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This article in AJ

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

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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



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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