Effect of preplanting drought on survival, growth and xylem water potential of actively growing Picea abies container seedlings

Abstract

The effect of preplanting drying of root plugs on survival, height growth and root egress of actively growing 12-month-old Norway spruce [Picea abies (L.) Karst.] seedlings was examined in dry and wet soil between 5 July and 17 August 2000. In addition, the response of seedling xylem water potential and survival to the decreasing water content of the root plug (v/v) was examined in the greenhouse. Most seedlings were dead when the water content of the root plug decreased to <7% and xylem water potential to <−2.8 MPa. The higher the water content of the root plug at planting, the greater the height growth in both dry and wet soil. However, root growth was promoted by the increase in the water content of the root plug only up to approximately 30%. In wet soil height growth was greater but root growth poorer than in dry soil. All measured variables were strongly affected when the water content of the root plug decreased to <20% at the time of planting.

Keywords:

• Height growth
• Norway spruce
• root egress
• root plug
• summer planting
• water stress

Acknowledgments

This study was financially supported by a grant from Metsämiesten Säätiö Foundation to Pekka Helenius. The authors thank Ritva Pitkänen and Liisa Huttunen MSc for technical assistance, and Dr Juha Lappi for statistical assistance. Dr Robin Rose and one anonymous referee made valuable comments on the manuscript.