Germinability of sorghum and soybean seed exposed to low temperatures

1. Sorghum seeds were germinable when their moisture content was between 50 and 60%. Soybean seeds with a moisture content of 66.9% were germinable. 2. Freshly harvested, immature seeds of sorghum were dormant. Dormancy was overcome by curing, by prechilling, and by continuing the test at 20 degrees to 30 degrees C until all viable seeds had germinated. Immature seeds of Peking soybeans from one collection were dormant and required 41 days for all of the viable seed to germinate at 30 degrees C. 3. The viability of immature sorghum seed was affected by the method of curing the seeds. Seed allowed to cure by hanging the panicles in the laboratory germinated better than that which was threshed and cured in cloth sacks. 4. Mature sorghum seed with a moisture content of 15% or less was unaffected in viability by exposure to any temperature between 33 degrees and -20 degrees F. 5. Immature seed of sorghum and soybeans was reduced in viability by exposure to low temperatures. The reduction in vitality at a certain moisture content increased as the temperature decreased. As the moisture content decreased the reduction in viability from exposure to any certain temperature decreased also. 6. Sorghum seed in small lots with a moisture content of 16 to 19% was not seriously injured by exposure for 10 hours to a temperature of -20 degrees F. Exposure for 10 hours at -20 degrees F caused serious injury when the moisture content of the seed was 22% or more. 7. Soybean seed in small lots with a moisture content of 30 to 32% or less was not reduced in viability by freezing for 10 hours at -20 degrees F. At 20 degrees F no injury occurred to seed of most varieties with a moisture content of 50 to 60%. Soybean seed may contain a much higher percentage of moisture than sorghum seed without being injured by exposure to freezing temperatures. 8. When immature sorghum seed is harvested for seed purposes high viability may be maintained by curing the seed in the panicles.