铁对番茄镉积累及其化学形态的影响

Effect of Iron on Accumulation and Chemical Forms of Cadmium in Tomato

采用番茄盆栽试验研究了在重金属Cd（10 mg · kg-1）污染条件下，叶面喷施不同浓度（0、200 和400 μmol · L-1）Fe（FeSO4 · 7H2O）对番茄‘4641’和‘渝粉109’生长、光合特性、抗氧化酶活性及番茄体内Cd 形态和积累量的影响。结果表明，喷施Fe 后，番茄果实、根、茎、叶干质量和植株总干质量，以及Cd 含量和积累量在2 个品种之间的差异达到了显著水平。Fe 处理显著增加了2 个番茄品种的果实、根、茎、叶及植株总干质量。随Fe 浓度增加，番茄叶片Pn、Gs 和Tr 以及‘渝粉109’POD 活性、‘4641’叶CAT 活性先增加，然后降低；而叶片Ci 以及‘渝粉109’叶SOD 活性则先下降然后回升。番茄果实中各形态Cd 含量的顺序为：残渣态Cd（FR）〉 盐酸提取态Cd（FHCl）〉 乙醇提取态Cd（FE）〉 氯化钠提取态Cd（FNaCl）〉 乙酸提取态Cd（FHAc）〉 去离子水提取态Cd（FW）。适量的Fe（200 μmol · L-1）减少了番茄果实中各形态Cd 含量，但高量Fe（400 μmol · L-1 ）增加了‘4641’果实中FHCl、FR 以及‘渝粉109’果实中FE、FNaCl、FR 和Cd 总提取量。番茄各部位Cd 积累量的顺序为：叶 〉 茎 〉 果实 〉 根。叶面喷施Fe（200 μmol · L-1）使番茄叶、茎、根和果实中的Cd 含量相比对照处理分别降低了7.1% ~ 21.9%、35.6% ~ 50.4%、13.1% ~ 37.0%和2.8% ~ 8.2%。供试2 个番茄品种，无论喷Fe 与否，果实Cd 含量、果实Cd 积累量和植株Cd 总积累量均为‘4641’〈‘渝粉109’。

Pot experiments were carried out to investigate the influence of different iron（Fe）levels （0,200 and 400 μmol · L-1）on the plant growth,activities of antioxidant enzymes,accumulation and chemical forms of cadmium（Cd）in tomato when exposed to Cd（10 mg · kg-1）. The results showed that dry weights of fruit,roots,stem,leaf and plant,and concentrations and accumulation of Cd significantly differed between two varieties of tomato. Dry weights of fruit,roots,stem,leaf and plant increased in the presence of Fe. Photosynthetic rate（Pn）,stomatal conductance（Gs）and transpiration rate（Tr）in both varieties,and activity of peroxidase（POD）in‘Yufen109’,and activity of catalase（CAT）in‘4641’ increased at first,and then decreased with increasing levels of Fe,while intercellular carbon dioxide concentration（Ci）in both varieties,activity of superoxide dismutase（SOD）in‘Yufen109’decreased at first,and then increased with increasing levels of Fe. The contents of chemical forms of Cd in fruit of tomato were in order of residual Cd（FR）〉 hydrochloric acid-extractable Cd（FHCl）〉 ethanol-extractable Cd（FE）〉 sodium chloride-extractable Cd（FNaCl）〉 acetic acid-extractable Cd（FHAc）〉 deionized water-extractable Cd（FW）. All chemical forms of Cd significantly decreased after the application of adequate Fe（200 μmol · L-1）compared to the control. However,FHCl and FR of‘4641’,and the total extractable Cd,FE,FNaCl and FR of‘Yufen109’increased at 400 μmol · L-1 Fe treatment. Cadmium accumulations in tomato were in order of leaf 〉 stem 〉 fruit 〉 roots. Cadmium concentrations in leaf, stem,roots and fruit of both varieties decreased by 7.1%–21.9%,35.6%–50.4%,13.1%–37.0% and 2.8%–8.2% in the presence of Fe when exposed to Cd,respectively. Cadmium concentrations,and Cd accumulation in fruit and plant were in order of ‘4641’〈‘Yufen109’in the presence or absence of Fe.