STUDIES FOR ASSESSING THE INFLUENCE OF HARDENING ON COLD TOLERANCE OFBARLEY GENOTYPES

Frost tolerance of 30 barley (Hordeum vulgare L.) cultivars have been field evaluated in North Italy during the 1990/1991 winter season that was characterized by exceptionally low temperatures without snow cove r. The results showed a significant correlation between cold injury an d grain yield loss (r = 0.61*). Five cultivars chosen for their varyi ng degree of frost tolerance were further evaluated using laboratory t ests. Measurements of survival rate and membrane damage were used to a ssess the influence of hardening on frost resistance. The reliability of the tests is shown by the high correlation to the field data. For b oth the laboratory temperature regimes and field conditions, the teste d cultivars showed the same order of classification. The effect of a r ise in temperature at the end of the hardening treatment on frost tole rance is also reported. The laboratory tests here proposed can be inte grated in a breeding programme for improving frost tolerance in barley .