Effects of foliar application of melatonin on selenium accumulation in medicinal plant <i>Perilla frutescens</i>

Abstract Application of melatonin (MT) can promote selenium (Se) uptake in crops. To enhance Se accumulation in the medicinal plant Perilla frutescens , a pot experiment was carried out to investigate the impact of foliar spraying MT on Se uptake in P. frutescens . The root and shoot biomass of P. frutescens were increased by MT to some extent. MT at 150 μmol/L displayed the maximum biomass, which increased the root and shoot biomass by 53.37% and 39.09%, respectively, compared to the control. MT also increased the photosynthetic pigment contents in P. frutescens to a certain extent, while it had no significant effect on the chlorophyll a / b ratio. MT increased the antioxidant enzyme activities and soluble protein content of P. frutescens . In addition, MT at 150 and 200 μmol/L increased the root Se content, shoot Se content, bioconcentration, and translocation factor of P. frutescens , while at 25, 50, and 100 μmol/L had no significant effects on these parameters. Compared to the control, MT at 150 and 200 μmol/L increased the root Se content by 8.95% and 9.36%, respectively, and increased the shoot Se content by 19.35% and 13.85%, respectively. Moreover, root Se content, shoot biomass, chlorophyll a content, and root biomass were closely associated with shoot Se content. Therefore, foliar application of 150 and 200 μmol/L MT can promote the growth and Se uptake of P. frutescens .