旺盛期烟草对镉富集敏感性研究

采用盆栽试验方法，揭示了旺盛期烟草（云烟99）对镉的富集特点以及光合等生理指标对镉胁迫的响应.结果表明：当土壤镉含量分别为4.43，7.94，17.33和49.79mg/kg时，烟草茎、叶及地上部镉的富集系数（植物镉含量与土壤镉含量的比值）均大于1，转移系数（地上部镉含量与根镉含量的比值）也大于1，但镉含量未达到镉超富集植物的临界含量标准100mg/kg.当土壤镉含量为4.43mg/kg时，烟草的耐性较强.当土壤镉含量大于7.94mg/kg时，烟草的生物量、叶片光合色素含量、净光合速率、蒸腾速率、气孔导度和SOD活性均显著下降（P<0.05），胞间CO₂浓度和MDA含量显著提高（P<0.05）.旺盛期烟草对镉富集比较敏感，建议烟草的种植要远离镉污染土壤或镉背景值较高的土壤.

Sensitivity of Nicotiana tabacum L. accumulating cadmium at its vigorous growth stage

Pot experiments were conducted to reveal the characteristics of cadmium (Cd) accumulation in Nicotiana tabacum L. (Yunyan 99) at vigorous stage and the response of physiological indexes like photosynthesis to Cd stress. The results showed that the enrichment factor (ratio of Cd concentration in plant to soil) and translocation factor (ratio of Cd concentration in shoot to root) of Cd in tobacco stems, leaves and shoots were all greater than 1, but the Cd concentration of them did not reach the critical content standard of 100mg/kg in the treatments of 4.43mg/kg, 7.94mg/kg, 17.33mg/kg or 49.79mg/kg Cd in soils. When the Cd concentration in soil was 4.43mg/kg, the tolerance of tobacco was stronger. When soil Cd content was higher than 7.94mg/kg, tobacco biomass, photosynthetic pigment content, net photosynthetic rate, transpiration rate, stomatal conductance and SOD activity were significantly decreased (P<0.05), while intercellular CO₂ and MDA content was significantly increased (P<0.05). It is suggested that tobacco is sensitive to Cd accumulation in vigorous period, and should be planted far away from Cd contaminated soil or soil with high Cd background value.