Effect of chemical root pruning on stem growth, root morphology and field performance of the Mediterranean pine Pinus halepensis Mill.

The objective of this study was to determine the influence of chemical root pruning on the nursery growth of (1 + 0) Pinus halepensis seedlings and assess their outplanting performance. The experiment was conducted in an open-air nursery and the seedlings were grown in Quick-pots coated with 0, 0.0083 and 0.033 kg/l CuCO3·Cu(OH)2. At the end of the nursery growth period, seedling above-ground and below-ground morphological characteristics and nutritional status were assessed. Following, the seedlings were planted in the field and survival and growth were recorded for two growing seasons after planting. The most significant effect of chemical root pruning was on seedling morphology. Increased copper concentration on the container walls led to seedlings with significantly greater height, diameter, shoot and root biomass and quality index. However, there were no differences among treatments for field survival which was high, in all treatments, 2 years after planting. Seedlings field height was not affected by copper treatment, in contrast to the diameter and stem volume which were significantly greater in the seedlings subjected to higher copper concentration treatment.