硒镉伴生对富硒土壤柑橘生长及生理代谢的影响

为保障富硒柑橘的安全生产,明确富硒土壤硒镉伴生现象对柑橘生长、硒镉吸收转运和抗氧化能力的影响,采用盆栽试验,以一年生大雅柑橘为试验材料,研究添加硒代蛋氨酸(SeMet,CK,模拟富硒土壤)和添加SeMet与镉(模拟富硒土壤硒镉伴生)对富硒土壤柑橘的生长指标、硒镉含量、叶片还原型抗坏血酸-谷胱甘肽(AsA-GSH)循环效率的影响。结果表明,与CK相比,富硒土壤中,硒镉伴生增加了柑橘叶片叶绿素a+b、叶绿素a、叶绿素b和类胡萝卜素含量,但对株高、新梢长度、新梢数量以及根茎叶的干物质量影响不显著;在富硒土壤中,硒镉伴生显著增加了大雅柑橘硒含量和硒的富集系数(BCF),降低了硒的转运系数(TF);硒和镉主要分布在根系,其次是叶片和茎;在AsA-GSH循环中,硒镉伴生使过氧化氢(H₂O₂)和还原型抗坏血酸(AsA)含量显著上升,脱氢抗坏血酸(DHA)含量上升但未达到显著水平,抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)活性和脱氢抗坏血酸还原酶(DHAR)活性显著上升,而GSH和氧化型谷胱甘肽(GSSG)含量下降,AsA/(AsA+DHA)和GSH/(GSH+GSSG)比值降低,谷胱甘肽过氧化物酶(GPX)活性显著降低。本研究为阐明镉胁迫对富硒土壤柑橘的生理影响机制提供了理论依据。

Effect of Selenium Cadmium Associated on Growth and Physiological Metabolism of Citrus in Se-enriched Soil

In order to ensure the safe production of selenium (Se)-enriched citrus, effect of cadmium(Cd) associated with Se-enriched soil on citrus growth, uptake and transport of Se and Cd, and antioxidant capacity were clarified. In this study, potted old Daya were employed as the experimental material and plants in selenomethionine (SeMet) condition were as the control for the Se-enriched soil, and in the addition of Cd condition as the simulation of the association of Cd-Se in Se-enrich soil as the treatment. The growth parameters, contents of Se and Cd, and the efficiency of cycle of ascorbic acid (AsA)-glutathione (GSH) in leaves were measured. The results showed that in the Se-enriched soil, the content of chlorophyll a+b, a, b and carotenoid in citrus leaves was increased by Cd-Se associated treatment, but no significant effects were found on plant height, length of new shoots, number of new shoots and dry matters of root, leaves and stems. In Se-enriched soil, Se-Cd associated treatment significantly increased the content of Se and the biological concentration factor (BCF) of Se, but decreased the translocation factor (TF) of Se. In addition, Se and Cd were mainly distributed in roots, followed by leaves and stems. In AsA-GSH cycle, hydrogen peroxide content was increased by Se-Cd associated treatment, and the contents of AsA and oxidation of ascorbic acid (DHA) were also increased. Meanwhile, the enzyme activities of ascorbic acid peroxidase (APX), the activity of glutathione peroxidase (GR) and dehydrogenation of ascorbic acid reductase (DHAR) were increased. The levels of GSH and oxidized glutathione (GSSG) and the activity of glutathione peroxidase (GPX) were reduced. The ratios of AsA/(AsA+DHA) and GSH/(GSSG+GSH) were not significantly reduced by Cd-Se associated treatment. This study provides theoretical basis for elucidating the physiological influence mechanism of Cd stress on Se-enriched soil.