





THE CHEMISTRY OF AGRICULTURE 



PART I 



THE PLANT 



CHAPTER I 



GERMINATION OF THE SEED 



The seed of a plant contains besides the growing part or 

 embryo, food material to nourish the seedling until it can pro- 

 duce enough roots and leaves to be independent. The food 

 is stored away in a very concentrated form either in seed 

 leaves called cotyledons, which are part of the embryo, or 

 in a special depository called the endosperm which is merely 

 connected with the embryo. Peas and beans are good ex- 

 amples of seeds with food in cotyledons; corn and wheat, of 

 those with food in endosperms. The food material in the 

 cotyledons or in the endosperm consists of starch, oil, and 

 protein, the relative amounts of which vary with the kind 

 of seed. Fig. 5 shows the interior of a corn kernel and the 

 distribution of these foods. 



1. Conditions for Germination. — In germinating, a seed first 

 sends out a primary root which starts down into the soil, 

 then it puts forth toward the light a seed bud or plumule, 

 with or without its attendant cotvledons as the case may be. 

 Only under certain conditions, however, will a seed germinate, 

 and these conditions are: Presence of a certain amount of 

 icater; oxygen; and heat. All three of the conditions must be 

 2 



