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Global climate change, specifically rising temperature, can alter the molecular physiology of weedy plants. These changes affect herbicide efficacy and weed management. This research aimed to investigate the combined effect of heat stress (HS) and sublethal doses of herbicides (four active ingredients) on adaptive gene expression and efficacy of herbicide on Echinochloa colona (L.) Link (junglerice). Three factors were evaluated; factor A was E. colona generation (G0-original population from susceptible standard; G1 and G2 were progenies of recurrent selection), factor B was herbicide treatment (florpyrauxifen-benzyl, glufosinate-ammonium, imazethapyr, quinclorac and nontreated check) and factor C was HS (30 and 45 °C). The herbicides were applied at 0.125× the recommended dose. Recurrent exposure to HS, combined with sublethal doses of herbicides, favors the selection of plants less susceptible to the herbicide. Upregulation of defense (antioxidant) genes (APX: Ascorbate peroxidase), herbicide detoxification genes (CYP450 family: Cytochrome P450), stress acclimation genes (HSP: Heat shock protein, TPP: Trehalose phosphate phosphatase and TPS: Trehalose phosphate synthase) and genes related to herbicide conjugation (UGT: UDP Glucosyltransferase) was significant. The positive regulation of these genes may promote increased tolerance of E. colona to these herbicides. [ABSTRACT FROM AUTHOR]