Container nursery methods for producing seedlings of chinese pine (Pinus tabulaeformis Carr.) and oriental arborvitae (Thuja orientalis (L.) Franco)

An experiment was conducted to determine the suitability of nine types of plastic or paper containers for raising planting stock of Chinese pine (Pinus tabul aeformis Carr.) and oriental arborvitae (Thuja orientalis (L.) Franco). Plants were grown on the campus of the University of British Columbia, initially, in an unheated plastic shelter and later in a shade house. Height, root-collar diameter and dry weight measurements were taken 22 weeks after germination. Results showed that dry matter production per unit area increased as container spacing decreased. However, the dry weight of individual plants increased with increase in both the volume and spacing of containers. Shoot/root and height/root-collar diameter ratios decreased with increase in container spacing. A controlled experiment, in which plant density was varied independently of container volume, showed that with closer seedling density shoot height increased, but root-collar diameter decreased. In P. tabul aeformi s but not T. orientalis, there was a significant negative relationship between seedling density and whole plant dry weight. A controlled experiment in which container volume was varied independently of plant spacing showed a significant positive relationship between container volume and total plant dry weight in both species. Comparison of three mineral nutrient regimes indicated that elevation of phosphorus level at the beginning and end of the growing season did not increase seedling dry matter production. Growth was better when nitrogen was supplied at 100 ppm, than at 250 ppm. Lateral roots of both species were prevented from growing down or around the container wall by painting the inside of the containers with acrylic latex paint containing cupric carbonate. The chemically-inhibited roots were able to resume elongating after the seedlings were transplanted from the containers. Thus, after transplanting, the primary lateral roots of the chemically root-pruned plants extended straight out from the tap root. In contrast, the primary roots of plants from unpainted containers grew mainly from the lower end of the root plug where they were air-pruned after growing down the container wall. In trials with kraft paper containers, the paper disintegrated before the end of the growing season. Thus roots of adjacent seedlings became intermeshed and were difficult to separate. This was prevented either by using polyethylene coated kraft paper, pr by impregnating the paper with copper sulfide. Lateral roots of seedlings raised in copper sulfide impregnated paper containers were pruned as efficiently as those of seedlings grown in copper-painted plasic containers, yet retained the capacity to resume elongation after transplanting.Forestry, Faculty ofGraduat