OSMOCONDITIONING OF TOMATO AND ONION SEEDS

Seeds of tomato and onion were osmoconditioned for periods of 1 to 4 weeks in polyethylene glycol, molecular weight about 8000 (PEG-8000), solutions at water potentials between -5.8 and -14.9 bars. Subsequently the seeds were germinated at 10, 18 and 26°C. Most of the treatments led to a rapid germination response and this enhancement was greater at cooler temperatures. Minimum 7-days osmotreatments of tomato and onion seeds at -8.6 and -11.9 bars, respectively, produced rapid germination responses at 15°C. Osmoconditioning of tomato seeds, followed by a moist osmoticum storage at 5 ± 1°C, resulted in reduced germination and seedling emergence, but with onions the enhanced germination and emergence response of the osmoconditioned seeds remained unaffected. Field testing of osmoconditioned seeds of several tomato cultivars at two sites in Ontario showed enhanced seedling emergence, plant development and more breaker-red tomato fruits at harvest, indicating earlier maturity. However, no total yield differences between the osmoconditioned and non-osmoconditioned plants were observed. © 1990.