The impact of mechanical stimulation on the growth of containerized Cryptomeria japonica seedlings during the nursery phase and after planting

Abstract

Mayumi Y. Ogasa, Naoko Yamashita, Ryo Kitagawa, Sakae Fujii, Hiroyuki Tobita: The impact of mechanical stimulation on the growth of containerized Cryptomeria japonica seedlings during the nursery phase and after planting. Ap. For. Sci.

Containerized conifer seedlings often exhibit a high height-to-diameter ratio. To investigate the effect of mechanical stimulation on suppressing height growth, containerized seedlings of Cryptomeria japonica

were subjected to shaking for 3 or 30 min, or stroked 1 or 10 times on their crowns, while monitoring their growth throughout the season. Factors influencing growth rate after planting in the field were also analyzed.

Seedlings stroked 10 times were 15% shorter in height than those in the control (untreated) group at the end of the growing season. The height growth of seedlings shaken for 3 or 30 min was initially suppressed but ultimately comparable to that of the control seedlings by the end of growing season. No significant effects of treatment history on seedling height growth were observed after planting in the field. The height growth

1 year after planting was negatively correlated with canopy openness, while the height growth 2 years after planting was positively correlated with soil electric conductivity and negatively correlated with soil hardness. These results suggest that height growth is constrained by stroking the crown during the container nursery phase, but it was affected more by environmental factors after planting than treatment history.