Pénétration et migration du 59Fe appliqué sur les feuilles de Maïs; effet du dimáthylsulfoxyde

The uptake and translocation of ⁵⁹Fe applied to leaves of Zea mays L. is studied with special reference to the effect of dimethylsulfoxide (DMSO). ⁵⁹Fe is deposited on corn leaves as droplets of solution of ferrous sulfate or ferric nitrate (1 mM. The uptake of ⁵⁹Fe is affected by the associated anion; the penetration is more important with the nitrate than with the sulfate. The translocation of ⁵⁹Fe from the treated part during 24 hours is very low in all the experiments. The exsorption of ⁵⁹Fe taken up, from the site of application in different solutions (FeSO⁴, 7H₂O; EDTA Na) concerns only a low percentage of ⁵⁹Fe present in the treated part. DMSO (0.5 and 1 %) increases the uptake but not the translocation of ⁵⁹Fe applied as sulfate; it seems to have no effect when iron is applied as nitrate. The increase during 24 hours reaches between 32 % and 53 % in seven experiments with sulfate. The effect also appears in an experiment conducted during four weeks, with several applications of ferrous sulfate during this time. This effect of DMSO is discussed: it is mainly explained by the great hygroscopicity of this solvent, therefore the effect would in part depend on the solubility of salts in concentrated DMSO and of the climatic conditions: relative humidity and temperature of the air.