Variation in Germination and Amino Acid Leakage of Seeds with Temperature Related to Membrane Phase Change

Leakages of amino acids and/or fluorescent material as functions of temperature between 15 and 40 C are reported for imbibed seeds of Avena fatua L., Lactuca sativa L., Barbarea vulgaris R. Br., Amaranthus albus L., Abutilon theophrasti Medic., Lychnis alba Mill., Daucus carota L., Setaria faberi Herrm., Setaria viridis (L.) Beauv., and Datura stramonium L. The leakage indicates prominent increase in permeability of the plasmalemma in the 30 to 35 C range for 8 of the 10 kinds of seeds studied. Germination of the seeds at constant temperatures or with daily shifts in temperature is related to the membrane transition temperature for permeation by amino acids. Seeds of A. albus and A. theophrasti, which did not show membrane changes in the 25 to 40 C range, germinated best at 35 to 40 C; the other seeds germinated best below 30 C. Seeds of B. vulgaris showed rapid permeation of limiting membranes upon initial wetting with water, which was indicative of membrane disorder when dry. Leakage under anaerobiosis was observed for S. faberi seeds.