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Agronomy Journal Abstract -

Effect of Environmental Stress on the Growth and Amounts and Forms of Phosphorus in Plants1


This article in AJ

  1. Vol. 74 No. 1, p. 19-22
    Received: Jan 13, 1981

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  1. A. N. Sharpley and
  2. L. W. Reed2



The effects of applied fertilizer P and soil-water stress on the growth and amounts and forms of plant P were investigated to provide further information on the potential of plant material to contribute P to runoff. Cotton [Gossypium hirsutum (L.)], little bluestem (Andropogon scorparius Michx.), sorghum [sorghum sudanense (Piper) Stapf.], and soybean [Glycine max (L.) Merr.], plants were grown in the field on Durant loam, a member of the fine, montmorillonitic, thermic Vertic Argiustolls. Fertilizer P additions of 0, 50, 100, and 200 kg/ha were made and a water-stress treatment initiated by applying only one-third the amount of water lost as evapotranspiration. Plant growth and P content were determined at weekly intervals following plant emergence. Growth and total P content increased with an increase in applied fertilizer P for all plants except little bluestem. The total P and inorganic P content of the plants decreased gradually with growth. Inorganic P constituted the major proportion of plant P (approximately 80, 70, 70, and 80% for cotton, little bluestem, sorghum, and soybean, respectively), and remained constant during plant growth. A three-fold reduction in soil-water content (60-fold increase in soil-water suction) resulted in a decrease in plant growth and total and inorganic P content. The effect of the soil-water stress was reduced by increases in applied fertilizer P. It was calculated, however, that the addition of fertilizer P was not a viable economic method of increasing crop yields to negate any drop in yield due to drought conditions.

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