An advancing and devernalizing treatment for sugarbeet seed has been developed which, in England, allows sowing to be brought forward safely by c. 10 days to around 10 March. Experiments done each year from 1988 to 1991 were used to assess the value of this change. They showed that sugar yield increased by 0-048 t/ha/day because seed advancement resulted in more rapid emergence, and by 0042 t/ha/day as a result of earlier sowing. As an average of all appropriate data from experiments in England since the 1950s, the advantage of sowing in March is 0035 t/ha/day. However, the actual change in sowing date which the farmer might achieve will depend on soil type and rainfall. Daily rainfall and evaporation data for eastern England in March and April were used to predict the number and distribution of available machinery work days. On this basis, the average sowing date was predicted to advance by 9 days. Thus the sugar yield improvement which could be produced by advancing and devernalizing beet seed is equivalent to 9 days at 0035 t/ha/day, plus 0-19 t/ha, or c. 0-5 t/ha. In practice, this should translate into an increase of 0-35 t/ha, or c. 5 % of the average yield.

Modifying the present commercial sugar-beet steep treatment (12 h in 0 .2% thiram suspension, 25 °C) to include an initial 2 h steep in 0 .3 M 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 .

Steeping sugar-beet seeds in an aqueous thiram suspension, as now used commercially in the UK, makes seedling emergence more rapid and increases the number of plants established. This study investigated whether the potassium and nitrate, removed by steeping, were needed to stimulate subsequent hypocotyl growth. Experiments under controlled conditions showed that re-incorporation of KNO, by adding the salt to the steeping solution or, less wastefully during pelleting, slightly slowed root protrusion but made hypocotyl extension more rapid, particularly under dry conditions. There were indications that placement of KNO, under the seed would be better. Nevertheless, in the field where recommended amounts of fertiliser were applied, incorporation of about 5 g KNO,/kg seed during pelleting was consistently beneficial following the four sowings. This amount decreased the time to half-final emergence by 0.3 days, gave 3% more established plants and, with the later sowings, increased dry weight in mid-May by 10%.

SummaryWith variation in rainfall patterns, evaporation, seedbed soil structure and depth of sowing, sugar‐beet seed and seedlings can be subjected to damaging extremes of water availability. Under controlled conditions, seed given progressively longer pre‐sowing treatments (steeped for 12 h at 25°C or advanced for 4 days at 25°C) was more tolerant of non‐optimal conditions than seed given a brief steep (20 min at 15°C). The prolonged steep treatment accelerated emergence and increased establishment (3% on average) in the field, compared with the brief steep. Advanced seed consistently gave the quickest emergence, produced as many plants as the prolonged steep, and was less affected by depth of sowing so its introduction should improve the establishment phase of the sugar‐beet crop.

This study confirmed that steeping sugar-beet seed in 0 .3 M hydrochloric acid for 2 h as the first part of a 12 h treatment, substantially improved performance under cold, wet conditions . Smaller benefits were also found in warmer, drier tests ; no detrimental effects were found . Adding excess sodium hydroxide at the end of the acid steep further improved the growth of the inherently slower part of the population under cold, wet conditions . Steeping seed in acid or acid followed by alkali also controlled Phoma betae as effectively as the current commercial thiram steep treatment .