VIGOR RATING OF WHEAT SEED

The seed vigour of wheat (Triticum aestivum L. cultivar 'Sonalika') of different vigour levels obtained by ageing or hydration-dehydration treatments, was tested by their comparative germinability, bioassay of gaseous emanations employing high-vigour jute (Corchorus olitorius L. cultivar 'JRO 632') seeds and chemical assay of volatile aldehydes in the gaseous emanations using the aldehyde trapping reagent 3-methyl-2-benzothiazolinone hydrazone (MBTH, 0.2% solution). The vigour of the stock seeds was positively correlated with seedling length but negatively correlated with the coefficient of variation (standard deviation of seedling length expressed as a percentage of the mean). The growth of jute seedlings (bioassay material) exposed to the gaseous emanations of germinating high-vigour wheat seeds was higher than with corresponding medium and low-vigour seeds. Hydration-dehydration treatments of stock seeds, such as dipping-drying, soaking-drying and moisture equilibration-drying, showed greater post-ageing germinability, coupled with greater seedling growth of jute grown along with wheat, demonstrating high positive correlations between the stock seed vigour and bioassay results. Significant negative correlations were obtained between wheat seed vigour and volatile aldehyde production. The results have been discussed in terms of lipid peroxidation and volatile aldehyde production in the stock seeds vis-a-vis inhibition of seedling growth of the bioassay material.