SOIL TEMPERATURE FOR PLANT GROWTH 449 



Table LXVI 



Melons 



Tobacco 



Maize 



Red clover and alfalfa 



Barley and vetch 



Turnips 



Oats 



Flax 



Rye 



Mustard 



Temperatures for germination in degrees 

 Fahrenheit 



Minimum Optimum 



55-65 

 50-60 

 45-50 

 40-45 

 38-45 

 36-45 

 32-45 

 32-40 

 32-40 

 32-38 



88-100 

 75- 90 

 75- 85 

 75- 95 

 60- 75 

 85- 90 

 70- 85 

 75- 80 

 60- 75 

 60- 85 



Maximum 



110-120 



90-110 



90-100 



100-110 



100-105 



100 110 



90-100 



85- 95 



90-100 



90-100 



These figures show that germination may take place 

 as low as 32 Fahr. for some seeds, but that the best 

 temperature is from 60 to 90 Fahr., with the average 

 near 85. Few seeds germinate at temperatures much 

 above 100 Fahr. At temperatures below the optimum, 

 the time required is correspondingly increased, as 

 shown, for example, by Nobbe, who found that musk- 

 melon seeds required 290 hours to germinate at 60.5 

 Fahr., but at 88 Fahr. they germinated in forty-eight 

 hours. The long period may give opportunity for 

 certain fungous diseases to destroy the seed. 



317. Growth and vegetation. Growth seldom takes 

 place below a temperature of from 40 to 50 Fahr., and 

 a much higher temperature is necessary for vigorous 

 growth. Hall presents the following table, showing the 

 relation of temperatures to the growth of some common 

 crops. 



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