Some Effects of Low Temperatures on Seeds

Abstract

1. Freezing cotton seeds in liquid air inures the cotyledons so that they become cracked and split and are not able to emerge completely from the seed-coat. The secondary or true leaves do not appear to be injured by treating the seeds with liquid air. 2. When flax seeds of certain strains are treated with liquid air, a large proportion of the plants form double stems and hypocotyls; none of the plants from untreated seeds do this. Other strains rarely if ever produce plants with double stems or hypocotyls when the seeds are cooled in liquid air. 3. The time between freezing the seeds and planting them has little effect on the formation of abnormalities. 4. Increasing the moisture content of the seeds before freezing them reduces the number of plants having abnormal stems and hypocotyls. 5. Freezing the seeds in a CO2 snow-ether mixture (-80⚬ C.) is somewhat more effective in producing abnormalities than freezing them in liquid air (-190⚬ C.). As with the liquid air, no abnormalities are produced when seeds having about 10-15 per cent moisture are frozen in CO2 snow. 6. Breeding tests showed that the abnormalities produced are not inherited. 7. The mechanism by which the abnormalities are produced cannot be deduced from the data available, but it seems probable but freezing causes some physicochemical change in the protoplasm of the embryo cells which causes them to react differently to the normal stimuli; or it changes some of the restraining and formative forces, which cause the plant to develop in a more or less fixed way.