Role of plant growth regulators is one of the current scientific areas of research and it more or less depends on the area of implementation. Now in recent times, application of plant growth regulators or PGR is applying in the field for getting a high range of yield. This study discusses a wide range of plant growth regulators and their application in two major crop plants- Rice and maize. Result of various enzymatic activities and also influence of various other promoters has been discussed efficiently to get a fundamental idea about the role of different PGR and PGP (Plant Growth Promoter). Activity of various types of bacterial species has also been included in this study to get a precise knowledge about plant growth regulators and their roles in yield. Different morphologically distinct variables of rice and maize have been taken for the study and their morphological changes have been addressed. The results which have been obtained from two distinct genus also give different results. In case of rice, treatment was arranged in a split plot design with the aid of four replications and in case of maize changes of activity of RE 1 and RE17 expression has been effectively calculated Keyword : PGP, enzymatic activities, Rice and maize, morphological changes, RE1, RE17