Selenium accumulation by sequentially grown wheat and rice as influencedby gypsum application in a seleniferous soil

摘要

A field experiment was conducted for 2 years on an alkaline calcareous seleniferous soil to study the effect of different levels of gypsum (0.2 - 3.2 t ha(-1)) applied to wheat only in the first year on Se accumulation by wheat (Triticum aestivum L.) - rice ( Oryza sativa L.) cropping sequence. With gypsum application, grain yield of both rice and wheat crops increased by 0.4 - 0.5 t ha(-1); the increase in straw yield was 0.4 - 1.1 t ha(-1). Significant reduction in Se accumulation by wheat was observed with gypsum application up to 0.8 t ha(-1) and its residual effect was evident on the following crops for 2 years. Reduction in Se accumulation varied from 53 to 64% in wheat grain, 46 to 49% in wheat straw, 35 to 63% in rice grain and 36 to 51% in rice straw with an application of gypsum at 0.8 t ha(-)1. A corresponding increase in S concentration was observed. In the gypsum-treated plots, the ratio of S:Se increased by 6 - 8 times in wheat and 3 - 6 times in rice. Reduction in Se accumulation by crop plants through gypsum application may help in lowering the risk of Se over-exposure of animals and humans that depend on diet materials grown on high selenium soils.