A Combined Field/Laboratory Method for Assessment of Frost Tolerance with Freezing Tests and Chlorophyll Fluorescence

Recent progress in genotyping allows for studies of the molecular genetic basis of cold resistance in cereals. However, as in many other fields of molecular genetic analysis, phenotyping for high numbers of genotypes is still a major bottleneck. The use of chlorophyll fluorescence measurements as an indicator for freezing stress is a well established and rapid method for evaluation of frost tolerance. In order to extend the applicability of this technique beyond plants grown under controlled conditions in growth chambers and sacrificed for the test, here we study its applicability for leaves harvested from field trials during winter and subjected to freezing tests. Such an approach allows for simultaneous studies of the advancement of cold hardening and other components of winter survival apart from frost tolerance. It is shown that cutting or senescence of cut leaves does not have adverse effects on the outcome of subsequent freezing stress tests. The time requirements for field sampling and laboratory testing on high numbers of genotypes allow for the application of the proposed approach for genotyping/phenotyping studies.