Effects of container volume and shape on the growth of black spruce (Picea mariana (Mill.) B.S.P.) seedlings

Abstract

The objective of this thesis was to evaluate the growth of black spruce seedlings in containers with four soil volumes (45, 90, 180, 360 cm3) and at three diameter/depth shapes (1:2, 1:3, 1:4). Seedling height, root collar diameter, top dry weight and root dry weight were measured after 16 weeks in the greenhouse and after one growing season in the -field. Analyses of variance (ANOVA) and multiple linear regressions (MLR) were completed for each of the morphological characteristics and for the corresponding seedling quality indices. The ANOVAs and MLRs were used to evaluate seedling growth and quality in order to determine the optimum container volume and shape necessary for the production of high quality black spruce stock. The growth and quality of black spruce stock significantly increased with increasing container volume and with change in container shape from deep and narrow (1:4 diameter/depth ratio) to shallow and wide (1:2 diameter/depth ratio). These changes were detected in the greenhouse production phase and became very evident after outplanting in the field. To produce high quality black spruce seedlings for outplanting, the container volume should exceed 80 cm3 and the container shape should have a 1:2 diameter/depth ratio. Black spruce grown in 1:2 diameter/depth shaped containers that range from 30 to 180 cm3 in volume will be of high quality and have a total dry weight between 1.0 and 1.4 g after 16 weeks in a greenhouse. Black spruce grown in 1:2 diameter/depth shaped containers that range from 180 to 360 cm3 in volume will be of superior quality and have a total dry weight between 1.4 and 1.7 g after 16 weeks in a greenhouse.