120 SEEDING AND PLANTING 



As fast as the seeds germinate, they are removed and a record 

 kept of the number that germinate each day during the test 

 (Fig. 23). 



30. Germination Temperatures. A fluctuating temperature 

 within certain limits is more favorable to germination than a con- 

 stant temperature. Under natural conditions the temperature 

 during the day is considerably higher than at night. This daily 

 change in temperature stimulates the germination of seed, as 

 demonstrated by many researches in recent years. In hothouse 

 tests a fluctuating temperature corresponding to natural conditions 

 should be maintained. At the Fremont forest experiment station 1 

 the seed is subjected to a daily fluctuation in temperature of ap- 

 proximately 30 F., falling at night to 55 F. and rising in the day to 

 85 F. Schwappach, 2 in a report from the Prussian seed-testing 

 station at Eberswalde, states that the tests are made in a lighted 

 room kept at a constant temperature of 77 F. He states, how- 

 ever, that white pine seed germinates more quickly by exposing it 

 first to a temperature of from 41 to 50 F. and later raising it to 

 77 F. Zederbauer, 3 in most of his tests, subjected the seed to a 

 fluctuating temperature, lowered to 59 F. at night and raised to 

 73 F. during the day. When the seed was subjected to a con- 

 stant temperature it was maintained at 73 F. Seed from hot 

 climates requires a higher temperature for germination than seed 

 from cold regions. Seed that naturally germinates in early spring 

 requires a cooler temperature than seed from the same locality 

 that germinates later when the weather is warmer. Old seed 

 usually germinates better under a moderately low temperature. 

 The marked effect of temperature upon the rapidity, uniformity, 

 and capacity for germination and the lack of uniformity which 

 now exists in germination tests make the standardization of tem- 

 perature conditions for seed tests extremely important. 



31. Special Treatment to Hasten Germination 



Various methods of seed treatment have been advocated for the 

 purpose of hastening germination. In general, the germination 



1 Bates, C. G.: The technique of seed testing. (Proc. Soc. Am. For., vol. 

 VIII, pp. 127-138. 1913.) 



2 Schwappach, Adam: Mitteilungen aus der Waldsamen. (Zeitschrift 

 f. Forst- u. Jagdwesen, S. 753-762. 1909.) 



3 Zederbauer, E.: Die Keimpriifungsdauer einiger Koniferen. (Central- 

 blatt f. d. gesamte Forstwesen, S. 306-313. 1906.) 



