Colloidal properties of winter wheat plants in relation to frost resistance

Abstract

1. Certain colloidal properties of winter wheat plants have been found to be closely related to frost resistance, and provide indices of hardiness which may have practical application in the breeding and selection of hardy varieties.2. The imbibition pressure of fresh leaves, in the winter-hardened condition, was found to be in most cases directly related to hardiness.3. The volume of press-juice obtained per 100 gm. of hardened leaves was inversely proportional to the hardiness of a variety. This volume is largely determined by two hardiness factors, the dry matter content and imbibition pressure of the leaves.4. When unhardened leaves were used, no relation could be found between imbibition pressure or volume of press-juice and hardiness.5. The imbibition pressure of hardened leaves appears to depend on the physical state of the cell colloids characteristic of living tissues, since this property was lost when the tissues were killed.6. The moisture content of hardened tissues tends to be inversely proportional to hardiness. There is some evidence that in hardy varieties it fluctuates less with changes in weather conditions, and a possible explanation of this as a colloidal property is suggested.7. The quantity of hydrophilic colloids contained in the press-juice, as measured by an effect on the activity of water, was found to be directly proportional to hardiness.