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Agronomy Journal Abstract -

Effect of Phosphorus and Potassium on Alfalfa Root Anatomy1


This article in AJ

  1. Vol. 61 No. 5, p. 805-808
    Received: Mar 10, 1969

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  1. M. G. Schnappinger Jr.,
  2. V. A. Bandel and
  3. C. B. Kresge2



The effects of P and K on alfalfa (Medicago saliva L.) root anatomy were determined. A sand culture method was used to grow the plants. Phosphorus (P) levels in the nutrient solutions were 0, 3.4, 6.9, 13.8, 27.7, and 55.4 ppm at the beginning of the experiment. Potassium (K) was supplied at the rates of 0, 4.3, 8.6, 17.3, 34.6, 51.9, 69.3, and 173.2 ppm. No effort was made to maintain the nutrient solutions at their initial levels.

Plants were harvested three times at approximately 28-day intervals when the plants were in the full-bloom stage. The roots were preserved in a 70% Formalin-acetoalcohol fixative. Permanent microscope slides were prepared from which various characteristics of alfalfa root anatomy could be studied.

Root diameter was Increased by the addition of either P or K to the nutrient solution. Xylem vessel diameter was decreased by the removal of either P or K. But, removal of P from the nutrient solution had a greater effect on xylem vessel diameter than did K. Xylem vessel differentiation as well as the percent of the root area occupied by xylem vessels was increased more by P than by K.

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