A kinetic study of phosphorus absorption by excised maize roots from flowing solutions influenced by 2,4 dinitrophenol and viscosity of solution

Abstract

The effect of 2,4 dinitrophenol and increased viscosity of the absorption solution on the absorption of phosphorus by excised roots of maize plants was investigated. The concentration of the solution was 0.1 mM KH₂PO₄, the activity of³²P was 52 µCi l^-1. The temperature of the absorption solution was 26 °C, pH 5.5, aeration prior to the experiment. There was 11 of solution for every 1 g of roots. Two basic variants were used for comparison: with non-flowing solution and with solution flow (circulation) of 0.162 cm s^-1, respectively. In all cases, 2,4 dinitrophenol reduced the rate of phosphorus absorption by the roots regardless of the mechanism of phosphorus supply to the roots (diffusion, mass flow). If it is proved that 2,4 dinitrophenol inhibits the active uptake of phosphorus, then the uptake of phosphorus by the roots increased under the influence of mass flow will be active,i.e., connected with energy metabolism.

Raising the viscosity of the absorption solution 3.3 times over that of water by means of potato starch substantially reduced the absorption of the phosphorus transported to the absorption zone by diffusion and practically did not affect the rate of absorption, or the amount of anions transported to the absorption area by mass flow.