The effects of natural and synthetic seed preconditioning agents (SPAs) in hastening seedling emergence and enhancing yield and quality of processing carrots

Field trials were conducted for two consecutive field seasons (2001 and 2002) to study the effects of various natural and synthetic seed preconditioning agents (SPAs) on seedling emergence as well as yield and recovery of carrots (Daucus carota var. Sativus L.). Carrot seeds were preconditioned by soaking seeds in aqueous solutions containing various SPAs viz., Ambiol 0.1 mg L−1, glycinebetaine 100 mg L−1 (GB), BIOPROTECT 2 (BP2). Fields were located in Centreville (2001) and Medford (2002), King's County, Nova Scotia. Measurements were made on seedling emergence, soil moisture, soil temperature, final yield and recovery of various grades. Seed preconditioning using BP2 and GB during 2001 and BP2 and Ambiol during 2002 enhanced seedling emergence significantly and differentially in slicer and dicer varieties. Yield and recovery of fancy grade roots of Oranza increased nearly 71 and 146% respectively, compared to the untreated control during 2001 due to preconditioning using BP2. In a commercial scale field trial conducted in 2002, preconditioning with Ambiol (0.1 mg L−1) or GB (100 mg L−1) significantly enhanced emergence of dicer carrots by nearly four and three folds, respectively, over the untreated control. Final yield and quality however, was not increased by any of the SPAs in both slicer and dicer carrots in 2002. Preconditioning seeds using water was also equally effective as to that of SPAs in achieving early and high emergence suggesting the possibly of a natural SPA from carrot seeds. A significant enhancement in yield and root recovery due to BP2 preconditioning may perhaps be due to its enhanced sink activity facilitating root bulking together with its antistress, antioxidant properties protecting young seedlings from soil moisture deficits.