18 



PRINCIPLES OF PLANT CULTURE 



mum) temperature at which seeds can germinate varies 

 considerably with different species, and so does the tem- 

 perature at which they germinate quickest (optimum) as 

 also the highest (maximum) temperature at which they 

 can germinate. The following table (compiled from 

 Haberlandt and Sachs) shows approximately the mini- 

 mum, optimum and maximum temperatures at which 

 seeds of the species named germinate : 



These temperatures refer to the soil or other medium 

 with which the seeds are in contact, and not to the at- 

 mosphere. 



When moisture is sufficient, the time from planting to. 

 sprouting decreases rapidly as we approach the optimum 

 temperature. In an experiment, Indian corn sprouted in 

 one-third of the time at 88 F. that it required to sprout 

 at 61. 



