Storability measures of Norway spruce and Scots pine seedlings and assessment of post-storage vitality by measuring shoot electrolyte leakage

Abstract

As indoor frozen storage is increasing in forest tree nurseries it is important to have accurate methods for assessing seedling storability in autumn and methods to determine post-storage vitality. Storability of spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) seedlings can be based on determination of dry matter content (DMC) of seedling shoots or by freezing shoots at –25°C and thereafter measure electrolyte leakage (SEL_diff–25). To compare these two methods we stored 1-year-old spruce and pine seedlings at different occasions during the autumn. To test if leakage of electrolytes from shoots (SEL) could indicate deteriorated vitality, we measured SEL at the end of storage. After storage seedling viability was determined in a three-week growth test, measuring shoot and root growth capacity (RGC). Determination of freezing tolerance (SEL_diff–25) before storage had a better ability to predict the outcome of storage compared to the DMC test. Measuring SEL at the end of the frozen storage period accurately indicated seedling vitality. Seedlings with SEL of 0–5% had a high survival rate whereas SEL over 10% indicated low survival and growth capacity after storage. The SEL method has a potential to become a screening test for identifying batches of seedlings that have been damaged during storage in the nursery.

Keywords:

• seedling status
• containerized seedlings
• hardening
• dehardening
• freezing test
• dry matter content

Acknowledgements

We wish to thank Marianne Vemhäll for all her help with laboratory work. Also, we want to thank Anders Lindgren at Bergvik Skog AB, Nässja nursery for providing experimental seedlings and for good cooperation while we carried out the experiments. Thanks for helpful comments from anonymous reviewers.

Funding

This study was supported by the Royal Swedish Academy of Agriculture and Forestry (KSLA, SLO-foundation), The Knowledge Foundation, Dalarna University and the Swedish University of Agricultural Sciences.

Additional information

Funding

Funding: This study was supported by the Royal Swedish Academy of Agriculture and Forestry (KSLA, SLO-foundation), The Knowledge Foundation, Dalarna University and the Swedish University of Agricultural Sciences.