Tomato seeds were more responsive than wheat or lettuce seeds to the presence of an inhibitor in the juice of tomato fruits. Seed germination and seedling growth decreased with increasing concentrations of juice. Inhibition of seed germination in 20% juice with an osmotic concentration of less than 0.1 M was significantly less than in 0.1 M glucose or mannitol with 0.01 M citric acid at pH 4.4. The inhibitor in tomato juice was thermostable, but the effect decreased with prolonged storage at -20°C. There were cultivar differences in the amount of inhibitor present in ripe tomato fruits.
Received for publication September 21, 1970. Taken in part from a thesis submitted by the senior author in partial fulfillment of the requirements for a Master of Science degree in the Department of Vegetable Crops, University of California, Davis.
Present address: Department of Horticulture, National Taiwan University, Taipei, Taiwan.
Department of Vegetable Crops, University of California, Davis.
The authors wish to thank Mrs. Mitzi Aguirre for technical assistance and K. N. Paulson for use of his computer programs.