Prolonged cold, moist pretreatment of conifer seeds at controlled moisture content
1996
Poulsen, K.M. (National Forest and Nature Agency, Humlebaek (Denmark). Tree Improvement Station)
Cold pretreatment of imbibed seed (stratification) and seed kept at controlled moisture contents for 3-14 weeks was tested for commercial seedlots of Abies nordmanniana, Abies procera, Pseudotsuga menziesii, and Picea sitchensis in order to give recommendations for nursery practice. The temperature tolerance of treated seed was tested by germinating seed at four temperature regimes, germination capacity and speed of germination were registered. It was possible to pretreat Abies nordmanniana seed at controlled moisture content, but the performance was not improved compared with the traditional six weeks stratification of imbibed seed. For Abies procera seed pretreatment at controlled moisture content for 2 + 8 weeks (2 weeks imbibed followed by 8 weeks at controlled moisture content) or more, significantly improved the performance at the germination temperatures 15 and 30 deg C. For Pseudotsuga menziesii seed pretreatment at controlled moisture content for up to 2 + 12 weeks was superior, especially at low germination temperatures, and it was possible to redry pretreated seed to 8 % moisture content without loss of the pretreatment effect or germination capacity. For Picea sitchensis seeds the controlled moisture content method for a duration of 7-10 weeks proved efficient and pretreated seed of this species also tolerated redrying. These improved pretreatment methods should be introduced into the nurseries
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