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【目的】在人工模拟镉污染土壤条件下,讨论了叶面喷施Fe对番茄Cd积累及化学形态的影响,旨在为镉污染土壤上番茄的安全生产提供理论依据。【方法】采用土培试验研究了在重金属Cd(10 mg/kg)污染条件下,叶面喷施不同浓度Fe(0、200和400μmol/L,Fe SO4·7H2O)对2个番茄品种(‘4641’和‘渝粉109’)生长、光合特性、品质及果实Cd形态和Cd积累量的影响。【结果】叶面喷施Fe提高了番茄的根、茎、叶、果实干重及植株总干重,增幅分别为20.4%~48.6%、13.3%~56.0%、16.0%~63.1%、9.8%~16.5%和21.6%~40.3%,随着喷施Fe浓度的增加,番茄各部位干质量及总干质量呈先增加后降低的趋势,比较两个番茄品种,‘4641’耐Cd性更强,而‘渝粉109’对Fe的反应更为敏感;随着喷施Fe浓度的增加,2个番茄品种的叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)呈先增加后降低趋势,在Fe 200μmol/L时最大,品种‘4641’的Pn、Gs和Tr较对照分别增加了8%、11%和2.9%,而‘渝粉109’较对照分别增加了28.7%、15.5%和18.8%。而喷Fe处理却降低了番茄叶片胞间CO2浓度(Ci),比较2个供试番茄品种,‘4641’光合作用和蒸腾作用强度均高于‘渝粉109’;喷Fe提高了2种番茄果实的硝酸盐含量以及渝粉‘109’还原糖含量,降低了‘渝粉109’果实氨基酸含量,喷施高浓度Fe(400μmol/L)能提高2种番茄果实Vc含量,与对照相比,‘4641’和‘渝粉109’果实硝酸盐增加的幅度分别为18.1%~22.2%、2.3%~22.0%,Vc较对照分别增加了8.2%和13.2%;番茄果实中Cd的主要存在形态为残渣态,其次为盐酸提取态,去离子水提取态和乙醇提取态所占比例较小,残渣态Cd(FR)和盐酸提取态Cd(FHCl)为活性偏低形态Cd,占Cd提取总量的70.8%,去离子水提取态(FW)和乙醇提取态(FE)为活性较高形态Cd,仅占Cd提取总量的11.8%,有效地抑制了Cd的毒害作用。叶面喷施Fe降低了番茄果实各形态镉含量;番茄中Cd主要积累在叶和茎中,而果实和根的积累量较少;喷Fe降低了番茄叶、根、茎、果实的Cd含量,降低幅度分别为7.1%~21.9%、35.6%~50.4%、13.0%~37.0%和2.8%~8.2%,但喷施高浓度Fe(400μmol/L)相比低Fe(200μmol/L)时的番茄各部位Cd含量有所增加,无论是非否喷施Fe,叶、茎、果实中的Cd积累量以及总Cd积累量总是以‘4641’>‘渝粉109’,表明在Cd污染土壤上种植‘4641’较‘渝粉109’风险更大。【结论】叶面喷施适量Fe能够促进番茄的光合作用和蒸腾作用,提高了番茄各部位的干重,降低了Cd对番茄的毒害效应,同时减少了番茄各部位Cd含量。
【Objective】 The objective of this study was to investigate the effect of foliar application of Fe on Cd accumulation and chemical speciation in tomato plants under artificial simulated soil contamination with cadmium so as to provide a theoretical basis for the safe production of tomato on Cd-contaminated soil. 【Method】 The effects of different concentrations of Fe (0, 200 and 400 μmol / L, Fe SO 4 .7H 2 O) were sprayed on two tomato cultivars (’ 4641 ’and’ Yu Fen 109 ’) growth, photosynthetic characteristics, quality and Cd content and Cd accumulation in fruit. 【Result】 Leaf application of Fe increased the dry weight of roots, stems, leaves and fruits and total dry weight of the plants by 20.4% -48.6%, 13.3% -56.0%, 16.0% -63.1%, 9.8% ~ 16.5% and 21.6% ~ 40.3% respectively. With the increase of spraying Fe concentration, the dry weight and total dry weight of different parts of tomato increased at first and then decreased. Compared with two tomato cultivars, the ’4641’ , While ’Yufen 109’ was more sensitive to Fe. The net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of two tomato cultivars were increased with increasing Fe concentration Pn, Gs and Tr in ’4641’ increased by 8%, 11% and 2.9% respectively compared with the control, while ’Yufen 109’ increased by 28.7% compared with the control %, 15.5% and 18.8%. While spraying Fe treatment reduced the intercellular CO2 concentration (Ci) of tomato leaves. Compared with two tested tomato cultivars, the photosynthesis and transpiration intensity of ’4641’ were higher than that of ’Yu Fen 109’ The content of nitrate in fruit and the reducing sugar content in ’109’ of Yufen decreased the amino acid content of fruit of ’Yufen 109’. Spraying high concentration of Fe (400μmol / L) could increase Vc content of two kinds of tomato fruit. Compared with the control, The results showed that the nitrate accumulation in fruits of ’4641’ and ’Yufen 109’ increased by 18.1% -22.2%, 2.3% -22.0%, Vc increased by 8.2% and 13.2% compared with the control respectively. The main existing forms of Cd in tomato fruits were Residue state, followed by hydrochloric acid extract, deionized water extract and ethanol extract accounted for a small proportion of residual state Cd (FR) and hydrochloric acid extractable state of Cd (FHCl) activity is low form Cd, accounting for the total amount of Cd extraction , 70.8% of deionized water (FW) and ethanol extract (FE), respectively, accounted for only 11.8% of the total amount of Cd extracted, which effectively inhibited the toxicity of Cd. Leaf foliar application of Fe reduced the content of Cd in tomato fruit. Cd in tomato mainly accumulated in leaves and stems, while accumulation of fruits and roots was less. Fe addition reduced Cd content in leaves, roots, stems and fruits , Decreased by 7.1% -21.9%, 35.6% -50.4%, 13.0% -37.0% and 2.8% -8.2%, respectively. However, when the concentration of Fe was low (400μmol / L) The content of Cd in different parts of tomato increased with or without spraying. The accumulation of Cd in leaves, stems and fruits and the total Cd accumulation were always “4641”> “Yufen 109” On planting ’4641’ than ’Yu powder 109’ at greater risk. 【Conclusion】 Leaf application of appropriate amount of Fe can promote the photosynthesis and transpiration of tomato, increase the dry weight of various parts of tomato, reduce the toxic effect of Cd on tomato and reduce the content of Cd in different parts of tomato.