Abstract: Enhancing the enrichment capacity of selenium (Se) in crops is of great significance to improve soil Se utilization efficiency and optimize the production of Se-enriched crops. We conducted a pot experiment to examine the role of exogenous plant hormones (jasmonic acid, JA; salicylic acid, SA) in enhancing Se enrichment capacity of pak choi (Brassica chinensis L.). There were five treatments: control (CK), 50 μmol·L^-1 JA (JA50), 100 μmol·L^-1 JA (JA100), 50 μmol·L^-1 SA (SA50), and 100 μmol·L^-1 SA (SA100). We measured Se content, cadmium (Cd) content, biomass, chlorophyll fluorescence, MDA content, and antioxidant enzymatic activities of pak choi after harvest. We found that shoot Se content and root Se content under plant hormone treatments increased by 54.7%-229.1% and 175.0%-276.8% relative to CK, respectively, and that shoot Se content and accumulation were significantly higher in JA treatment groups than that in SA treatment groups. The shoot Cd content and accumulation under plant hormone treatments decreased by 26.3%-63.2% and 38.5%-72.1% relative to CK, respectively. Shoot Cd content and accumulation of the JA treatment groups were much lower than that of the SA treatment groups. With regard to fluorescence, F_v′/F_m′, Φ_PSII, and q_P were significantly lower, whereas NPQ was significantly higher in plant hormone treatments compared with that in CK, indicating that plant hormone treatments significantly decreased the activity of PSII. Plant hormone treatments significantly increased leaf MDA content, causing heavy lipid peroxidation. In summary, foliar spraying of 50 or 100 μmol·L^-1 JA or SA can effectively enhance the enrichment capacity of pak choi to soil Se and reduce shoot Cd accumulation. These ameliorative effects of JA are greater than that of SA.

Key words: exogenous jasmonic acid, exogenous salicylic acid, selenium accumulation, chlorophyll fluorescence.