Germination of Forest Trees 1 5 



The Germination Process (io, 11, 12, 13) 



This period in the life history of the green plant is unique in 

 that the organism is independent of an external food supply and 

 also of all luminous energy. Germination may be called a period 

 of growth without photosynthetic activity, and it terminates at the 

 time the accumulated food in the endosperm is more or less ex- 

 hausted. During all this time it is without light; it does not 

 require it, but lives in total darkness beneath the surface of the 

 soil. While the seed has no use for light, it does require water, 

 oxygen, and a certain amount of heat in order to germinate suc- 

 cessfully. The dependent life of the plant begins at the termina- 

 tion of the process of germination, when the first ray of light 

 strikes the spreading cotyledons. Light sets the photosynthetic 

 mechanism in motion and this marks the beginning of the plant's 

 manufacture of food ; henceforth it is dependent upon its en- 

 vironment. - 



The role of water in the germination process is to aid in the 

 transformation of the accumulated nutrient material into food 

 that can be used by the germinating embryo. In other words, 

 this factor is instrumental in taking this sunken capital and trans- 1 

 forming it into specie for circulation. But water cannot do this 

 directly; it must act through the agency of certain catylists or__ 

 enzymes. These enzymes transform insoluble and indiffusible 

 foods into soluble and diffusible ones which in turn move from 

 the endosperm to nourish the embryo. 



Water is important to the seed for two reasons; its absence] 

 determines the seed's power to live in a dormant condition, which/ 

 is one of its most important properties. If a seed is not dry ii 

 cannot be preserved ; we cannot secure good seed in a wet autumn. £_ 

 The second reason why water is important is because of its 

 chemical and mechanical action in germination. Hales at the/ 

 beginning of the eighteenth century showed that the absorption or 

 water by seeds is generally accompanied by a considerable mani- 

 festation of energy, which takes the form of swelling. Chemically 

 water acts as a solvent for the enzymes which render the ac- 

 cumulated foods soluble. 



