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at room temperatures, in cool cellars, 

 or frequently in special seed-storage 

 sheds. Seeds of many species can be 

 kept for one or more years in such 

 sheds, but for longer periods cold stor- 

 age is necessary. 



Seeds of many woody plants keep 

 well at temperatures between 33 and 

 50 F. Before storage, seeds of most 

 conifers should be dried to a moisture 

 content below 10 percent of oven-dry 

 weight. Seeds of the oaks, hickories, 

 and silver maple, however, should be 

 kept above 35-percent moisture con- 

 tent, and those of southern magnolia 

 should not be allowed to dry at all. 

 Proper cold storage requires a refrig- 

 erator or cold room in which tempera- 

 tures can be held nearly constant. 

 Sealed containers maintain the right 

 moisture content and are best for such 

 storage. 



Many of the nuts and some other 

 seeds often can be stored for a few 

 months by mixing them with one to 

 three times their volume of moist peat 

 moss, sand, or chopped sphagnum 

 moss, and placing them in a refrigera- 

 tor or holding them over winter in the 

 ground under a mulch. Sometimes 

 fall sowing is used instead. 



The short-lived seeds of the poplars 

 can be kept fairly well for several 

 months in sealed containers from 

 which much of the air has been ex- 

 hausted by suction pumps, or in which 

 the relative humidity of the air is less 

 than 20 percent. So far, however, 

 vacuum storage has been attempted on 

 a laboratory scale only. 



Under proper storage, seeds of most 

 trees can be kept viable for 5 to 10 years 

 and that of some species has been kept 

 for several decades. The best storage 

 methods known for several species 

 follow : 



Dry, cold storage in sealed con- 

 tainers: Apples, arborvitaes, ashes, 

 barberries, bigcone-spruce, birches, an- 

 telope bitterbrush, blackberries, silver 

 buffaloberry, ceanothuses, lilac chaste- 

 tree, the cypresses, Douglas-fir, elders, 

 elms, firs, riverbank grape, hackber- 

 ries, hemlocks, honeylocusts, common 



Yearbook of Agriculture 1949 



hoptree, black huckleberry, junipers, 

 larches, black locust, maples (other 

 than silver) , the mountain-ashes, oleas- 

 ters, Osage-orange, pines, some pop- 

 lars, common prickly-ash, raspberries, 

 eastern redbud, redwood, sassafras, 

 giant sequoia, the snowberries, spruces, 

 sumacs, sweetgum, witch-hazel, yellow- 

 poplar. 



Moist, cold storage: Beeches, buck- 

 eyes, chestnut, chinquapins, filberts, 

 hickories, silver maple, oaks, tanoak, 

 walnuts, yews. 



At air temperatures: Acacias, Ken- 

 tucky coflfeetree, eucalyptus, fremon- 

 tias, common lilac, lindens, common 

 pear, the Siberian pea-shrub, European 

 privet, meadow rose, fourwing salt- 

 bush, the common sea-buckthorn, com- 

 mon winterfat. 



Under partial vacuum: Some pop- 

 lars. 



PRETREATMENT is SOMETIMES re- 

 quired. Seeds of some trees and shrubs 

 germinate quite promptly. Those of 

 many, however, often fail to sprout 

 even when exposed to suitable condi- 

 tions of temperature, moisture, oxygen, 

 and light. Such seeds are called dor- 

 mant, and special treatment is required 

 to induce germination. 



There are two main causes of seed 

 dormancy : ( 1 ) An impermeable or 

 hard seed coat which prevents water 

 and oxygen from reaching the embryo, 

 or sometimes prevents the embryo 

 from breaking through even though 

 water has entered; and (2) internal 

 conditions of the embryo or stored food. 

 Many kinds of seeds have only one 

 kind of dormancy, but there are many 

 others which have double dormancy. 



To overcome seed-coat dormancy, 

 seeds usually are subjected to one of 

 the following pretreatments : ( 1 ) Soak- 

 ing in concentrated sulfuric acid (usu- 

 ally from 15 to 60 minutes) ; (2) scari- 

 fying the seed coats with abrasives; or 

 (3) soaking in hot water (usually at a 

 temperature of 170 to 212 F.) for 

 about 12 hours as it gradually cools. 



Treatments used to break internal 

 dormancy are : ( 1 ) Cold stratification, 



