Optimum Temperature 



The temperature of 23 °C used for macrophyte culture on 

 this project was established from the data presented 

 in Figure 5. The growth of Elodea, as length increase 



*- Constant 23°C 



—Control 

 —Variable 



23° 20 - 26° ' 29° 32' 



Variable temperature (°C) 



Figure 5. The growth of Elodea occidentalis m as length in- 

 crease, during exposure to various temperatures. 



was compared in a set of trays maintained at 23 °C and 

 in trays exposed to temperatures varying from 20 to 

 32°C during different phases of the culture period. 



Growth was slightly less at 20°C than at 23°. There were 

 were only slight differences in growth at 23°C and 

 temperatures up to 32°C. It seems, therefore, that Elodea 

 is not highly sensitive to temperatures within the 20 to 

 30°C range. 



49 



