Effects of copper root pruning and radicle pruning on first-season field growth and nutrient status of Chinese cork oak seedlings

Abstract

© 2016, Springer Science+Business Media Dordrecht. Root deformation is a common challenge in container seedlings especially for vigorous-rooted tree species. The issue is significant for Chinese cork oak (Quercus variabilis Blume.) which is grown in cost-effective polybags. In this study we examined how copper root pruning and radicle pruning (1/3 or 2/3 of radicle length) individually and together (1/3 radicle pruning in combination with copper root pruning) affected root architecture, growth and nutrient storage of nursery seedlings, and survival, growth performance and nutrient status during the first outplanting season. Copper root pruning failed to reduce root spiraling, and decreased total root length and surface area by decreasing root length and surface area of roots with diameter <5 mm. In contrast, radicle pruning decreased root deformation and induced taproot formation. However, intensity of radicle pruning impacted seedling size at planting and 2/3 radicle pruning decreased height and stem dry mass relative to the control. Root effects of combination (radicle plus copper root pruning) treatment on root development were not superior to 1/3 radicle pruning. Combination treatment decreased roots with diameter <2 mm. Overall 1/3 radicle pruning has the best potential to modify root development for vigorous-rooted Chinese cork oak seedlings grown in polybags.