Alternation of light/dark period priming enhances clomazone tolerance by increasing the levels of ascorbate and phenolic compounds and ROS detoxification in tobacco (Nicotiana tabacum L.) plantlets.

•The pretreatment with alternation of light/dark periods (AL) reduced the inhibitory effect of clomazone on PSII.•AL could promote photorespiration via post-illumination burst (PIB) effects.•AL increased the activity of antioxidant enzymes and the levels of ascorbate and phenolic compounds.•AL decreased H2O2 and starch grain accumulation and programmed cell death (PCD) levels.