The response of shoot accumulation of trace elements in Chinese cabbage to microclimate modification.

In three consecutive years of field experiments (1994-96), three different environmental conditions for the growth of Chinese cabbage (Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50) were established by using two cover treatments (T1 and T2) and a control uncovered cultivation (T0). The T1 [50 microm polyethylene cover; 20 degrees C air temperature; 61.9% relative moisture; 207 Wm(-2) irradiance] and T2 [a 17 gm(-2) non-woven fleece; 18 degrees C; 63.4%; 205 Wm(-2) gave rise to differences in environmental conditions with respect to T0 [14 degrees C; 57.5%; 237 Wm(-2)]. We analysed chloride (Cl), barium (Ba). rubidium (Rb) and tin (Sn) in the whole tops of experimental plants. Chloride removal was high for Brassica pekinensis but considerably lower for Rb, giving intermediate values for Ba and Sn. The influence of environmental factors under T1 increased trace-element removal and enhanced the usefulness for phytoremedation.