根区通氧状况对水稻幼苗生长及吸收镉的影响

Effects of root zone oxygenation on growth and Cd accumulation in paddy rice(Oryza sativa L.)

采用水培的方法研究了根区通氧状况对水稻根系结构、根系泌氧、根表铁膜生成以及水稻耐受、吸收Cd的影响。水培条件下,根区氧处理对水稻幼苗的生长产生了一定的影响,缺氧条件下的水稻根的伸长量降低,生物量增加,直径增粗,根系泌氧量增加,并降低幼苗对Cd的吸收。当培养溶液Cd2+浓度为1.0 mg/L时,缺氧处理相对于通氧处理,根表吸附的Cd降低了85.5%,地下部分吸收的Cd降低了35%,转运到地上部分的Cd降低了58%。根表铁膜对Cd的吸收和转运也有一定的抑制作用,但其作用因环境中Cd2+浓度和根区通氧状况而异。在根区通氧充分的培养条件下,水稻幼苗铁膜对较高浓度Cd2+(1.0mg/L)的吸收和转运起着重要的作用,DCB-Cd占根系吸收Cd的50%,茎叶对Cd的吸收显著降低(p<0.05)。研究表明在缺氧胁迫下,根系结构本身(如根表通透性降低)是影响水稻吸收Cd的重要因素。

The effects of root zone oxygenation on rice （ Oryza sativa L. ） roots architecture, radial oxygen loss （ ROL）, iron plaque formation and Cd accumulation were investigated in aerated and stagnant nutrient solutions. The results indicated that seedlings grown in stagnant solutions developed shorter and thicker roots but higher biomass and ROL rate than those in aerated ones. In addition, Cd accumulation was greatly inhibited in tissues of stagnant rice seedlings. When exposed to 1. 0 mg/L Cd^2＋ solutions, Cd adsorbed on stagnant root surface was decreased by 85. 5%, while Cd accumulated in the same roots and shoots reduced by 35% and 58% respectively, comparing with those on and in aerated ones. Iron plaque could inhibit Cd uptake by and translocation in rice seedlings by adsorbing 50% of the total Cd accumulated in root system, but only in conditions with sufficient root-zone-oxygen and higher Cd concentration （ 1.0 mg/ L）. As for in condition of root zone with deoxygenation, root structure （e. g. reduced root permeability） per se may be more important than Fe plaque to affect Cd uptake in rice seedlings.