Seed Viability Determinations in Cabbage Utilizing Sinapine Leakage and Electrical Conductivity Measurements

A need exists for the development of rapid seed quality teststhat determine viability (defined as the ability to germinate)without the necessity for completion of germination. In cabbage(Brassica oleracea var. capitata L.) the compound sinapine,a choline ester of sinapic acid, has been shown to leak fromheat-killed (HK.) but not from viable seeds. Sinapine leakagewas studied as a more accurate method for identifying viableseeds than the conductivity test. After an 8 h soak, a 26-folddifference in sinapine leakage was detected between HK and viableseeds (as measured by the absorbance at 388 nm at pH 12) comparedto a 4-fold difference measured by electrolyte leakage. Theremainder of the studies were conducted on two seedlots of thesame cultivar. Viability was predicted on the same seed by assessingleakage from individual seeds into the soak water using threemethods; soak water colour, absorbance at 388 nm, and electricalconductivity. This information was compared with the actualgermination of each seed for the two seedlots. For both seedlots,the presence of sinapine in seed soak water (detected eitherby a yellow solution colour at high pH or by high absorbance),identified more seeds that were non-viable than the partitioncoefficient calculated from conductivity measurements (76%,72% and 28% of non-viable seeds were identified, respectively).It is proposed that leakage of sinapine is a better predictorof cabbage seed viability than electrical conductivity. Key words: Seed deterioration, seed leakage, germination prediction