Plant age, time of digging and carbohydrate content in relation to storage mortality and post storage vigor of strawberry plants.

摘要

In northern regions, strawberry nursery plants are often dug in the late autumn, stored over winter at -1.5 to -2.0℃ and shipped to growers in the early spring. Selecting an appropriate digging date is essential to the successful operation of thissystem, since plants which are dug too early in the autumn can deteriorate in storage and show poor post-storage vigour. Cultivars Kent, Veestar and Bounty were harvested at 10 weekly intervals beginning October 3, in 2 consecutive years from 3 fields inthe Annapolis Valley, Nova Scotia, Canada. In the first year (1995), first daughter plants were stored over winter at -1.5℃ and then assessed for mortality and post-storage vigour when planted in the field. In the autumn of 1996, first, second and third generation daughter plants were harvested to assess the combined effects of plant age/size and time of digging on post-storage vigour. Field measurements of crown temperature were used to calculate accumulated chilling hours ( < 8℃) for each year. Plant mortality at different digging dates varied with year and daughter position. Third generation daughter plants showed reduced survival at early dates -- but all plants dug after November 7 showed full survival. Plant vigour (number of daughters and runners) increased in all cultivars and plant ages in the later digging dates but in most cases, there was little benefit in delaying digging beyond November 20. Early dug plants had relatively low concentrations of leaf and root glucose, fructose, sucroseand raffinose, high leaf starch and low root starch concentrations. Concentrations of leaf sugars (particularly glucose and fructose) were higher in 1996 (a year with below average temperature) than in the previous year (with above average temperature),but root starch was lower. The results suggest that optimum digging dates vary little from year to year and are not closely related to seasonal temperature conditions.