Pruning northern red oak nursery seedlings:effects on root regeneration and early growth

Northern red oak seedlings were top-pruned in the seedbed each month from August until the next March. In late March, all trees were lifted, planted in the greenhouse, and harvested 30 days later. Any top-pruning treatment that directly or indirectly removed the leaves in late summer or early fall markedly reduced root regeneration and initial shoot growth after planting in March. Removal of all the visible buds at any date resulted in increased numbers of new shoots after planting, while pruning stems at the groundline reduced new shoot growth.In additional studies, shoots and roots of trees lifted in March were pruned to various levels before planting. Results indicated that root pruning influenced seedling growth much more than shoot pruning. The amount of new shoot growth was significantly correlated with root weight of seedlings when planted, whether differences in root weight were natural or obtained by pruning. The effects of shoot pruning and root pruning on seedling growth were largely independent of each other.