CHAPTER VI 



GERMINATION OF SEEDS: SEEDLINGS 



Nature of Germination and Factors upon which it Depends 



Although the resting condition is very essential to the preser- 

 vation of the life of the seed during transportation and while 

 awaiting favorable conditions for germina ion, it must be aban- 

 doned at some time in order that the embryo may develop into 

 the plant, the production of which is the seed's chief function. 

 By germination of a seed is meant that awakening from the rest- 

 ing condition in which the young plant shows practically no 

 signs of life to a state of active growth. The term germination 

 is used in different ways, being used to designate the beginning 

 growth of such structures as a pollen tube, fertilized egg, and 

 spore, but in each case, however, it refers to the initial growth. 

 Seeds are considered germinated when the radicle and plumule 

 have broken through and project beyond the seed coverings, 

 although germination is not complete until the little plant is able 

 to live independently of the stored food of the seed. 



Conditions Necessary for Germination. — The awakening of 

 the seed into active growth depends upon the presence of 

 warmth, moisture, and oxygen. Germination is so dependent 

 upon these three external factors that, if either is lacking though 

 the other two are properly supplied, there will be very little or no 

 germination. Among different seeds, the degree of temperature 

 and the amount of moisture and oxygen required for the best 

 germination vary. 



Temperature Requirement. — Seeds vary more in the temper- 

 ature required for germination than in any other factor. Through 

 experience we have learned that among farm and garden seeds 

 there are different temperature requirements for germination, 

 and that the time of season at which different seeds should be 

 planted must be chosen accordingly. Thus Oats, Wheat, and Red 

 Clover seedi^, which have a low temperature requirement, can be 

 planted in the early spring or late fall when the weather and soil are 



