易降解有机物及其施加方式对高粱吸收镉的影响

为探明易降解有机物及其施用方式对高粱吸收镉的强化效应,通过盆栽试验探讨了2 mmol·kg~(-1)草酸(OA)、2 mmol·kg~(-1)柠檬酸(CA)和1 g·kg~(-1)水溶性有机肥(DOF)分次(1～4次)施加对土壤中镉(Cd)的活性、高粱(Sorghum bicolor L.)生长及对Cd吸收的影响。结果表明:施加OA、CA和DOF提高了土壤中Cd的活性,且OA、CA分4次施加和DOF 1次施加时,土壤中DTPA-Cd含量最高,分别比CK显著增加了11%、30%和29%;OA、CA和DOF 1次施加对高粱生物量无显著影响,分2次施加则显著抑制了高粱生长,其中DOF处理的生物量较CK下降38%;OA、CA和DOF分2～3次施加促进了高粱对Cd的吸收,高粱根部、地上部中的Cd含量及富集系数显著高于CK;OA、CA分3次施加和DOF 1次施加时,高粱地上部分Cd积累量分别比CK显著增加了17%、30%和31%。总体来看,分3次施加CA对土壤Cd活化及高粱吸收Cd的效果最好。

Effect of biodegradable organic materials and application regimes on cadmium absorption in Sorghum bicolor L.

A pot experiment was conducted to investigate the effects of enhancement of biodegradable organic materials and their application regimes on the uptake of Cd by sorghum (Sorghum bicolor L.). Oxalic acid (OA), citric acid (CA), and dissolved organic fertilizer (DOF) were splitting applied at rates of 2 mmol·kg^-1, 2 mmol·kg^-1, and 1 g·kg^-1, respectively. The changes in available Cd in the soil and the growth and Cd accumulation in the shoots of the sorghum were determined. The results showed that four separate applications of CA and OA and a single application of DOF significantly increased the DTPA-Cd (DTPA extractable Cd) by 11%, 30%, and 29%, respectively, compared with that of the control (CK). Single applications of OA, CA, and DOF had no significant effect on the shoot biomass of sorghum, but two separate applications of these organic materials inhibited the growth of sorghum. Compared to CK, two separate applications of DOF significantly decreased the shoot biomass of sorghum by 38%, while the split applications of OA, CA, and DOF two or three times promoted Cd uptake by sorghum. Moreover, the Cd concentration in the roots and shoots of sorghum and the bioaccumulation factor were significantly higher than those of CK. Three separate applications of OA and CA and a single application of DOF significantly increased the Cd bioaccumulation in sorghum shoots by 17%, 30%, and 31%, respectively, compared with that of CK. Altogether, three separate applications of CA could be recommended for mobilization of Cd in soil when planting sorghum in Cd-contaminated soil.