Effect of Pre-sowing Seed Treatment on Seed Germination and Seedling Vigour in Natural Dye-yielding Species Blue Gold (Indigofera tinctoria L.)

The emerging demand of natural indigo dye due to the environmental and sociological concerns imparted by the synthetic dye helps in leveraging the conventional natural indigo dye production process in many developing countries, including India. Despite having remarkable global market potential, the high price of natural indigo dye impedes its extensive commercialization. But the seeds of the indigo species are very small and possess a hard seed coat. Therefore, in the present study, pre sowing seed treatment for indigo to assess the germination percentage in nursery level were carried out. The various pre sowing treatments viz., acid scarification, hot water, cold water and mechanical scarifier were carried out to break the dormancy of the seeds. About 1gm of seeds were subjected to either acid scarification viz., 50% conc.H2SO4, 75% conc.H2SO4 and 100% conc. H2SO4 (seeds are subjected to treated at the time various interval of Quick dip,10 min,15 min), Hot water treatment (seeds are placed in boiled water in a water bath at various temperature (60°c, 80°c and 100°c) at various time interval (6 hr, 12 hr and 24 hr) and leaving them until the water cooled, Cold water treatment (seeds are placed in cold water at various time interval viz., 24 hr, 48 hr, 72 hrs) and mechanical scarification viz., rubbing the seeds between sandpaper at various time interval 5 min,10 min and 15 min. Among the various pre sowing treatments, the best results were obtained when the seeds are subjected to Mechanical scarification. About 80% of the seeds germinated, higher dry matter production (0.07 g) depicted that the seedlings, with higher biomass in terms of shoot length (4.36 cm), root length (2.71 cm) and vigour index (566.4) when they are given a pre-sown treatment of sandpaper 15 min (T25). The results suggested that it could be possible to break dormancy and produce seedlings of Indigofera tinctoria on large scale.