Sugar-beet seed steep treatments to improve germination under cold, wet conditions

Modifying the present commercial sugar-beet steep treatment (12h in 0.2% thiram suspension, 25°C) to include an initial 2h steep in 0.3M hydrochloric acid, decreased fruit weight and cortex density and improved the performance of the inherently slower part of the population under cold, wet conditions. Adding gibberellins (GA4/7) or an N-substituted phthalimide (AC 94377) to the thiram steep was also beneficial whereas kinetin of N6-benzyladenine gave no improvement. Germination was even more rapid and better synchronised following a 4-day seed advancement sequence, particularly when this started with the acid steep. Overall, it was possible to increase the proportion of seeds which gave a root or produced hypocotyls at least 2cm tall by 9% and 14% respectively; the thermal time needed for the 90th seed to germinate was reduced from 73 to 30 day degrees and synchrony could be improved at least two-fold.