Effect of Water Stress on Turgor Differences and C-Assimilate Movement in Phloem of Ecballium elaterium.
The effects of water stress on pressure differences and (14)C-assimilate translocation in sieve tubes of squirting cucumber Ecballium elaterium A. Rich were studied. Water stress was induced by transfer of plants from culture solution to a polyethylene glycol 6,000 solution having an osmotic potential of -18.2 atm. Sieve tube turgor, turgor differences between source and sink, and translocation rate were decreased. After 260 minutes of translocation, only 19% of the total fixed (14)CO(2) had moved out of the leaf, compared to the control value of 62% after the same period of time. The results suggest that water stress slows translocation by lowering sieve tube turgor differences, which are essential for the pressure flow mechanism of conduction.
Sheikholeslam
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Department of Botany, University of California, Davis, California 95616.
Currier
H B
HB