Solute Leakage fromSolanum nigrumL. Seeds Exposed to High Temperatures during Imbibition

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Abstract
Exposure of Solanum nigrum L. seeds to high temperatures during imbibition affected their leakage pattern: (1) The rate of leakage of total electrolytes was markedly increased with elevation of temperature. The increase was highest during the first 3 h of imbibition but with a reduced rate thereafter. (2) Leakage of Na+ was almost complete after 6 h of imbibition at both temperatures, but much more Na+ leaked out at 50°C than at 25°C. (3) A marked increase in leakage of K+ occurred after 24 h of exposure to 50°C so that after 96 h three times more K+ leaked out at 50°C than at 25°C. (4) After 6 h of imbibition Ca11 and Mg++ continued to leak out at 25°C and at 50°C at a similar rate. (5) Imbibition at an elevated temperature induced a marked increase in the leakage of both nucleic acids and proteins. (6) Malate dehydrogenase was not detected in the leachate at 25°C, but was found after 48 h at 50°C. It is assumed that this enzyme was of cytoplasmic origin, indicating heat damage to membranes. The possible role of the above phenomena in the loss of viability of the seeds due to exposure to high temperature during imbibition is discussed.