Phosphorus supply affects zinc uptake in wheat plant.

The effect of phosphorus (P) supply on net uptake and unidirectional zinc (Zn) fluxes was studied in 21 day old wheat plants (Triticum aestivum L.) grown in nutrient solution. The supply both P and Zn were in the range in which did not limit plant growth. The higher the level of P supply the higher both net Zn uptake and net Zn translocation to the shoot. The enhanced net uptake of Zn at 5 mol m^-3 P relative to that measured at 0.05 mol m^-3 P, was due to a higher Zn-influx added to a lower ratio between the efflux and influx of Zn. Thus, our results showed that the level of P supply modulats the long term regulation of both unidirectional Zn-fluxes. The short term response of Zn-influx when changing the external level of P supply from 5to 0.05 mol. m^-3, and vice versa, is consistent with the idea that an endogenous effect of P is involved in such a regulation. The possibility is discussed of P-concentration in root cytoplasm modulating Zn-influx in plants with supraoptimum P and Zn supplies.