Relative contributions of soil chemistry, plant physiology and rhizosphere induced changes in speciation on Ni accumulation in plant shoots

• Published in: Plant and soil 2003-08, Vol.255 (2), p.619-629
• Main Authors: Pinel, F, Leclerc-Cessac, E, Staunton, S
• Format: Article
• Language: English
• Subjects: Acid soils; Acidic soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; bioaccumulation; Biological and medical sciences; Brassica napus; clay soils; Festuca ovina; Festuca rubra; Forest soils; Fundamental and applied biological sciences. Psychology; Life Sciences; Lolium perenne; Nickel; Nutrient solutions; nutrient transport; nutrient uptake; plant growth; Plant physiology; Plant roots; Plant species; Plants; quantitative analysis; Radioactive tracers; Raphanus sativus; Rhizosphere; Roots; sandy soils; Shoots; silty soils; soil chemical properties; Soil chemistry; Soil nutrients; Soil pH; Soil pollution; Soil properties; Soil solution; Soils; Solanum lycopersicum var. lycopersicum; Speciation; Trace elements; Trifolium alexandricum; Vegetal Biology
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1026052228609

The aim of this study is to rank the relative importance of soil properties, root uptake and root-to-shoot redistribution on the transfer of the trace element nickel from soil to the shoots of non hyperaccumulatings plants. Two contrasting soils and seven plant species have been studied using the radioactive isotope, 63Ni. Shoots and roots were analysed separately and the specific activity of each plant has been measured. The isotopic exchange properties of rhizosphere soil where compared with control non rhizosphere soil. Possible changes in Ni speciation in the rhizosphere have been assessed by comparing the isotopic exchange properties of the rhizosphere and control soil and by comparing the specific activities of Ni in each plant. The capacity of soil to immobilise added radiotracer largely determines root uptake, leading to between a 4- and 40-fold difference between soils for a given species. The redistribution of nickel from roots to shoots was fairly constant for plants grown on the rendzina, but varied strongly between species for the acid soil. This variation enhanced the contrast between species of the soil-toshoot transfer factor. Root action significantly enhanced immobilisation of added nickel in an acid soil due to the modification of speciation of initially non exchangeable soil nickel, but had little effect on a neutral rendzina. Changes in rhizosphere pH were similar on the two soils. In the acid soil, these pH changes were accompanied by changes in Ni speciation but a causative link has not been established. In the neutral soil pH changes may have modified root uptake properties.