168 SEEDING AND PLANTING 



a large series of experiments, has conclusively proved the favorable 

 influence of uniform temperature and the exclusion of air for pine, 

 spruce, and other seeds that permit of storage in dried condition. 

 The exclusion of air maintains the seed in a uniformly dry condi- 

 tion and reduces respiration and transpiration to the lowest degree. 

 For all species that will withstand thorough air-drying without 

 injury it affords the best possible mode of storage. Haack found 

 that the seed of Scotch pine stored in this manner for 2 or 3 years 

 produced from 1.6 to 3.3 times the number of plants obtained 

 from samples of the same lot of seed stored in the open air under 

 the most favorable conditions. 



32. Dry Storage 



Although all species when subjected to temperatures sufficiently 

 cool to reduce respiration and transpiration to a low degree can 

 be stored in a moist atmosphere, seed which will withstand mod- 

 erate desiccation is usually stored dry. 1 



Seed should not be placed in dry storage until it is sufficiently 

 dry to prevent heating and molding. The seed of most conifers 

 can go into permanent storage immediately after cleaning be- 

 cause of the drying that it has undergone during the process of 

 seed extraction. The seed of many broadleaved species, how- 

 ever, is gathered and cleaned some time before it should be stored 

 for the winter. It should be temporarily left in thin layers in a 

 cool, airy place, such as an open shed or barn or on trays on 

 upper shelves in a dry cellar. Excessive drying can be judged 

 from the shrinking of the kernel and can be checked by throw- 

 ing the seed into larger heaps or by partially covering it. It is 

 usually ready for permanent storage in October or November. 



The ordinary methods of dry storage are as follows: 



a. Storage under fluctuating temperature and humidity. 



6. Cold storage. 



c. Storage in sealed cans, carboys, and boxes. 



1 Although the seeds of most conifers are stored dry, if the temperature is 

 sufficiently low they do not suffer when stored over winter in a moist condi- 

 tion. In the autumn of 1906, the author stratified the seeds of 42 species of 

 conifers. They were sown in April the following year. All species had kept in 

 excellent condition and germinated far in advance of the same species when 

 the seeds were stored dry. 



