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This article in AJ

  1. Vol. 65 No. 6, p. 972-975
     
    Received: June 1, 1973


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doi:10.2134/agronj1973.00021962006500060038x

Influence of Potassium Nutrition on Net CO2 Uptake and Growth in Maize (Zea mays L.)1

  1. G. O. Estes,
  2. D. W. Koch and
  3. T. F. Bruetsch2

Abstract

Abstract

A heavy dependence on K fertilization in the northeastern U. S. coupled with the luxury accumulation of this element in plants suggest a need for further research. The objective of this greenhouse experiment was to relate CO2 uptake, determined by a radioactive carbon method, and yield of maize (Zea mays L., var. Wisconsin 335A') with K concentration and content of tissue. Plants were grown at substrate levels of K from O to 9 mM/liter of K in hydroponic culture.

A significant correlation existed between both concentration and content of K and dry weight of plants. There was a curvilinear relationship between both leaf (youngest fully expanded) and plant K percentage and net CO2 uptake. Leaf content of K between 0.75 and 1.0% was considered critical (42-day-old maize) because CO2 fixation was seriously reduced at lower concentrations. There was a close agreement between CO2 assimilation and dry weight over the range in substrate K concentrations, .50 to 9.0 mM/liter. An increase in dry weight at the K level of 0.25 mM/liter was not accompanied by an increase in CO2 fixation. Uptake of CO2 increased nearly 60% between K concentrations of 0.25 and 0.50 mM/liter but at a much slower rate between 0.50 and 9.0 mM/liter.

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