Effects of indole acetic acid on the growth and selenium absorption characteristics of Cyphomandra betacea seedlings

To study the effects of indole acetic acid (IAA) on the growth and selenium (Se) absorption of fruit tree, a pot experiment was conducted to study the effects of different concentrations involved in the spraying of 0 (the control), 30, 60, 90, and 120 mg/L IAA on the growth and Se uptake of C. betacea seedlings. The concentrations of 30, 60, and 90 mg/L IAA increased the various organs’ biomass and net photosynthetic rate of C. betacea seedlings compared to the control, while the concentration of 120 mg/L IAA had no significant effect on that. Only the concentration of 60 mg/L IAA increased the chlorophyll (chlorophyll a, chlorophyll b, total chlorophyll) contents in C. betacea seedlings compared to the control. The concentrations of 30, 60, and 90 mg/L IAA also increased the antioxidant enzymes’ (superoxide dismutase, peroxidase, and catalase) activities and soluble protein content of C. betacea seedlings compared to the control. For Se content, compared to the control, the concentrations of 60 and 90 mg/L IAA increased the Se contents in roots, stems, leaves, and shoots of C. betacea seedlings, and also enhanced the Se bioconcentration factor. Therefore, spraying IAA with the appropriate concentration (60–90 mg/L) could promote the C. betacea seedlings’ growth and Se absorption, and the best concentration was 60 mg/L IAA.