Abstract: Field experiments were carried out to investigate the effects of exogenous selenium (0.0, 1.0 and 2.5 mg/L) on
the growth, selenium speciation and selenium uptake of Brassica juncea var. tumida Tsen et Lee. The results showed that
foliar spraying of selenium (1.0 mg/L) increased the growth of Brassica tumida Tsen et Lee but its effect was not significant
(P > 0.05). Foliar spraying of selenium (Se) reduced the nitrate content of Brassica juncea var. tumida Tsen et Lee, while it
increased free amino acids, VC and reducing sugar by 40.41%, 13.36% and 46.73% compared with the control, respectively.
Foliar selenium application increased the concentrations of total and organic Se by 46.1%–193.9% and 74.0%–271.5%
compared with the control, respectively, and this effect was concentration dependent. The transformation rate of organic
selenium in Brassica juncea var. tumida Tsen et Lee applied with 1.0 and 2.5 mg/L Se significantly increased by 19.33% and
23.57% compared with the control, respectively. Organic selenium was the dominant selenium species in Brassica juncea
var. tumida Tsen et Lee. The contents of total and organic selenium in Brassica juncea var. tumida Tsen et Lee revealed a
positive correlation with the exogenous selenium concentration (P < 0.01).

Key words: exogenous selenium, selenium speciation, selenium uptake, selenium transformation, Brassica juncea var. tumida Tsen et Lee