Effect of Environmental Stress on the Growth and Amounts and Forms of Phosphorus in Plants1
- A. N. Sharpley and
- 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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