The 12-oxo-phytodienoic acid reductase (OPR) is a key enzyme in jasmonic acid (JA) biosynthesis. Previously, we reported the presence of 13 OPR isogenes (OsOPR1-13) in rice. OsOPRs phylogenetically belong to two subgroups, OPRI and OPRIl. OsOPR13 is assigned to the second subgroup, which is involved in JA biosynthesis, while the others are found in the first subgroup. Here, we systematically investigated transcript levels of OsOPRs in various tissues and against diverse environmental stresses. Each gene was differentially involved in flower maturation, showing a tissue-specific response. OsOPR1, OsOPR2, and OsOPR13 were also active in responses to wounding, a fungal elicitor (chitosan), salt, UV-C irradiation, $H_2O_2$, and ozone exposure. In the case of JA-responsive OsOPRs (OsOPR1, OsOPR2, OsOPR6, OsOPR10, and OsOPR13), co-application of JA and SA suppressed jasmonate-induced transcript levels and delayed OsOPR10 expression. We also investigated the biochemical properties of OsOPR1 and found a flavin cofactor with optimal activity at pH7.8 and values of 0.048 $min^{-1}$ $k_{cat}$ and 8.33 ${mu}M$ $K_m$ for (9S,13R)12-oxo-phytodienoic acid. Here, we discuss the role of OsOPRs in stress responses and floral development.