Nitrogen Uptake Characteristics of Corn Roots at Low N Concentration as Influenced by Plant Age
1976
Edwards, J. H. | Barber, S. A.
Information is needed on the relation between concentration of N in solution, CN, and the rate of N uptake by corn (Zea mays L.) roots in order to evaluate the soil and crop parameters affecting N fertilizer efficiency. Data on net N influx, Iₙ, vs. CN were obtained for N levels below 150 μM on corn plants of seven ages ranging from 15 to 58 days (2 weeks after tasseling). Iₙ was determined by measuring rate of N depletion from the solution in which corn plants grew. Both NH⁺₄ and NO⁻₃ forms of N were used. The experiments were conducted in the growth chamber and greenhouse. Maximum influx, Iₙ₋ₘₐₓ, occurred above 21 μM N concentration. Values of Iₙ₋ₘₐₓ, varied with plant age and were greatest with 18 to 24-day-old plants and decreased exponentially to 58-day-old plants. Iₙ ceased when the averaged CN value decreased to 4 μM. This minimum N concentration varied little with plant age. Since the range of CN values where In varied was only 4 to 21 μM, the tune period when CN is within this range for corn growing in the field is probably short so Iₙ will usually be at either Iₙ₋ₘₐₓ or 0.
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