Characterizing Se transfer in the soil-crop systems under field condition

Abstract

A comparison was performed between plant species to study Se accumulation and translocation in the crops under field condition. Wheat, rice and canola were sampled with respective cultivated soils from the Yangtze River Delta area. The concentrations of total Se and bio-available Se and a number of parameters (N, P, S, Fe, Ca, Mg, Al, K, Mn, pH and organic carbon) were analyzed, and the net translocation coefficients of Se in the soil-crop systems were calculated. The concentrations of Se in plants significantly differed between crop species, in spite of concentrations of total Se and bio-available Se and related parameters in the soils showing no significant difference among the wheat, rice and canola sampled sites. With regard to the seeds, wheat exhibited significantly higher Se concentration than rice and canola; whereas for the straw and root, wheat showed lower Se concentration than canola and rice. The net translocation coefficients of Se in different soil-crop systems exhibited different patterns, suggesting that the difference is mainly caused by a discrepancy in Se translocation from straw to grain. Wheat has a weaker capability to accumulate Se compared with rice and canola, but a significantly stronger capability to transport Se from its straw to seed. These differences might be related to the influence of S on Se differences, comparing the biochemical behavior and transport of S and Se in plants of different plant species. Selenium follows sulfur during accumulation in wheat and rice because both elements are accumulated in plant tissues mainly in the form of amino acids; whereas in canola, the influence of S on Se accumulation is not as obvious as in wheat and rice because the seeds contain more non-amino acid organic S compounds.