Influence of Root-zone Temperature and P Supply on Total and Inorganic P, Free Sugars, Aconitate, and Soluble Amino N in Corn1
- R. P. Patterson,
- D. L. Grunes and
- D. J. Lathwell2
Corn (Zea mays L.) plants were grown for 4 and 6 weeks in sand culture at root-zone temperatures of 15, 20, and 25 C and P levels of 2, 9, and 30 ppra P to test the hypothesis that increased P could overcome the effects of low root-zone temperature. Growth of roots, sheaths, and blades was restricted when plants were exposed to rootzone temperatures of 15 or 20 C and P levels of 2 or 9 ppm P, compared to growth at 25 C and 30 ppm P. Concentration of total P in all plant parts was as great at 15 as at 25 C. The harmful effects of low root-zone temperature were not overcome by the application of higher P rates. Concentration of inorganic P and the fraction of total P that was inorganic P were higher at the lower temperature for shoots and P-deficient roots. Free sugar levels in roots were lower at 25 than at 15 C at all P levels. Sugar levels in sheaths and blades, however, were lower at the higher temperature only under P-deficient conditions. Concentrations of aconitate and soluble amino acids were highest at 15 C, irrespective of P supply. Since metabolism of photosynthate to the level of organic and amino acids was not impeded by low root-zone temperature, it is suggested that low temperature stress was depressing growth by restricting incorporation of amino acids into protein.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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