施肥对Cd胁迫下小白菜生理生化特性和生物累积的影响

Effects of Cadmium on Physiological and Biochemical Characteristics and Bio-Accumulation of Pakchoi in Different Fertilizing

采用土培盆栽试验研究了在施化肥和有机肥的条件下，不同浓度Cd胁迫对小白菜生理生化特性及生物累积效应的影响。结果表明，在施肥的条件下，土壤中添加0～25mg·kg^-1的外源Cd时，小白菜生物量表现为Cd低浓度处理（≤5mg·kg^-1）时升高，高浓度处理（≥10mg·kg^-1）时降低的趋势；叶绿素含量也表现出低浓度（≤10mg·kg^-1）处理升高，高浓度（≥25mg·kg^-1）处理降低的趋势；Vc含量随Cd处理浓度的增大逐渐下降；MDA含量及Cd在小白菜体内的累积量与Cd处理浓度正相关，且根部Cd的累积量高于地上部。与化肥相比，有机肥在一定程度上可以缓解Cd对小白菜生物量、叶绿素、Vc、膜结构破坏等的毒害作用，降低土壤中Cd的生物有效性，因为施有机肥条件下小白菜对镉的吸收率较低。关于有机肥对Cd胁迫的缓解机理还需进一步研究。

Pot experiments were conducted to study the effects of cadmium on physiological, biochemical characteristics and bio - accumulation of pakchoi under chemical or organic fertilizing. The experimental results showed that when cadmium was added to the soil with levels between 0 mg · kg^-1 soil and 25 mg· kg^-1 soil, biomass of pakchoi increased at Cd amounts ≤ 5 mg· kg^-1 soil, but decreased when Cd was ≥10 mg· kg^-1 soil. Chlorophyll content of pakchoi increased at Cd amounts≤ 10 mg· kg^-1 soil, but decreased when Cd was≥25 mg· kg^-1 soil. Vc content of pakchoi decreased as the amount of cadmium increased. MDA content and cadmium concentration in pakchoi were positively correlated with the amount of cadmium applied to soil and cadmium concentration was higher in roots than in aerial part of pakchoi. The result also indicated that the toxic effect of Cd on pakchoi and the biological availability of soil Cd both reduced in the presence of organic fertilizer compare to chemical fertilizer due to the uptake efficiency of Cd by pakchoi was lower under organic fertilizer than chemical fertilizer conditions. More research is needed to study the mechanisms of the reduction of toxicity effect and Cd accumulation in pakchoi with the application of organic fertilizer.