Methods in Germination Tests of Coniferous Tree Seeds 77 



seeds could endure a temperature of 35 degrees C. (95 v degrees 

 F.) for a short time without injury. Hiltner and Kmzel* 



*Hiltner and Kinzel: uber die Ursachen und die Beseitigung der Kei- 

 mungsliemmungen. Xaturwissenschai'tliehe Zsitschrift fur Liand und 

 [< orstwirtschaf t, 4:44. 



materially increased the germination per cent of white pine 

 seed within a forty-two day period by applying a daily tempera- 

 ture of 30 degrees C. (86 degrees F.) for six hours and then 

 20 degrees C. (68 degrees F.) for the remaining eighteen hours of 

 the twenty- four hour period. Bates** used a temperature range 



**Bates: Technique of Seed Testing. Proceedings of the Society of 

 American Foresters, 8:131. 



of 30 degrees F. per twenty-four-hour period with the ex- 

 tremes at 55 degrees F. and 85 degrees F. Kinzel***, working 



***Kinzel. W.: uber die Wirkung wechselnder Warmheit auf die Keimung 

 einzelner Samen. (Landw. Vers. Stat., 54:134-139). Abstract in Experi- 

 ment Station Record. 12:5ff3. 



with Scotch pine ( Finns silvestris), Norway spruce (Picea 

 c.vcclsa), and larch (Lari.r sp.), found that in the case of the 

 Scotch pine seeds those which had been exposed to a temperature 

 of 30 degrees C. for six hours and then 20 degrees C. for the 

 remaining eighteen hours of the twenty-four-hour period gave a 

 lower germination than those exposed to a uniform temperature 

 of 20 degrees C. (68 degrees F.). In the case of Norway 

 spruce and larch, however, higher practical germination per cent 

 was secured by exposure to varying temperatures ; the larch 

 also yielded a slightly higher final germination per cent. The 

 writer used a daily range of 25 degrees F. with a minimum of 

 55 degrees and a maximum of 80 degrees in the greenhouse with 

 satisfactory results. 



The question of the influence of descent, that is of the 

 mother tree, and of the source (locality from which the seed is 

 obtained ) on the germination of seed is too broad a question to 

 permit of treatment in this paper. Circular 196 of the United 

 Braces Forest Service by G. A. Pearson entitled, "The Influence 

 of \ge and Condition of the Tree upon Seed Production in 

 Western Yellow Pine", gives some interesting results along this 

 line. 



Age of the seed, of course, has a direct influence on germina- 

 tion, the final germination decreasing with the increase in age. 

 But even if the decrease in the final germination is not distinctl) 

 apparent during the first two or three years for seed properly 

 stored, the decrease in the practical germination is usually 



