Germination of Italian ryegrass and sorghum were measured at a range of temperatures and with PEG treatment at several different levels of concentration and treatment period to evaluate the effects of osmoconditioning with polyethylene glycol(PEG-8000). The results obtained are summarized as follows: 1. Cumulative germination percentage of intact Italian ryegrass seeds did not show much difference among temperatures, while that of sorghum seeds decreased markedly at low temperature. 2. Italian ryegrass seeds osmoconditioned with 20% PEG solution for two days at 10^{circ}C.$ accelerated germination at 10^{circ}C.$, with injurious effect of osmoconditioning at higher temperature for many days. 3. Osmoconditioning with 20% PEG solution for two or four days at 10^{circ}C.$ increased germination of sorghum seeds, while the seeds treated at higher temperatures for long period suppressed germination.