叶喷植物激素提高蓖麻对镉污染土壤修复效果的作用机制

Mechanism of Leaf Spraying Phytohormones to Improve the Remediation Efficiency of Castor on Cadmium-contaminated Soil

    摘要
  • 摘要:
    目的 探究喷施外源植物激素（脱落酸ABA和水杨酸SA）调控耐性植物蓖麻修复镉（Cd）污染土壤的效果及作用机制，阐明外源植物激素在土壤－植物体系中调控Cd迁移转化方面的差异。
    方法 本文以蓖麻（Ricinus communis L.）为供试植物开展盆栽实验，分别喷施0.1 mmol L−1（SA1）和0.8 mmol L−1（SA2）的SA以及1 µmol L−1（ABA1）和20 µmol L−1（ABA2）的ABA于植物叶面，并以蒸馏水做对照（CK），探究外源植物激素对蓖麻生长、光合色素、Cd转运系数（TF）及根际土壤理化性质、可溶性有机质（DOM）性质和根际土壤Cd赋存形态的影响。
    结果 ① ABA处理显著促进蓖麻生长（生物量较CK提升6.53% ~ 7.53%），其促生效应优于SA。② ABA与SA处理显著提高蓖麻根部Cd含量（增幅23.54% ~ 95.55%），但抑制Cd向地上部转运（TF降低23.22% ~ 37.26%）。③ABA1和ABA2处理均显著降低根际土壤可溶性有机碳（较CK降低24.76% ~ 25.48%），SA2处理显著提高根际土壤可溶性有机碳（较CK提高38.34%），且经过SA处理后的土壤可溶性有机质中富里酸含量显著高于CK处理。④ABA1和SA1处理能降低根际土壤Cd的离子交换态（F1-Cd），提高吸附态（F2-Cd）。ABA1和SA1处理的F1-Cd分别比CK降低9.41%和4.52%，F2-Cd分别提高24.95%和31.60%。
    结论 喷施适宜浓度的外源植物激素可改变根际Cd形态分布并调控植物Cd转运过程，提高植物修复效果，其中1 µmol L−1的ABA叶面喷施效果最佳。

     

    Abstract:
    Objective The aim was to investigate the effect and mechanism of spraying exogenous phytohormones (abscisic acid ABA and salicylic acid SA) to regulate the remediation of cadmium (Cd)-contaminated soil by the tolerant plant castor, thereby to elucidate the differences of exogenous phytohormones in regulating the migration and transformation of Cd in the soil-plant-system.
    Method The castor (Ricinus communis L.) was used as a test plant by carrying out pot experiments. Foliar sprays of salicylic acid (SA) at 0.1 mmol L−1 (SA1) and 0.8 mmol L−1 (SA2) and abscisic acid (ABA) at 1 µmol L−1 (ABA1) and 20 µmol L−1 (ABA2) were applied, respectively. The effects of exogenous phytohormones on growth, photosynthetic pigments, and Cd transport coefficients of castor bean plant, as well as the rhizosphere soil physicochemical properties and Cd fractions were investigated.
    Result ① ABA treatment significantly promoted castor growth (biomass elevated by 6.53% to 7.53% compared with CK), and its growth-promoting effect was superior to that of SA. ② ABA and SA treatments significantly increased the Cd content in castor roots (increased by 23.54% to 95.55%), but inhibited Cd translocation to the aboveground (TF decreased by 23.22% to 37.26%). ③ Both ABA1 and ABA2 treatments significantly reduced rhizosphere soil DOC (by 24.76% to 25.48% compared to CK), and SA2 treatment significantly increased rhizosphere soil DOC (by 38.34% compared to CK). The content of fuselic acid like after SA treatment was significantly higher than CK. ④ ABA1 and SA1 treatments reduced the rhizosphere soil ion-exchange state (F1-Cd) and increased the adsorption state (F2-Cd). The F1-Cd of ABA1 and SA1 treatments were reduced by 9.41% and 4.52% compared with that of CK, respectively. The F2-Cd was increased by 24.95% and 31.60%, and the low-concentration phytohormone treatments were the most significant for the enhancement of the bio-effectiveness of Cd.
    Conclusion Spraying appropriate concentrations of exogenous plant hormones could remodel the morphological distribution of rhizosphere Cd, regulate the Cd transport process in plants and strengthen the phytoremediation effect. The foliar spraying of 1 µmol L−1 ABA had the best effect.

     

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