The effect of root pruning on the root system of nursery trees

摘要: Pruning root systems of landscape-size Colorado blue spruce [Picea pungens Engelm.) in the nursery, 5 years before transplanting, increased number roots and amount surface area ball. The total harvest-ready 2m tall trees was from 122,000 cm to 245,000 cm. ball root-pruned contained approximately four times as much that were not rootpruned. Root balls 11.8 percent whole system compared 5.8 unpruned systems. Sixty pruned inside dripline 40 absorbing transplanted with should help increase survival reduce transplanting shock. pruning nursery shade has been widely practiced recent years. This is because there perception cost effective improving growth after transplanting. It calculated less than moved a typical tree (11). Proper balance between crown necessary for optimum (2, 13). Minimizing imbalance imposed by speed restoration rootcrown ratio, resulting vigorous growth. Since potential confine relatively small volume, tremendous promise using it rootlets tree. More result vigor trees. This, turn, could make economically attractive. When severed, most subsequently regenerated originate callus tissue formed very near cut end 12). Therefore, several inches interior eventual perimeter would insure inclusion these final Most previous studies on have concerned performance seedlings following rootpruning quality seedling In short term, generally induces water stress reduced (4, 9). Long term either unaffected (3, 4, 7, 9) or (1, 5, 8). pruning, combined careful planting, results distortion 6). Little work done stock prepare landscape. Methods (Picea pungens) obtained two commercial nurseries Portland, Oregon studied. Plants both sources (6ft) at time harvesting 1985. Trees one source within 1m (3ft) plants 30cm (12in) prune plants. took place while dormant, prior 1981 growing season. temporarily slows growth, obtain equal size, 8-year-old 10-year-old used. distributions determined collecting consecutive series soil samples radial direction starting base trunk. A U-shaped pit dug expose rectangular slab 150cm (60in) long x 15cm (6in) wide 46cm (18in) deep. divided into rows (shallow deep) 10cm (4in) 23cm (9in), each placed separate plastic bag transported laboratory. Each sample soaked overnight then washed free soil. Fine (less mm diameter) separated larger debris hand stored measurement. Three three ' Supported part Denison Gold Label Nurseries, Wilsonville, OR ^Professor, Department Horticulture, Ohio State University, Columbus, Journal Arboriculture 13 (5): May 1 987 2 7 sampled side isolated other harvested 71cm (28in) diameter deep comparisons within. greater those usually accepted normal size industry. These field fine collected all severed 5mm measured Surface used primary measurement system. Decagon Devices, Inc. Delta-T Area Meter. Results horizontal distribution indicated had dense concentration center, declining sharply outside (1 2in) radius, continuing decline slower rate out fivefoot limit sampling (Fig. 1). Although actual density (measured area/cc soil) decreased increasing distance trunk treatments, volume available exploration square Horizontal values thus converted estimate 2). For tree, under curve shows 60 beyond dripline. altered this somewhat, but still more Photographs reassembled their original orientation 3) reinforce data. Size entire data (Table average (38,000 in) area. only (19,000 overall two-fold uniform throughout distribution. Within 407% (386% dry wt.); 180%. measurements are agreement estimated values, show four-fold Dry weight confirmed (table 1) oi 20 c o> ~-E d g e r o t b