LONGEVITY 



73 



parts of the United States have shown that seeds do not hve as 

 long in the warm moist air of the Southern states as they do in 

 the cool dry air of the Northern states. 



In the following table compiled from various sources is given 

 the time beyond which it is not advisable to use the seeds men- 

 tioned unless the contrary is shown by germinative tests. 



Years. 



2 



2 



Corn 



Wheat 



Oats 2 



Barley 2 



Rye 2 



Buckwheat 2 



Beans (common) 4 to 5 



Peas 4 to 5 



Clovers 2 to 3 



Alfalfa 3 to 4 



Onion 1 



Years. 



Mustard 3 to 4 



Cabbage 3 to 4 



Turnips 3 to 4 



Swede 3 to 4 



Pumpkin 5 



Melon (musk) 5 



Melon (water) 5 



Squash 3 



Tomato 6 



Timothy 1 to 2 



Celery 1 



In some cases perfect seeds well stored may have more than 

 double the longevity given in the above table. Thus Sturtevant 

 obtained 100 per cent germination of various varieties of Corn 

 after being stored 5 years. Tomato seeds 

 14 years old have been known to give a 

 high percentage of germination. On the 

 other hand, using the same seeds as an 

 example, both Corn and Tomato seeds 

 are sometimes unfit for use when only 

 1 year of age. These varying results em- 

 phasize the importance of testing the 

 germinative power of seeds before use. 



The variation in the longevity of the 

 seeds of a given lot is obvious when the 

 percentages of germination for different 

 periods of storage are compared. The 

 decrease in the percentage of germination 

 as the length of the storage period in- 

 creases shows that some seeds die early magnifier from above 

 and others later until finally all are dead. 



In the following table are given the results of an experiment 

 to determine the rate at which vitality is lost as indicated by the 

 percentage of germination obtained in each of the 6 years of 

 storage. 



Fig. 72. — A cheap mag- 

 nifier well adapted for use 

 in analyzing seeds. The 

 magnifier is set over the 

 seeds, leaving the hands 

 free to separate the seeds 

 as one looks through the 



