FOREST TREE SEED AND SEED COLLECTING 



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commercial tree seed. Viability was determined by germination 

 tests and equals the average percentage of germination at the 

 end of the tests plus the average number of sound seed. The tests 

 were made in soil and varied from 30 to 100 days depending upon 

 the species. All tests were continued 100 days when there were 

 sound seed that had not germinated. The above table should not 

 be followed blindly in using commercial seed. With more care 

 in collecting and storage the average viability is constantly 

 increasing. 



The deviation from average viability is shown in the tests on 923 

 samples of seed at the Prussian testing -station from 1907 to 1909 

 inclusive reported by Schwappach. The following table from his 

 report shows the average maximum and minimum viability, the 

 difference being largely due to the effect of good and poor seed 

 years upon viability. The seed was tested in germinating dishes 

 of porous clay and on bibulous paper in a lighted room kept at 

 a temperature of 77 F. 



More recently Rafn * has published a comprehensive report on 

 the germination of the seed of many of the forest trees of the 

 United States, the investigations covering the years from 1887 to 

 1912. The following table compiled from his report shows the 

 highest and lowest germination values met with in the tests made. 

 The numbers within the parentheses preceded by the plus sign 

 represent the ungerminated seeds that were sound at the end of 

 the test. The tests were made mostly on bibulous paper in the 

 Jacobsen germinator. 



1 Rafn, Johannes: The testing of forest seeds during 25 years. (Printed by 

 the author for private circulation.) 1915. 



