is an isopentenyl group (PubMed:15976269). Is a major QTL involved in grain yield (PubMed:15976269). Modulates the number of reproductive organs by regulating the cytokinin accumulation in inflorescence meristems (PubMed:15976269, PubMed:28337744). Acts as negative regulator of panicle branching (PubMed:15976269, PubMed:28337744). A + H2O + N(6)-dimethylallyladenine = 3-methyl-2-butenal + adenine + AH2 Monomer. Mostly expressed in leaves, culms, inflorescence meristems, and flowers, especially in vascular tissues. Glycosylated. Enhanced grain production and higher cytokinin levels in inflorescence meristems. Belongs to the oxygen-dependent FAD-linked oxidoreductase family. Truncated N-terminus. Truncated N-terminus.