不同磷水平下植物体内镉的积累、化学形态及生理特性

在控制条件下，将玉米、小麦植株在含有不同浓度磷（ｃ（Ｐ）０，０．１２，０．６，３．０ｍｍｏｌ／Ｌ）和镉（ｃ（Ｃｄ）０，４．０μｍｏｌ／Ｌ）的营养液中培养２１ｄ，研究植株体内各种镉的形态、生理特性和酶活性的变化，选择三种主要镉的形态，即氯化钠可提取态（镉与蛋白质或多肽结合态），醋酸可提取态（镉与磷酸盐的结合态）和去离子水可提取态（水溶性、有机酸盐镉的形态）作为优势态镉加以分析和研究。结果表明，提高介

ACCUMULATION, CHEMICAL FORMS AND PHYSIOLOGICAL CHARACTERIZATION OF CADMIUM IN PLANTS AFFECTED BY PHOSPHORUS

Corn and wheat cultivated in hydroponic culture solution with supplies of cadmium (c(Cd)0, 4.0 μmol/L) and phosphorus (c(P)0, 0.12, 0.6, 3.0 mmol/L) under controlled growth conditions in relation to the chemical forms of Cd, growth and physiological parameters, and enzyme activities of 21-day-old plants were investigated. The three predominant forms of Cd were NaCl-extractable Cd (related to Cd-binding proteins or polypeptides), acetic acid-extractable Cd (CdHPO4, Cd3(PO4)2, or Cd-polyphosphates), and water-extractable Cd (organic acid complexes). Increasing application of P tended to reduce the percentage of Cd combined with proteins and increase the amount of Cd-phosphates. Decreased cell plasma membrane permeability and K+ leakage of Cd-treated plants were observed with the P supply of 0.6 mmol/L. The moderate supply of P (0.6 mmol/L) also improved the contents of chlorophyll pigments, the activities of root dehydrogenase and leaf nitrate reductase in Cd-treated plants, whereas supply with an excess of P (3.0 mmol/L) showed not to be more effective in the alleviation of Cd toxic to plants. Results showed that wheat was more tolerant to Cd toxicity than corn. Fig 5, Tab 4, Ref17