CLIMATE AND PLANT GROWTH. 



55 



Furthermore, the curve representing these percentages bears an 

 intimate agreement with both of the temperature summation curves. 

 This increased conservatism in the use of water in wheat leaves may, 



2002 



\ 



X \ 



\ 



\ 



\ 



\ 



\ 



\ 



Aspen ^Spruce Fir 



Temperature aboise: 4-O* 



Hfafer repu/remerrte per rum. Leaf Lenqfr?( Wheat) 



Ptysto/oqicaj Temperature Efficiency 



Water requirements per mm. Leaf LerHfth[Brome-qrass J 



FIG. 30. Water requirements per unit (1 mm.) of leaf length of brome grass and wheat. 



in a way, account for the high yielding qualities of wheat, other 

 conditions remaining the same, in regions where the summers are 

 relatively cool. 



