Chapter 9 

 GERMINATION OF SPORES 



The process of germination of spores is generally regarded as 

 belonging among growth phenomena and hence being subject to 

 modification by all those factors that influence growth. Spore 

 germination has much in common with seed germination, as might 

 be anticipated, and much of value has been learned by mycologists 

 from the techniques and interpretations of those who have studied 

 the termination of seeds. Manifestly the factors that affect the 

 orermination of spores, just as that of seeds, are of two types: 

 hereditary or internal, and environmental or external. Hereditary 

 factors include the maturity", longevity, dormancy, and vitality 

 of spores. The environmental factors include the influence of 

 moisture, temperature, pH, kind and concentration of nutrients, 

 light, and the presence of oxygen and carbon dioxide. 



Both saprophytic and parasitic fungi have been used in spore- 

 germination studies, more especially the parasitic, because weather 

 conditions are known to influence the incidence and relative 

 prevalence of plant-disease outbreaks. In attempts to evaluate the 

 relative importance of environmental factors to plant diseases, 

 the pathogens have been grown in culture, and, as an incidental 

 result, our knowledge of spore germination has been increased. 



GERMINATION TYPES 



Different kinds of spores germinate differently. Sometimes 

 the type of germination is characteristic of a large number of 

 closely related species. In other cases environmental factors exert 

 a controlling influence on the type of germination within the 

 same species. Among the aquatic Phycomycctes each propaga- 

 tive element is at first a mother cell whose content breaks up 

 into intracellular units of protoplasm, which, after escape from 



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