70 



SEEDS AND FRUITS 



The vitality and vigor of seeds depend upon the following 

 factors: (1) the vigor of the plant which produced the seeds; (2) 

 external conditions which affect seeds during their development; 

 (3) maturity of seeds; (4) weight and size of seeds ; (5) methods 

 of storing; and (6) age of seeds. 



The seeds of vigorous plants are preferable to those of weak 

 plants, for the sperms and eggs of vigorous plants are likely to be 

 more vigorous than those of weak plants, and, therefore, more 

 capable of producing vigorous embryos. Furthermore, seeds 

 of vigorous plants may have more stored food for the embryo to 

 feed upon during germination and the seedling stage. Plants 

 having a stunted growth, due to drought, lack of food, or attacks 

 of enemies, are likely to produce small and often shriveled seeds 

 which are lacking in stored food and usually have weak embryos. 



Seeds are often injured by frosts occurring while the seeds are 

 immature and full of water. The embryos of Corn and other 

 seeds are sometimes killed by early frosts. Even seeds which 

 have reached maturity cannot endure hard freezing unless they 

 are dry. For this reason most seeds should be collected from 

 the field before they have been exposed to a hard freeze. 



Abnormal seeds have a low vitality or will not germinate at all. 

 Kernels of Corn produced on the tassel usually give a low per- 

 centage of germination. Sometimes, as in case of Sweet Clover 

 and Alfalfa, when the conditions are unfavorable, seeds are pro- 

 duced with imperfect embryos which are not capable of developing 

 plants. There are some plants in which seeds sometimes develop 

 without embryos and of course will not germinate at all. This 

 sometimes occurs in the Apple and Pear. When seeds are muti- 

 lated their vitality is usually impaired. Larbaletrier asserts that 

 15 per cent of the Wheat crop in France is injured by the thresh- 

 ing machine. He cut the kernels with a knife so as to represent 

 the injury from the machine and compared their germinative 

 power with that of sound kernels, obtaining a much lower per- 

 centage of germination as the results given in the table below 



