An Experimental Study of the Rest 

 Period in Plants 



Seeds 

 FOURTH REPORT 



W. L. HOWARD 



Plant physiologists have known for many years that certain 

 seeds appear to pass thru a resting phase before they will germinate. 

 It is also a matter of common experience that seeds of most economic 

 plants appear to be improved by being stored for a few weeks before 

 planting. Gardeners are familiar with the fact that a few kinds of 

 vegetable seed will sprout quickly when planted immediately after 

 ripening, and that some will germinate readily even before they 

 are mature. 



Germination in seeds may be delayed thru a number of causes. 

 Chief among these is the rest period. Old seeds often germinate slow- 

 ly, if at all. Some seeds quickly lose their ability to sprout, or germ- 

 inate slowly and make a weak growth, on account of injury in storage. 

 Common field corn is a good example. As a rule if seeds are harvested 

 when immature, they germinate badly. Wet weather at harvest time 

 is apt to cause seeds to possess low vitality. Seeds may easily be 

 injured where it is necessary to cure them artificially before storing. 

 Such injury is the result of too severe drying out. Great extremes 

 of heat and cold during storage lowers the vitality of many seeds. 

 Too much moisture in the air during storage is fatal to most field and 

 garden seeds. On the other hand, fleshy seeds, like acorns, may die in- 

 a uniformly dry atmosphere. 



Seeds may fail to germinate if planted too deeply or if the soil' 

 be cold or too wet. Exclusion of air (oxygen) will generally pre- 

 vent germination. No seed can germinate where there is an in- 

 sufficient supply of moisture. 



The nature of the seed coat often determines whether a seed 

 will germinate quickly or slowly, or even at all. The seed coat may 

 be naturally hard and almost impervious to water, or it may become 

 so from drying out in storage. Such seeds must be planted at once 

 following maturity, or kept where they are in contact with a moist 



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