Root-secreted phytochemicals mediate multiple interactions in the rhizosphere. The root exudation process can be altered by various biotic factors, including pathogenic and non-pathogenic microbes, and abiotic factors like temperature and soil moisture. It has been suggested that root secretion of specific flavonoids is influenced by diual rhythms (by light or dark) but a comprehensive analysis of the overall secretion of phytochemicals in response to diual rhythms has not been studied. In this study, we analyzed the effect of light/dark cycles on root exudation profiles using Arabidopsis as a model plant. Our results reveal that the root secretion of phytochemicals is partly regulated by the diual light cycle and follows two main pattes of secretion: (1) the large majority of phytochemicals in the exudates showed no diual patte in their secretion, and (2) a few compounds showed a diual patte in their secretion: three compounds increased in secretion only under light; two compounds increased in secretion only while it was dark; and two compounds increased in secretion during the transition from dark to light. Root-specific ABC transporters have been implicated in root exudation; an analysis of the gene expression pattes of ABC transporters in the roots of Arabidopsis at specific time points revealed that none of the ABC transporters followed a diual expression patte, suggesting that they are expressed constantly during the day and night. Similarly, we analyzed the expression in roots of genes involved in secondary metabolite biosynthesis and found that some of the genes involved in phenylpropanoid and glucosinolate biosynthesis (i.e. 4-coumarate-CoA ligases (4CL1 and 4CL2), flavonol synthases (FS1 and FS2), and CYP79B3) followed distinct diual expression pattes. Overall, we have discovered that while root exudation of the majority of phytochemicals is constitutive, the secretion of a few compounds follows a diual rhythm, which is in accordance with the expression of some genes involved in secondary metabolism.