Uptake and translocation of root-fed32P in response to foliar and root applications of CCC and phosfon inPisum sativum

The uptake and translocation of³²P applied to nutrient solutions, as influenced by (2-chloroethyl) trimethylammonium chloride (CCC) and 2, 4-dichlorobenzyltributylphosphonium chloride (Phosfon), were investigated in growth chambers. Specific effects depended on the “Retardin”, the method of application, and the concentration. Foliar applications of CCC had no significant effect on³²P uptake 5 h after feeding. At 20 and 80h after feeding, CCC at 100 and at 1 000 mg l^?1 decreased P uptake. With root applications of CCC the same concentrations decreased P uptake as early as 5h after feeding, while the 1 mg l^?1 concentration enhanced P uptake by 40% after 20h. Both the foliar and the root applications of Phosfon influenced P uptake 5h after feeding. With foliar applications the low Phosfon concentration of 0.01 mg l^?1 increased P uptake throughout the experimental period of 80h, but the magnitudes of enhancement declined from 109% at 5h to 63% at 80h. Similarly, the enhancement of P uptake due to the 0.1 mg l^?1 foliar treatment declined from 132% at 5h to 80% at 80h. 100 mg l^?1 CCC enhanced P translocation to the shoot in 5h, with magnitudes of 29% (foliar application) and 64% (root application). At 20 and 80h the stimulations were nullified. The highest concentrations (100 mg l^?1 CCC; 10 mg l^?1 Phosfon) enhanced P translocation 80h after feeding. There were thus general enhancements of P uptake at low concentrations and suppressions at high concentrations, but these effects diminished with time, indicating transitory influences.