Influence of physiological condition at the time of lifting on the cold storage tolerance and field performance of ash and sycamore

Abstract

The physiological condition of ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.) seedlings sampled from the same nursery in Ireland was evaluated at periodic intervals from September to May, and after cold (1°C) storage from the time of lifting until May, in 1997/98. Shoot water potential (WP), root electrolyte leakage (REL) and root growth potential (RGP) were assessed. In addition, the survival and height increment of seedlings established in a field trial in tandem with the physiology work was determined after one growing season. Shoot WP of freshly lifted ash seedlings, but not sycamore, decreased to low values in the winter. REL and RGP values were generally also lower in ash than in sycamore on most lift dates. Furthermore, sycamore became more highly active earlier in the year (February/March) than ash (April/May). The effect of cold storage on physiological responses was not consistent. The survival of seedlings in the field was close to 100 per cent regardless of treatment. The height increment of freshly lifted sycamore was best for stock planted from September to early March, whereas ash grew best when planted early (October-November) or late (after February) in the lifting season, although differences between most lift dates were small in ash. Under operational forestry conditions, planting during some of these periods may not be advisable due to the potential effect of handling damage. Cold-stored ash planted in May after cold storage performed well for seedlings lifted to the store from December to February, but the physiologically more active sycamore performed best when stored from February.