THE INFLUENCE OF CARBOHYDRATES, NITROGEN FERTILISERS AND WATER-RETAINING POLYMER ROOT DIPS ON SURVIVAL AND GROWTH OF NEWLY TRANSPLANTED BARE-ROOTED SILVER BIRCH (BETULA PENDULA ROTH.) AND EUROPEAN BEECH (FAGUS SYLVATICA L.)

Abstract

Summary The influence of carbohydrates and slow release nitrogen fertilisers in combination with a water-retaining polymer applied as a dip to the root system of two transplant-sensitive tree species, silver birch (Betula pendula Roth.) and European beech (Fagus sylvatica L.) under field conditions was investigated. The efficacy of the treatment on growth was quantified by recording root and shoot growth and survival at weeks 8 and 24 after bud break. Improvements in tree vitality were assessed by measurement of leaf photosynthetic rates, chlorophyll fluorescence and chlorophyll content. Irrespective of species applications of a water-retaining polymer alone had no significant effect on tree survival rates or tree vitality. Results show that carbohydrates and nitrogen fertilisers singly and in mixtures when combined with a water-retaining polymer applied as a root dip at the time of planting can be used to reduce transplant losses and improve tree vitality and growth over a growing season in two difficult-to-transplant species. Although the magnitude of the response differed between species, in all cases where carbohydrates and nitrogen fertilisers were applied a decrease in the shootiroot ratio was recorded at week 8 and 24 post treatment indicating resource allocation in favour of root over leaf and shoot growth.