2価鉄によるクワ苗の6価クロム障害の軽減効果

抄録

Abatement of the obstruction by Cr⁶⁺ to the mulberry growth was significant due to the addition of Fe²⁺ into the hydroponic solution. Compared with the blank samples, the visibleobstruction to the mulberry growth was severe, slight and invisible corresponding to thecharged concentration ratios of Fe²⁺ / Cr⁶⁺, 1/1, 3/1 and 5/1 (w/w), respectively. Meanwhile, the factors such as the shoot length, number of leaf number, chlorophyll concentration, dry weight growth, relative growth rate (RGR) and net assimilation rate (NAR) of mulberry were also affected significantly by adding Fe²⁺. These data supported the results obtained by the visual observation. Therefore, it was considered that the abatement of Cr6+ obstruction to the mulberry growth was probably resulted from two factors. The first one is that Cr6+ was reduced to Cr³⁺, which lightly obstructed the mulberry growth, due to the addition of Fe²⁺. The second one is that the residue of Cr⁶⁺ was just kept in the mulberry root after absorption, because the distribution of Cr⁶⁺ in the organs showed that a small amount of Cr⁶⁺ immigrated to the organs above the ground (the concentrations of Cr in the stern and the leaf was much lower than those without adding Fe²⁺). On the other hand, more than 3 times weight of Fe²⁺ to Cr6+shouId be required for thoroughly abating the obstruction of Cr⁶⁺..Key words: divalent iron ion, hexavalent chromium ion, mulberry, growth obstruction, ameliorative effects