Rikala, R. and Lappi, J. 2010. Prediction of Height Development in First-year Norway Spruce (Picea abies (L.) Karsten) Container Seedlings in a Nursery.   Baltic Forestry 16 (1): 43-49

Most nurseries measure and document records of the environmental conditions and growth variables of seedling crops. The usefulness of this operationally collected data for crop scheduling and predicting seedling height has not been studied. We used operational 10 years’ data (information of growing measures of seedling batches, daily mean temperature and photoperiod, weekly monitored electrical conductivity and water content of growing medium) of commercially grown first-year container Norway spruce (Picea abies (L.) Karsten) seedling batches to predict height development of seedling batches. Our data did not support the idea that the termination of height growth could be predicted accurately on the basis of photoperiod and temperature sum in operational seedling production. The best indicator for the final height was the sowing date. Although the measured variables, especially average weekly nitrogen given, correlated with the final height of seedlings, these variables did not give any additional explanation to sowing date. Within seedling batches the germling height (height of seedling at the age of 5-6 weeks) did not predict well the final height of seedlings.

Key words: fertilization; growth rhythm; sigmoidal function; photoperiod, sowing date; temperature sum