水稻镉高积累材料不同生育期镉积累变化特征研究

Cadmium Accumulation in High Cadmium-Accumulating Rice Cultivars at Different Growth Stages

为降低土壤Cd含量,以水稻Cd高积累材料Lu527-8和Lu17-9为研究对象,普通材料Lu527-4为对照,采用土培盆栽试验,分析其各生育期生物量、Cd积累量、Cd积累速率等指标,探讨水稻Cd高积累材料的Cd富集特性。结果表明:Lu527-8和Lu17-9地上部和整株生物量随生育期的延长呈上升趋势且差异显著,其在分蘖-拔节期上升幅度较小,而在拔节-成熟期急剧上升。Lu527-8和Lu17-9地上部和整株生物富集量系数随生育期的延长显著上升且在灌浆期后差异不显著。Lu527-8和Lu17-9地上部和整株Cd积累速率随生育期的延长先升高后降低且在灌浆期达最大值,其地上部Cd积累速率分别为Lu527-4的2.43倍和2.24倍。整株Cd积累速率分别为Lu527-4的2.33倍和2.10倍。Lu527-8和Lu17-9地上部和整株Cd积累量随生育期的延长呈上升趋势且在拔节-灌浆期显著上升,Lu527-8和Lu17-9地上部Cd积累量在灌浆期分别达359.28、331.22μg·株-1,为Lu527-4的2.44倍和2.25倍。整株Cd积累量在灌浆期分别达1 374.35、1 240.72μg·株-1,为Lu527-4的2.33倍和2.10倍。Lu527-8和Lu17-9地上部和整株阶段性Cd积累量在拔节-抽穗期和抽穗-灌浆期显著高于其他生育阶段,其整株阶段性Cd积累量在拔节-抽穗期和抽穗-灌浆期分别占整个生育时期的15.30%、40.45%和39.70%、20.74%。Lu527-8和Lu17-9地上部和整株净化率随生育期的延长显著上升且在灌浆期后趋于稳定,其地上部净化率在灌浆期时分别达0.82%和1.25%,其整株净化率分别达4.88%和4.39%,为Lu527-4的2.44倍和2.21倍。高Cd条件下,水稻Cd高积累材料对Cd具有较强的吸收和积累能力,是一种理想稳定的Cd富集材料,且灌浆期为水稻Cd高积累材料最佳收获时期。

With the development of agriculture and industry, a large number of pollutants containing cadmium(Cd) have entered the soils.High contents of Cd in soil usually affect plant growth and elevate plant Cd contents, thus causing harm to human health through food chain.Therefore, reducing soil Cd content is critical. Here, a pot experiment was designed to evaluate the Cd accumulation characteristics of rice cultivars with high Cd accumulation at different growth stages. Two high Cd-accumulating rice cultivars(Lu527-8 and Lu17-9) screened earlier were used with common variety Lu527-4 as control. With growth period prolonged, a significant increase(P<0.05) was observed in shoot and whole plant biomass of two high Cd-accumulating rice cultivars(Lu527-8 and Lu17-9) in high Cd soil. The biomass increase was smaller at tillering-jointing stage while greater at jointing-maturity stage. With growth period prolonged, Cd absorption by both high Cd-accumulating cultivars(Lu527-8 and Lu17-9) was higher than that of the control(Lu527-4) at each growth stage(P<0.05). Cadmium accumulation rates of both high Cd-accumulating cultivars reached a maximum at the filling stage. The shoot Cd accumulation rates of rice Lu527-8 and Lu17-9 were respectively 2.43 and 2.24 times higher than that of the control(Lu527-4) at filling stage. The Cd accumulation rates of the whole plant were 2.33 and 2.10 times higher for Lu527-8 and Lu17-9 at filling stage, respectively, compared with that of control(Lu527-4). The Cd accumulation in shoot of high Cd- accumulating cultivars(Lu527-8 and Lu17-9) with high Cd treatments reached359.28 and 331.22 μg·plant-1at filling stage, which was respectively 2.44 and 2.25 times higher than that of the control(Lu527-4). The Cd accumulation in whole plant were 1 374.35 and 1 240.72 μg·plant-1for Lu527-8 and Lu17-9 at filling stage, which was 2.33 and 2.10 times higher than that of the control(Lu527-4), respectively. The high Cd-accumulating cultivars accumulated significantly higher Cd at jointing-heading and heading-filling stages than other stages. During jointing-heading and heading-filling periods, Cd accumulation by rice cultivar Lu527-8 respectively accounted for 15.30% and 40.45% of the whole growth period, while 39.70% and 20.74% for rice culti-var Lu17-9. The purification rate(PR) of soil Cd by shoot and whole plant increased significantly with increasing growth period before the filling stage(P<0.05). At filling stage, the PR of shoot was 0.82% and 1.25% for Lu527-8 and Lu17-9, while 4.88% and 4.39% for the whole plants, which was 2.44 and 2.21 times that of the control(Lu527-4), respectively. The present results show that high Cd-accumulating rice cultivars have great ability to accumulate and purify Cd from soils contaminated by high Cd, and that the filling stage is the optimum time for plant harvest for the purification purpose.