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This article in CS

  1. Vol. 30 No. 1, p. 123-128
    Received: Oct 28, 1988

    * Corresponding author(s):
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Phosphorus Enhancement of Salt Tolerance of Tomato

  1. A. S. Awad ,
  2. D. G. Edwards and
  3. L. C. Campbell
  1. B iological and Chemical Res. Inst. (BCRI), PMB 10, Rydalmere, 2116, New South Wales, Australia
    D ep. of Agriculture, Univ. of Queensland, St. Lucia, 4067, Australia
    D ep. of Agronomy, Univ. of Sydney, Sydney, 2006, Australia



Increasing plant P supply has been shown to either increase or decrease the salt tolerance of many plants. Tomato plants (Lycopersicon esculentum Mill.) were grown in a greenhouse in a continuously flowing solution culture system to investigate whether P fertilization modified the detrimental effects of NaCl at low constant P concentrations similar to those in soil solutions. Increasing P fertilization enhanced the tolerance of tomato plants to NaCl. At 0.1, 1.0, and 10 mM P, the NaCl concentrations that reduced yields of fruit by 50% were 58,72, and 130 mM, respectively. Salinity reduced foliar P concentrations. This may have been mediated partly through ionic strength effects, which decreased the activity of H2PO4−1 by about 40%. Plants grown under saline conditions had higher internal P requirements. When the NaCl concentration was increased from 10 to 50 and 100 mM, the corresponding concentrations of P in the youngest mature leaf required to obtain 50% yield were increased from 1.8 to 2.4 and 3.0 g kg−1. The change in internal P requirement was also evident by the relative severity of foliar symptoms of P deficiency in plants growing in the saline treatments at any given foliar P concentration. Adequate P nutrition was essential for effective ionic compartmentation. Under saline conditions, increasing the solution P concentration from 1.0 to 10 μM decreased Na and increased K concentrations in immature leaves but increased Na and decreased K in the mature leaves. Accumulation of ions for osmotic adjustment and restriction of Na and Cl accumulation in immature leaves appear to be involved in P enhancement of salt tolerance of tomato plants.

Joint publication of the BCRI and the Universities of Sydney and Queensland.

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Copyright © 1990. Crop Science Society of America, Inc.Copyright © 1990 by the Crop Science Society of America, Inc.