Phosphate Uptake Rate of Corn Roots as Related to the Proportion of the Roots Exposed to Phosphate
1974
Jungk, A. | Barber, S. A.
Little information is available on the effect of reducing the proportion of a plants roots in contact with P on the rate of P uptake by those roots. Three experiments were conducted with corn (Zea mays L.) in solution culture in a growth chamber. In the first experiment trimming roots to reduce root length per plant gave results on P uptake similar to using a split-root system where a portion of the roots were in a nutrient solution containing 50 μM P. Uptake of P over an 8-hour or shorter period was in proportion to the length of root exposed to the P solution. Hence, phosphorus uptake rate per unit of root was not increased by reducing the proportion of the root in contact with P. In an experiment conducted over a 4-day period, with P levels of 100 and 1000 μM, an increase of 20 to 40% P uptake per unit of root occurred when root length was reduced to 37 to 58% by trimming. A lower P level in the plants with trimmed roots as compared to those with untrimmed roots may have caused the increase in P uptake rate per meter of root. In a 4-hour experiment with P concentrations between 5 and 10 μM, trimming the roots did not increase the P uptake rate per unit of root length. The results indicate that it is necessary to supply P to a large proportion of the roots in order to adequately supply the plant.
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