Studies on frost injury to wheat. II. Ice formation within the plant

Abstract

The formation of ice crystals within leaves, stems, and ears of wheat plants (Triticum aestivum L.) was studied at temperatures of –3.0 to –5.0°C.

The mean velocity of propagation of the ice front in leaves at –3°C was 120 ± 4.1 cm/min. In other plant parts it was slower and more variable. Values recorded for stem internodes ranged from 76 to 0.02 cm/min and for reproductive organs from 1.0 to 0.04 cm/min. Some stem and rachis nodes (in winter-grown plants only) arrested the spread of ice crystals for several hours. This appeared to be an important mechanism for protecting young ears from frost, as they remained super-cooled for long periods if inoculation from external sources was prevented.