AVOIDING SUPERCOOLING OF ROOTS DURING LABORATORY FREEZING STUDIES

Abstract

Supercooling during laboratory freezing may prevent determination of the freezing temperatures that injure roots. Several freezing procedures were tried to prevent supercooling. Forsythia root sections partially imbedded in ice did not supercool, but sections frozen in air in moist greenhouse soil, or wrapped in moist tissue paper supercooled to −2 to −6 °C before freezing. Rate of the temperature drop and use of cold-hardened and nonhardened roots did not affect occurrence of supercooling.