Assessing chilling tolerance in roses using chlorophyll fluorescence

Chlorophyll fluorescence (CF) was evaluated as a technique to assess chilli ng injury of rose (Rosa sp.) leaves exposed to low temperatures. In the mor e susceptible genotypes, variable fluorescence (Fv) decreased dramatically as the temperature was lowered. In the less susceptible genotypes, Fv was m ore stable and decreased more slowly as temperature fell. Our results sugge st that measurement of CF may provide a rapid method to prescreen genotypes for chilling susceptibility, as required in plant breeding.