The First Four Years' Growth of Containerized Japanese Cypress (Chamaecyparis obtusa) Seedlings and the Possibility of Reducing the Number of Weedings

Abstract

We compared the growth of containerized and bare-root Japanese cypress (Chamaecyparis obtusa) seedlings for four years after planting, and also investigated the competition between seedlings and their surrounding weeds to assess the possibility of reducing the number of weedings. The height and diameter growth of the containerized seedlings was equal to or higher than those of the bare-root seedlings, though the superiority of the formers' relative growth rate was not evident after the first year. With regular weeding, once a year over the four years, the weeds observable in the summer of the fifth year were Miscanthus sinensis and deciduous shrubs (roughly 150 cm in height). The average height of the containerized seedlings at this time was 284 cm, roughly 40 cm higher than that of the bare-root seedlings. We considered that this was owing to the fact that the containerized seedlings had been reared with slow-release fertilizer, eluted over longer periods than usual, as base fertilizer. Furthermore, the vertical competition between the seedlings and weeds abated one year earlier than in the case of the bare-root seedlings, and weeding could be omitted, in the summer of the fifth year, in the containerized seedling plot. Consequently, it was suggested that the number of weedings could be reduced by one year in the case of the containerized seedlings.