[Fluxes, accumulation and transport of Cl(-) in excised corn roots].

Fluxes, accumulation and transport rates of Cl(-) in excised corn roots were investigated.Flux equilibrium in 5×10(-4)M KCl was not reached within an experimental period of 28 hr.Transport of Cl(-) (5×10(-4)M KCl) through the xylem of 4-6 cm long excised corn roots had a lag of 1-2 hr. From 6 to 28 hr rates of accumulation and transport were nearly constant (5×10(-4)M KCl). The velocity of volume-flow within the xylem was 1.5-2 cm hr(-1) (5×10(-4)M KCl). (36)Cl(-)-efflux through the cut end of roots preloaded in K(36)Cl of low concentration exhibits a discontinuity which is explained by addition of two fluxes: efflux of ions concentrated in the xylem (and symplasm) plus efflux from the vacuoles through the xylem.Accumulation of Cl(-) by excised roots approaches a maximum level (Jackson and Edwards, 1966). Influx rates remain constant while efflux rates increase with time. It is shown in this paper that the flux of Cl(-) through the xylem becomes a large proportion of the influx across the plasmalemma. Flux rates suggest that more than 50% of the Cl(-) ions transported to the xylem passed through a vacuole (5×10(-4)M KCl; 20-28 hr).