Seed germinofion 



10 



A mature seed contains an embryo and stored food enclosed in one 

 or two seed coats. One seed coat is invariably hard and woody. When 

 a seed has two coats, the inner one is little more than an extremely 

 thin membrane. The embryo is the potential plant and develops from 

 the fertilized egg, while the seed is a part of the parent. The growth 

 of this embryo is arrested in most mature seeds, and the embryo 

 remains in a state of rest as long as the seed is stored in a cool, dry 

 place. The resumption of growth of the embryo after this dormant 

 period and the emergence of the young plant arc called germination. 



Since the embryo cannot synthesize its own food, it must depend 

 on stored reserve materials for its nourishment. When a seed is placed 

 in the proper environment, the embryo resumes its growth by utilizing 

 the stored food and eventually becomes a more highly developed 

 structure with some of the characteristics of the parent plant. At 

 this stage of its growth the young plant is called a seedling. 



CHEMICAL COMPOSITION OF SEEDS 



Seeds contain variable quantities of the elements and compounds 

 that are necessary for the formation of the new tissues characteristic 

 of the seedling. Organic compounds such as lipides, proteins, and 

 carbohydrates predominate. Various substances, in addition to those 

 found in the three large classes of compounds just mentioned, are 

 also present. Both macro- and micronutrient elements are present in 

 sufficient amounts to assure the growth of the young seedling to the 



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